Internet DRAFT - draft-han-6man-in-band-signaling-for-transport-qos
draft-han-6man-in-band-signaling-for-transport-qos
Network Working Group L. Han, Ed.
Internet-Draft G. Li
Intended status: Informational B. Tu
Expires: April 14, 2018 X. Tan
F. Li
R. Li
Huawei Technologies
J. Tantsura
K. Smith
Vodafone
October 11, 2017
IPv6 in-band signaling for the support of transport with QoS
draft-han-6man-in-band-signaling-for-transport-qos-00
Abstract
This document proposes a method to support the IP transport service
that could guarantee a certain level of service quality in bandwidth
and latency. The new transport service is fine-grained and could
apply to individual or aggregated TCP/UDP flow(s).
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. IP and Transport Technologies . . . . . . . . . . . . . . 4
1.2. TCP Solution Analysis . . . . . . . . . . . . . . . . . . 4
1.2.1. TCP Overview and Evolution . . . . . . . . . . . . . 4
1.2.2. TCP Solution Variants . . . . . . . . . . . . . . . . 5
1.2.3. Throughput Constraint . . . . . . . . . . . . . . . . 6
1.2.3.1. By Algorithm . . . . . . . . . . . . . . . . . . 6
1.2.3.2. By Fairness Principle . . . . . . . . . . . . . . 7
1.2.4. Latency Constraint . . . . . . . . . . . . . . . . . 7
1.2.5. Summary of TCP Solution . . . . . . . . . . . . . . . 7
1.3. Other Solution Analysis . . . . . . . . . . . . . . . . . 8
1.4. New approach . . . . . . . . . . . . . . . . . . . . . . 8
1.4.1. IP Transport with quality of service . . . . . . . . 8
1.4.2. Design targets . . . . . . . . . . . . . . . . . . . 9
1.4.3. Scope and assumption . . . . . . . . . . . . . . . . 9
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 10
3. Control plane . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1. Sub-layer in IP for transport control . . . . . . . . . . 12
3.2. IP In-band signaling . . . . . . . . . . . . . . . . . . 13
3.3. Control mechanism . . . . . . . . . . . . . . . . . . . . 14
3.4. IPv6 Approach . . . . . . . . . . . . . . . . . . . . . . 15
3.4.1. Basic Control Scenarios for TCP . . . . . . . . . . . 16
3.4.2. Details of In-band Signaling for TCP . . . . . . . . 17
3.5. Key Messages and Parameters in Control Protocol . . . . . 20
3.5.1. Setup and Setup State Report messages . . . . . . . . 20
3.5.2. OAM . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.5.3. Forwarding State and Forwarding State Report messages 21
3.5.4. Flow Identifying Methods . . . . . . . . . . . . . . 21
3.5.5. Hop Number . . . . . . . . . . . . . . . . . . . . . 23
3.5.6. Mapping Index, Size and Mapping Index List . . . . . 23
3.5.7. QoS State and life of Time . . . . . . . . . . . . . 23
3.5.8. Authentication . . . . . . . . . . . . . . . . . . . 24
4. Data plane . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.1. Basic Capability . . . . . . . . . . . . . . . . . . . . 24
4.2. Forwarding State and Forwarding State Report . . . . . . 25
4.3. Flow Identification in Packet Forwarding . . . . . . . . 26
4.4. QoS Forwarding State Detection and Failure Handling . . . 26
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5. Other Issues . . . . . . . . . . . . . . . . . . . . . . . . 27
5.1. User and Application driven . . . . . . . . . . . . . . . 27
5.2. Traffic Management in Host . . . . . . . . . . . . . . . 28
5.3. Non-shortest-path . . . . . . . . . . . . . . . . . . . . 28
5.4. Heterogeneous Network . . . . . . . . . . . . . . . . . . 29
5.5. Proxy Control . . . . . . . . . . . . . . . . . . . . . . 29
6. Message Format . . . . . . . . . . . . . . . . . . . . . . . 29
6.1. Setup Msg . . . . . . . . . . . . . . . . . . . . . . . . 29
6.2. Bandwidth Msg . . . . . . . . . . . . . . . . . . . . . . 31
6.3. Burst Msg . . . . . . . . . . . . . . . . . . . . . . . . 31
6.4. Latency Msg . . . . . . . . . . . . . . . . . . . . . . . 31
6.5. Authentication Msg . . . . . . . . . . . . . . . . . . . 32
6.6. OAM Msg . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.7. Forwarding State Msg . . . . . . . . . . . . . . . . . . 32
6.8. Setup State Report Msg . . . . . . . . . . . . . . . . . 33
6.9. Forward State Report Msg . . . . . . . . . . . . . . . . 34
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
8. Security Considerations . . . . . . . . . . . . . . . . . . . 35
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 35
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.1. Normative References . . . . . . . . . . . . . . . . . . 36
10.2. Informative References . . . . . . . . . . . . . . . . . 36
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39
1. Introduction
Recently, more and more new applications for Internet are emerging.
These applications have a common part that is their required
bandwidth is very high and/or latency is very low compared with
traditional applications like most of web and video applications.
For example, AR or VR applications may need a couple of hundred Mbps
bandwidth (throughput) and a low single digit ms latency. Moreover,
the difference of mean bit rate and peak bit rate is huge due to the
compression algorithm [I-D.han-iccrg-arvr-transport-problem].
Some future applications expect that network can provide a bounded
latency service, such as tactile network [Tactile].
With the technology development in 5G and beyond, the wireless access
network is also rising the demand for the Ultra-Reliable and Low-
Latency Communications (URLLC), this also leads to the question if IP
transport can provide such service in Evolved Packet Core (EPC)
network. IP is becoming more and more important in EPC when the
Multi-access Edge Computing (MEC) for 5G will require the cloud and
data service moving closer to eNodeB.
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Following sections will brief the current transport and QoS
technologies, and analyze the limitations to support above new
applications.
A new approach that could provide QoS for transport service will be
proposed. The scope and criteria for the new technology will also be
summarized.
1.1. IP and Transport Technologies
The traditional IP network can only provide the best-effort service.
The transport layer (TCP/UDP) on top of IP are based on this
fundamental architecture. The best-effort-only service has
influenced the transport evolution for quite long time, and results
in some widely accepted assumptions and solutions, such as:
1. The IP layer can only provide the basic P2P (point to point) or
P2MP (point to multi-point) end-to-end connectivity in Internet,
but the connectivity is not reliable and does not guarantee any
quality of service to end-user or application, such as bandwidth,
packet loss, latency etc. Due to this assumption, the transport
layer or application must have its own control mechanism in
congestion and flow to obtain the reliable and satisfactory
service to cooperate with the under layer network quality.
2. The transport layer assumes that the IP layer can only process
all IP flows equally in the hardware since the best effort
service is actually an un-differentiated service. The process
includes scheduling, queuing and forwarding. Thus, the transport
layer must behave nicely and friendly to make sure all flows will
only obtain its own faired share of resource, and no one could
consume more and no one could be starved.
1.2. TCP Solution Analysis
As a most popular and widely used transport technology, TCP traffic
is dominating in Internet from the born of Internet. It is important
to analyze the TCP. This section will brief the TCP, its variation,
and some key factors.
1.2.1. TCP Overview and Evolution
The major functionalities of TCP are flow control and congestion
control.
The flow control is based on the sliding window algorithm. In each
TCP segment, the receiver specifies in the receive window field the
amount of additionally received data (in bytes) that it is willing to
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buffer for the connection. The sending host can send only up to that
amount of data before it must wait for an acknowledgment and window
update from the receiving host.
The congestion control is algorithms to prevent the hosts and network
device fall into congestion state while trying to achieve the maximum
throughput. There are many algorithm variations developed so far.
All congestion control will use some congestion detection scheme to
detect the congestion and adjust the rate of source to avoid the
congestion.
No matter what congestion control algorithm is used, traditionally,
all TCP solutions are pursuing three targets, high efficiency in
bandwidth utilization, high fairness in bandwidth allocation, and
fast convergence to the equilibrium state. [TCP_Targets]
Recently, with the growth of new TCP applications in data center,
more and more solutions were proposed to solve bufferbloat, incast
problems typically happened in data center. These solutions include
DCTCP, PIE, CoDel, FQ-CoDel, etc. In addition to the three
traditional targets mentioned above, these solutions have another
target which is to minimize the latency.
1.2.2. TCP Solution Variants
There are many TCP variants and optimization solutions since TCP was
introduced 40 years ago. We have collected major TCP variants
including typical traditional solution and some new solutions
proposed recently.
The traditional solutions:
These solutions are implemented on host only. They use different
congestion detection and inference mechanism, either based on
packet loss, RTT or both, to dynamically adjust the TCP window to
do the congestion control, such as: TCP-reno [RFC2581], TCP-vegas
[TCP-vegas], TCP-cubic [TCP-cubic], TCP-compound
[I-D.sridharan-tcpm-ctcp], TIMELY [TIMELY], etc
The explicit rate solutions:
These solutions do not use the traditional black box mechanism
executed at host to infer the TCP congestion status, instead, they
rely on the rate calculation on routers to let host adjust
accordingly. Both network devices and hosts must be changed.
Typical solutions are: XCP [I-D.falk-xcp-spec], RCP [RCP]. Note,
we put XCP and RCP as TCP here is referring to the scenario when
XCP and RCP are used with TCP
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The AQM solutions:
These solutions use AQM (Active Queue Management) techniques on
routers to control the buffer size, thus control the congestion
and minimize the latency indirectly. Both network devices and
hosts must be changed. They include: DCTCP [I-D.ietf-tcpm-dctcp],
PIE [I-D.ietf-aqm-pie], CoDel [I-D.ietf-aqm-codel], FQ-CoDel
[I-D.ietf-aqm-fq-codel], etc.
The new concept solutions:
Unlike above categories, these solutions use completely new
concepts and methods to either accurately calculate, or figure out
the optimized rate and latency of TCP, such as: PERC [PERC], BBR
[BBR], PCC [PCC], Fastpass [Fastpass], etc
1.2.3. Throughput Constraint
For the traditional TCP optimization solutions, the efficiency target
is to obtain the high bandwidth utilization as much as possible to
approach the link capacity. The link utilization is defined as the
total throughput of all TCP flows on a network device to the network
bandwidth for links.
For individual TCP flow, its actual throughput is not guaranteed at
all. It depends on many factors, such as TCP algorithm used, the
number of TCP flows sharing the same link, host CPU power, network
device congestion status, delay in transmission, etc.
For traditional TCP, the real throughput for a flow is limited by
three factors: The 1st one is the available maximum throughput at the
physical layer, accounting for maximum theoretical bandwidth, network
load, buffering configuration, maximum segment size, signal strength,
etc; The another is related to congestion control algorithm; The 3rd
is related to the TCP fairness principle. Below we will analyze the
last two factors.
1.2.3.1. By Algorithm
No matter what algorithm is used, The TCP throughput is always
related to some flow and network characteristics, such as the RTT
(Round Trip Time) and PLR (packet loss ratio). For example, TCP-reno
throughput is shown in the formula (3) in [Reno_throughput]; And TCP-
cubic throughput is expressed in formula (21) in [Cubic_throughput].
This limit will prevent the link capacity to be utilized by all TCP
flows. Each TCP flow may only get a few portion of the link
bandwidth as the real throughput for application. Even there is one
TCP flow in a link, the throughput for the TCP could be way below the
link capacity for a network which RTT and PLR are high.
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1.2.3.2. By Fairness Principle
TCP fairness is a de facto principle for all TCP solutions. By this
rule, each router will process all TCP flows equally and fairly to
allocate the required resource to all TCP flows. Different Fair
Queuing algorithms were used, such as Packet based Round Robin, Core-
Stateless Fair Queuing(CSFQ), WFQ, etc. The targets of all
algorithms are to reach the so called max-min fairness [Fairness] of
TCP in terms of bandwidth.
TCP fairness played an important and critical role in saving internet
from collapse caused by congestions since TCP was introduced.
The analysis [RCP] on page 35 has given the formula of the fair share
rate at bottleneck routers, the rate or throughput is capped for
applications which required bandwidth are not satisfied under the
rule of fairness.
1.2.4. Latency Constraint
TCP fairness will not process some TCP flows differently with others,
or there is no TCP micro-flow handling.
As described above, for the traditional solutions and explicit rate
solution, the latency is not considered as a target, thus no latency
guarantee at all.
For AQM solutions and some new concept solutions which try to control
the buffer bloat or flow latency, it can only provide the statistic
bounded latency for all TCP flows. The latency is related to the
queue size and other factors. And the real latency for specific
flow(s) is not deterministic. It could be very small or pretty large
due to the long tail effect if the flow is blocked by other slower
TCP flows.
1.2.5. Summary of TCP Solution
The bandwidth and latency can hardly be satisfied simultaneously
without micro flow handling and management. While trying to get
higher bandwidth, it may lead to more queued packet in router and
result in longer latency. While approaching shorter latency, it may
cause the queue under run, and lead to the lower bandwidth.
As a summary, to support some special TCP applications that are very
sensitive to bandwidth and/or latency, we need to handle those TCP
flows differently with others, and the TCP fairness must be relaxed
for these scenarios.
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It must be noted that the fairness based transport service could
satisfy most of the applications, and it is the most efficient and
economical way for hardware implementation and the network bandwidth
efficiency.
When providing some TCP flows with differentiated service, the
traditional transport service must be able to coexist with the new
service. The resource partitioning between different service is a
operation and management job for service provider.
1.3. Other Solution Analysis
DiffServ
DiffServ [DiffServ] or Differentiated services is a network
architecture that specifies a simple, scalable and coarse-grained
mechanism for classifying and managing network traffic and
providing QoS on modern IP networks. DiffServ is designed to
support the QoS of aggregated traffic and normally is deployed in
Service Provider networks. End user application cannot directly
use DiffServ.
IntServ
IntServ [IntServ] or integrated services specifies more fine-
grained QoS, which is often contrasted with DiffServ's coarse-
grained control system. IntServ definitely can support the
applications requiring special QoS guarantee if it is deployed in
a network, supported by Host OS and integrated with application.
However, IntServ works on a small-scale only. When you scale up
the network, it is difficult to keep track of all of the
reservations and session states. Thus, IntServ is not scalable.
Another problem of IntServ is it is not application driven,
tedious provisioning cross different network must be done earlier.
The provisioning is slow and hard to maintain.
MPLS-TE
MPLS-TE can provide aggregated QoS or fine-grained QoS service for
different class of traffic. Similar to DiffServ, MPLS-TE is
majorly used for service providers network. It requires extra
protocol sets like LDP, MPLS-TE, etc to operate. It is not
practical to extend MPLS-TE to end user's desktop.
1.4. New approach
1.4.1. IP Transport with quality of service
Semiconductor chip technology has advanced a lot for last decades,
the widely used network process can not only forward the packet in
line speed, but also support fast packet processing for other
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features, such as Qos for DiffServ/MPLS, Access Control List (ACL),
fire wall, Deep Packet Inspection (DIP), etc. To treat some TCP/IP
flows differently with others and give them specified resource are
feasible now by using network processor.
Network processor is also able to do the general process to handle
the simple control message for traffic management, such as signaling
for hardware programming, congestion state report, OAM, etc.
This document proposes a mechanism to provide the capability of IP
network to support the transport layer with quality of service. The
solution is based on the QoS implemented in network processor. the
proposal of the document is composed of two parts:
1. Control plane, it explains a transport control sub-layer for IP,
the details of control mechanism.
2. Data plane, the realization of QoS in data forwarding, QoS and
error handling.
1.4.2. Design targets
The new transport service is expected to satisfy following criteria:
1. End user or application can directly use and control the new
service
2. The new service can coexist with the current transport service
and is backward compatible.
3. The service provider can manage the new service.
4. Performance and scalability targets of new service are practical
for vendors to achieve.
5. The new service is transport agnostic. Both TCP, UDP and other
transport protocols on top of IP can use it
1.4.3. Scope and assumption
The initial aim is to propose a solution for IPv6.
To limit the scope of the document and simplify the design and
solution, the following constraints are given.
1. The transport with QoS is aimed to be supplementary to the
regular transport service. At the current situation, It is
targeted for the applications that are bandwidth and/or latency
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sensitive. It is not intended to replace the TCP variants that
have been proved to be efficient and successful for current
applications.
2. The new service is limited within one administrative domain, even
it does not exclude the possibilities to extend the mechanism for
inter-domain scenarios. Thus, the security and other inter-
domain requirements are not critical. The basic security is good
enough, the inter-domain SLA, accounting and other issues are not
discussed.
3. Due to high bandwidth requirement of new service for individual
flow, the total number of the flows with the new service cannot
be high for a port, or a system. From another point of view, the
new service is targeted for the application that really needs it,
the number of supported applications/users are under controlled
and cannot be unlimited. So, the scalability requirement for the
new service is limited.
4. The new service must coexist with the regular transport service
in the same hardware, and backward compatible. Also, a transport
flow can switch without the service interruption between the
regular transport support and new service.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2.1. Definitions
E2E
End-to-end
EH
IPv6 Extension Header or Extension Option
QoS
Quality of Service
OAM
Operation and Management
In-band Signaling
In telecommunications, in-band signaling is the sending of
control information within the same band or channel used for
voice or video.
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Out-of-band Signaling
out-of-band signaling is that the control information sent over
a different channel, or even over a separate network.
IP flow
For non-IPSec, a IP flow is identified by the source,
destination IP address, the protocol number, the source and
destination port number.
IP path
A IP path is the route that IP flow will traverse. It could be
the shortest path determined by routing protocols (IGP or BPG),
or the explicit path decided by another management entity, such
as a central controller, or Path Computation Element (PCE)
Communication Protocol (PCEP), etc
QoS channel
A forwarding channel that the QoS is guaranteed, it provides an
additional QoS service to the normal IP forwarding. A QoS
channel can be used for one or multiple IP flows depends on the
granularity of in-band signaling.
Cir
Committed Information Rate, this is the guaranteed bandwidth
Pir
Peak Information Rate. this is the up limit bandwidth. Whether
a flow can reach the PIR depends on the implementation. To use
resource more efficiently, the system normally does not
guarantee the PIR, but allow the sharing of resource between
flows.
HbH-EH
IPv6 Hop-by-Hop Extension Header
Dst-EH
IPv6 Destination Extension Header
HbH-EH-aware node
Network nodes that are configured to process the IPv6 Hop-by-
Hop Extension Header
3. Control plane
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3.1. Sub-layer in IP for transport control
In order to provide some new features for the upper layer above IP,
it is very useful to introduce an additional sub-layer, Transport
Control, between layer 3 (IP) and layer 4 (TCP/UDP). The new layer
belongs to the IP, and is present only when the system needs to
provide extra control for the upper layer, in addition to the normal
IP forwarding. Fig 1. illustrates a new stack with the sub-layer.
+=========================+
| APP |
+=========================+
| TCP/UDP |
+=========================+
| Transport Ctl |
+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP |
+=========================+
| Network Access |
+=========================+
Figure 1: The new stack with a sub-layer in Layer 3
The new sub-layer is always bound with IP layer and can provide a
support of the features for upper layer, such as:
In-band Signaling
The IP header with the new sub-layer can carry the signaling
information for the devices on the IP path. The information may
include all QoS related parameters used for hardware programming.
Congestion control
The congestion state in each device on the path can be detected
and notified to the source of flows by the sub-layer; The dynamic
congestion control instruction can also be carried by the sub-
layer and examined by network devices on the IP path.
IP Path OAM
The OAM instruction can be carried in the sub-layer, and the OAM
state can be notified to the source of flows by the sub-layer.
The OAM includes the path and device property detection, QoS
forwarding diagnosis and report.
IPv6 can realize the sub-layer easily by the IPv6 extension header
[RFC8200].
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IPv4 could use the IP option for the purpose of the sub-layer. But
due to the limit size of the IP option, the functionalities,
scalability of the layer is restricted.
The document will focus on the solution for IPv6 by using different
IPv6 extension header.
The control plane of the propose comprises of IP in-band signaling,
and the detailed control mechanisms.
3.2. IP In-band signaling
There is no definition for IP in-band signaling. From the point of
view of similarity to traditional telecommunication technology, the
In-band signaling for IP is that the IP control messages are sharing
some common header information as the data packet.
In this document, we introduce three types of "in-band signaling" for
different signaling granularity:
Flow level In-band Signaling
The control message and data packet share the same flow
identification. The flow identification could be 5 tuples for non
IPSec IPv6 packet: the source, destination IP address, protocol
number, source and destination port number, and also could be 3
tuples for IPSec IPv6 packet: the source, destination IP address
and the flow label. For the flow level in-band signaling, the
signaling is for the individual IP flow, and there is no
aggregation at all.
Address level In-band Signaling
The control message and data packet share the same source,
destination IP address, but with different protocol number. This
is the scenario that the signaling is for the aggregated flows
which have the same source, destination address. i.e, All TCP/UDP
flows between the same client and same server (only one address
for client and one for server)
Transport level In-band Signaling
The control message and data packet share the same source,
destination IP address, protocol number, but with different source
or destination port number (non-IPSec) or different flow label
(IPSec). This is the situation that the signaling is for the
aggregated TCP or UDP flows that started and terminated at the
same IP addresses.
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Using In-band signaling, the control message can be embedded into any
data packet, this can bring up some advantages that other methods can
hardly provide:
Diagnosis
The in-band signaling message takes the same path, same hops, same
processing at each hop as the data packet, this will make the
diagnosis for both signaling and data path easier.
Simplicity
The in-band signaling message is forwarded with the normal data
packet, it does not need to run a separate protocol. This will
dramatically reduce the complexity of the control.
Performance and scalability
Due to the simplicity of in-band signaling for control, it is
easier to provide a better performance and scalability for a new
future.
Note, the requirement of IP in-band signaling was proposed before by
John Harper [I-D.harper-inband-signalling-requirements]. And the in-
band QoS signaling for IPv6 was simply discussed in
[I-D.roberts-inband-qos-ipv6]. Unfortunately, both works did not
continue.
This document not only gives detailed solution for in-band signaling,
but also try to address issues raised for the previous proposal, such
as security, scalability and performance. Finally, experiments with
proprietary hardware and chips are given in a presentation.
3.3. Control mechanism
The in-band signaling must be cooperated with a control method to
achieve the QoS control. There are two categories of control, one is
the closed-loop control and another is the open-loop control.
1. Closed-loop control is that the in-band signaling is sent in one
direction and the feedback will return in the reverse direction.
For example, the closed-loop control can be achieved by inserting
the signaling information into a data packet sent in one
direction, and the feedback information is carried in the data
packet in reverse direction. The transport service with bi-
direction data flow can use this mechanism, such as TCP and
point-to-point UDP. In closed-loop control, a signaling message
in one direction is processed at each router on the path. When
the signaling message reaches the destination, the signaling
message is processed by the protocol stack in the host, and the
report information is generated. The report information is then
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embedded into the flow data packet in the reverse direction and
return to the host of the signaling source.
2. Open-loop control is that the in-band signaling is sent
periodically in one direction without any feedback. The
transport service with uni-direction data flow can use this
mechanism, such as multicast by UDP. The transport service with
bi-directional data flow can also use this mechanism when the
simplicity of the control is wanted, i.e. no control feedback
needed.
For both closed-loop and open-loop control, the signaling message for
one direction is for the QoS programming for the direction. For
example, the TCP-SYN or TCP data packet from client to server can
carry the in-band signaling message to program the QoS for the
direction of client to service. TCP-SYNACK or TCP data packet from
server to client can carry the in-band signaling message to program
the QoS for the server to client direction
Due to the nature that symmetric IP path between any source and
destination cannot be guaranteed, in closed-loop control, the
feedback information may take the different path as the in-band
signaling path. The in-band signaling must not depend on the
feedback information to accomplish the signaling work, such as the
programming of hardware. This is one of the difference between in-
band signaling and RSVP protocol.
For this document, we will only discuss the detailed mechanism for
closed-loop control for TCP.
3.4. IPv6 Approach
The IPv6 In-band signaling could be realized by using the IPv6
extension header.
There are two types of extension header used for the purpose of
transport QoS control, one is the hop-by-hop EH (HbH-EH) and another
is the destination EH (Dst-EH).
The HbH-EH may be examined and processed by the nodes that are
explicitly configured to do so [RFC8200]. We call this nodes as HbH-
EH-aware nodes in document below. It is used to carry the QoS
requirement for dedicated flow(s) and then the information is
intercepted by HbH-EH-aware nodes on the path to program hardware
accordingly.
The destination EH will only be examined and processed by the
destination device that is associated with the destination IPv6
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address in the IPv6 header. This EH is used to send the QoS related
report information directly to the source of the signaling at other
end.
3.4.1. Basic Control Scenarios for TCP
The finest grained QoS for TCP is flow level, this document will only
focus on the solution of the flow level in-band signaling and its
data plane. Other two types, address level and transport level QoS
for TCP are briefly discussed in section 5.3.
The feature of TCP with flow level QoS comprises following control
scenarios:
1. Setup: The setup is combined with the TCP 3-hand shaking, or any
two directional TCP packets. When used with TCP 3-hand shaking,
the 1st signaling embedded into HbH-EH is sent with TCP-SYN. It
will be processed at HbH-EH-aware nodes on the path from source
to destination. The signaling message includes the QoS
requirements, such as max/min bandwidth, burst size, the latency,
and the setup state. The setup state message is updated at HbH-
EH-aware nodes to include the QoS programming and provisioning
result and the necessary hardware reference information for IP
forwarding with QoS. The 2nd signaling message is the TCP-SYNACK
from server side, it includes the setup report message encoded as
the Dst-EH. The setup report message is from the 1st TCP-SYN
which represents the setup results on all HbH-EH-aware nodes on
the path. The setup can even be started after TCP is established
whenever the QoS service is required.
2. Dynamic control: this scenario is for the situation that previous
QoS programming must be refreshed, modified or re-programmed.
Normally, the signaling message can be embedded into HbH-EH for
any TCP data packet or TCP-ACK packet. There are couple cases
that the dynamic control is needed.
HW state refreshing
The HW state for QoS programming is data driven (see
Section 4.1 for details). Its state will be refreshed if
there is a data packet received. If there is no data received
for a pre-configured time, the HW programming will be erased
and the resource will be released.
HW programming modification
The HW QoS parameters can be modified if a new in-band
signaling message is received and the embedded parameters are
different with the old one that was used to program the HW.
Section 3.4.2 will explain more about this scenario.
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HW programming repairing
The IP path may be changed due to rerouting, link or node
failures. This may result in the HW QoS programming failure.
To repair any QoS programming failure, the new in-band
signaling message can be embedded into any data packet and
sent to the destination. All hops on the new path will be
reprogramed with the QoS parameters. Section 4.4 has more
detailed discussion.
3. Congestion Control: For TCP protocol, if IP layer can provide a
certain level of quality service guarantee, the congestion
control algorithm will be impacted a lot. As for what is the new
congestion control, it depends on the quality service
implementation in hardware and the behavior of the application.
This is simply discussed in section 5.2.
3.4.2. Details of In-band Signaling for TCP
This document introduces following type of message for in-band
signaling and associated data forwarding, the detailed format of
messages is expressed in Section 6,
o Setup: This is for the setup of QoS channel through the IP path.
o Bandwidth: This is the required bandwidth for the QoS channel. It
has minimum (CIR) and maximum bandwidth (PIR).
o Latency: This is the required latency for the QoS channel, it is
the bounded latency for each hop on the path. This is not the end
to end latency.
o Burst: This is the required burst for the QoS channel, it is the
maximum burst size.
o Authentication: This is the security message for a in-band
signaling.
o OAM: This is the Operation and Management message for the QoS
channel.
o Setup State Report: This is the state report of a setup message.
o Forwarding State: This is the forwarding state message used for
data packet.
o Forwarding State Report: This is the forwarding state report of a
QoS channel.
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There are three scenarios of QoS signaling for TCP session setup with
QoS
1. Upstream: This is for the direction of client to server. A
application decides to open a TCP session with upstream QoS (for
uploading), it will call TCP API to open a socket and connect to
a server. The client host will form a TCP SYN packet with the
HbH-EH in the IPv6 header. The EH includes Setup message and
Bandwidth message, and optionally Latency, Burst, Authentication
and OAM messages. The packet is forwarded at each hop. Each
HbH-EH-aware nodes will process the signaling message to finish
the following tasks before forwarding the packet to next hop:
* Retrieve the QoS parameters to program the Hardware, it
includes: FL, Time, Bandwidth, Latency, Burst
* Update the field in the EH, it includes: Hop_number,
Total_latency, and possibly Mapping Index List
When the server receives the TCP SYN, the Host kernel will also
check the HbH-EH while punting the TCP packet to the TCP stack
for processing. If the HbH-EH is present and the Report bit is
set, the Host kernel must form a new Setup State Report message,
all fields in the message must be copied from the Setup message
in the HbH-EH. When the TCP stack is sending the TCP-SYNACK to
the client, the kernel must add the Setup State Report message as
a Dst-EH in the IPv6 header. After this, the IPv6 packet is
complete and can be sent to wire; When the client receives the
TCP-SYNACK, the Host kernel will check the Dst-EH while punting
the TCP packet to the TCP stack for processing. If the Dst-EH is
present and the Setup State Report message is valid, the kernel
must read the Setup State Report message. Depending on the setup
state, the client will operate according to description in
section 5.1
2. Downstream: This is for the direction of server to client. A
application decides to open a TCP session with downstream QoS
(for downloading), it will call TCP API to open a socket and
connect to a server. The client host will form a TCP SYN packet
with the Dst-EH in the IPv6 header. The EH includes Bandwidth
message, and optionally Latency, Burst messages. The packet is
forwarded at each hop. Each hop will not process the Dst-EH.
When the server receives the TCP SYN, the Host kernel will check
the Dst-EH while punting the TCP packet to the TCP stack for
processing. If the Dst-EH is present, the Host kernel will
retrieve the QoS requirement information from Bandwidth, Latency
and Burst message, and check the QoS policy for the user. If the
user is allowed to get the service with the expected QoS, the
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server will form a Setup message similar to the case of client to
server, and add it as the HbH-EH in the IPv6 header, and send the
TCP-SYNACK to client. Each HbH-EH-aware nodes on the path from
server to client will process the message similar to the case of
client to server. After the client receives the TCP-SYNACK, The
client will send the Setup State Report message to server as the
Dst-EH in the TCP-ACK. Finally the server receives the TC-ACK
and Setup State Report message, it can send the data to the
established session according to the pre-negotiated QoS
requirements.
3. Bi-direction: This is the case that the client wants to setup a
session with bi-direction QoS guarantee. The detailed operations
are actually a combination of Upstream and Downstream described
above.
After a QoS channel is setup, the in-band signaling message can still
be exchanged between two hosts, there are two scenarios for this.
1. Modify QoS on the fly: When the pre-set QoS parameters need to be
adjusted, the application at source host can re-send a new in-
band signaling message, the message can be embedded into any TCP
packet as a IPv6 HbH-EH. The QoS modification should not impact
the established TCP session and programmed QoS service. Thus,
there is no service impcted during the QoS modification.
Depending on the hardware performance, the signaling message can
be sent with TCP packet with different data size. If the
performance is high, the signaling message can be sent with any
TCP packet; otherwise, the signaling message should be sent with
small size TCP packet or zero-size TCP packet (such as TCP ACK).
Modification of QoS on the fly is a very critical feature for the
so called "Application adaptive QoS transport service". With
this service, an application (or the proxy from a service
provider) could setup an optimized CIR for different stage of
application for the economical and efficient purpose. For
example, in the transport of compressed video, the I-frame has
big size and cannot be lost, but P-frame and B-frame both have
smaller size and can tolerate some loss. There are much more
P-frame and B-frame than I-frame in videos with smooth changes
and variations in images [I-D.han-iccrg-arvr-transport-problem].
Based on this characteristics, application can request a
relatively small CIR for the time of P-frame and P-frame, and
request a big CIR for the time of I-frame.
2. Repairing of the QoS channel: This is the case the QoS channel
was broken and need to be repaired, see section 4.4.
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3.5. Key Messages and Parameters in Control Protocol
The detailed message format is described in the section 6, the
detailed explanation of key messages and parameters are below:
3.5.1. Setup and Setup State Report messages
Setup is the message used for following purpose:
o Setup the QoS channel for a TCP when the TCP session is
establishing.
o Dynamic Control of the QoS channel for a established TCP session.
See section 3.4.1
Setup message is intended to program the hardware for QoS channel on
the IP path from the source to the destination expressed in IPv6
header. It is embedded as the HbH-EH in an appropriate TCP packet
and will be processed at each HbH-EH-aware node. For the simplicity,
performance and scalability purpose, we can configure some hop to do
the processing and some hops do not. For different QoS requirement
and scenarios, different criteria can be used for the configuration
of the hop to be HbH-EH-aware node, below are some factor to
consider:
o Reserved bandwidth is required: The throttle router is the
critical point to be configured to process the hop-by-hop EH for
the bandwidth reservation. The throttle router is the device that
a interested TCP session cannot get the enough bandwidth to
support its application. The regular throttle routers include the
BRAS (broadband remote access server) in broadband access network,
the PGW (PDN Gateway) in LTE network, the TOR (Top of Rack) in
data center. In more general case, any routers which aggregate
traffic may become as a throttle router. Moreover, the direction
of congestion must be considered. Normally, the congestion
happens on the direction that more than one flows from multiple
ingress links are aggregated and sent to one egress link. For
other devices that the interested TCP session can get the enough
bandwidth do not need to process the hop-by-hop EH.
o Bounded latency is required: In theory, each router and switch
could contribute some delay to the end-to-end latency, but the
throttle router will contribute more than non-throttle routers,
and slow device will contribute more than fast device. We can use
OAM to detect the latency contribution in a network, and configure
those worst-cast devices to process the HbH-EH.
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Setup State Report message is the message sent from the destination
host to the source host (from the point of view of the Setup
message). The message is embedded into the Dst-EH in any data
packet. The Setup State Report in the message is just a copy from
the Setup message received at the destination host for a typical TCP
session. The message is used at the source host to forward the
packet later and to do the congestion control.
3.5.2. OAM
OAM is a special in-band signaling message used for detection and
diagnosis. It can be used before and after a QoS channel is
established. Before a QoS channel is established, OAM message can be
added as a HbH-EH to any IPv6 packet and used to detect:
o IP path properties: Total hop number that is HbH-EH-aware node;
The IP address of each HbH-EH-aware node.
o Static properties at each HbH-EH-aware node: Protocol version;
Supported Flow identifying methods; Mapping index size; Supported
configuration range of bandwidth, latency, forwarding QoS state
time.
o Financial properties at each HbH-EH-aware node: Unit price for
bandwidth; Unit price for service duration; Price for different
latency.
After a QoS channel is established, OAM message can also be added as
a HbH-EH to any IPv6 packet and used to detect and diagnose failures:
o IP path dynamic properties: Total end to end latency
o Dynamic properties at ach HbH-EH-aware node: Queue size; Remained
bandwidth; Dropped packet number by different reasons.
o The detailed QoS forwarding failure reason.
3.5.3. Forwarding State and Forwarding State Report messages
Forwarding State and Forwarding State Report messages are used for
data plane, See section 4.2.
3.5.4. Flow Identifying Methods
This is a parameter to program the HW for the flow identifying
method. It is used for the QoS granularity definition and flow
identification for QoS process. The QoS is enforced for a group of
flows or a dedicated flow that can be identified by the same flow
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identification. The QoS granularity is determined by the flow
identification method during the setup and packet forwarding process.
There are three levels of QoS granularities: Flow level, Address
level and transport level. Each level of QoS granularity is realized
by corresponding in-band signaling. The document focus on the flow
level in-band signaling, other two level in-band signaling are
discussed in the section 5.3.
There are two ways for the flow identifying method. One is by the
tuples in IP header, another is by a local significant number ( see
mapping index) generated and maintained in a router. When "Mapping
Index Size" (Mis) is zero, it means the "Flow identification method"
(FI) is used for both control plane and data plane. When "Mis" is
not zero, it means "FI" is only used in signaling, and the data plane
will only use the "Mapping Index".
There are four types for "Flow identification method":
1. Individual Flow: Non-IPSec case: flow is identified by source and
destination address, source and destination port number, and
protocol number; IPSec case: flow is identified by source and
destination address, flow label. For both case, FI = 0; the
associated QoS is flow level, and QoS is guaranteed for a
dedicated IP flow.
2. TCP flows: flow is identified by source and destination address,
and TCP protocol number. The associated QoS is transport level,
and QoS is guaranteed for TCP flows that have the same source and
destination address. For this case, FI=1.
3. UDP flows: flow is identified by source and destination address,
and UDP protocol number. The associated QoS is transport level,
and QoS is guaranteed for UDP flows that have the same source and
destination address. For this case, FI=2.
4. All flows: flow is identified by source and destination address.
The associated QoS is address level, and QoS is guaranteed for
all IP flows that have the same source and destination address.
For this case, FI=3
The use of local generated number to identify flow is to speed up the
flow lookup and QoS process for data plane. The number could be the
MPLS label or a local tag for a MPLS capable router. The difference
between this method and the MPLS switch is that there is no MPLS LDP
protocol running and the IP packet does not need to be encapsulated
as MPLS packet at the source host. When the MPLS label is used, the
"Mapping Index Size" is 20 bits.
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3.5.5. Hop Number
This is a parameter for the total number of hop that is HbH-EH-aware
node on the path. it is the field "Hop_num" in Setup message. It is
used to locate the bit position for "Setup State" and the "Mapping
Index" in "Mapping Index List". The value of "Hop_num" must be
decremented at each hop. And at the receive host of the in-band
signaling, the Hop_num must be zero.
The source host must know the exact hop number, and setup the initial
value in the Setup message. The exact hop number can be detected by
the OAM message.
3.5.6. Mapping Index, Size and Mapping Index List
Mapping Index is the local significant number generated and
maintained in a router, and The "Mapping Index List" is just a list
of "Mapping Index" for all hops that are HbH-EH-aware nodes on the IP
path.
Mapping Index Size is the size for each mapping index in the Mapping
Index List. The source host must know Mapping Index Size, and setup
the initial value in the Setup message. The exact Mapping Index Size
can be detected by the OAM message.
When a router receives a HbH-EH, it may generate a mapping index for
the flow(s) that is defined by the Flow Identifying Method in "FL".
Then the router must attach the mapping index value to the end of the
Mapping Index List. After the packet reaches the destination host,
the Mapping Index List will be that the 1st router's mapping index as
the list header, and the last router's mapping index as the list
tail.
3.5.7. QoS State and life of Time
After the chip is programmed for a QoS, a QoS state is created. The
QoS state life is determined by the "Time" in the Setup message.
Whenever there is a packet processed by a QoS state, the associated
timer for the QoS state is reset. If the timer of a QoS state is
expired, the QoS state will be erased and the associated resource
will be released.
In order to keep the QoS state active, a application at source host
can send some zero size of data to refresh the QoS state.
When the Time is set to zero, it means the life of the QoS State will
be kept until the de-programming message is received.
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3.5.8. Authentication
The in-band signaling is designed to have a basic security mechanism
to protect the integrity of a signaling message. The Authentication
message is to attach to a signaling message, the source host
calculates the harsh value of a key and all invariable part of a
signaling message (Setup message: ver, FI, R, Mis, P, Time; Bandwidth
message, Latency message, Burst message). The key is only known to
the hosts and all HbH-EH-aware nodes. The securely distribution of
the key is out the scope of the document
4. Data plane
To support the QoS feature, there are couple of important
requirements and schemes for implementations. These include the
basic capability for the hardware, the scheme for the data
forwarding, QoS processing, state report, etc.
Section 4.1 will talk about the basic capability for data plane, and
section 4.2 will discuss the messages used for data plane after the
QoS channel is established.
4.1. Basic Capability
The document only proposes the protocol used for control, and it is
independent of the implementation of the system. However, to achieve
the satisfactory targets for performance and scalability, the
protocol must be cooperated with capable hardware to provide the
desired fine-grained QoS for different transport.
In our experiment to implement the feature for TCP, we used a network
processor with traffic management feature. The traffic management
can provide the fine-grained QoS for any configured flow(s).
Following capabilities are RECOMMENDED:
1. The in-banding signaling is processed in network processor
without punting to controller CPU for help
2. The QoS forwarding state is kept and maintained in network
processor without the involvement from controller CPU.
3. The QoS state has a life of a pre-configured time and will be
automatically deleted if there is no data packet processed by
that QoS state. The timer can be changed on the fly.
4. The QoS forwarding does not need to be done at the controller
CPU, or so called slow path. It is at the same hardware as the
normal IP forwarding. For any IP packet, the QoS forwarding is
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executed first. Normal forwarding will be executed if there is
no QoS state associated with the identification of the flow.
5. The QoS forwarding and normal forwarding can be switched on the
fly.
4.2. Forwarding State and Forwarding State Report
After the QoS is programmed by the in-band signaling, the specified
IP flows can be processed and forwarded for the QoS requirement.
There are two ways for host to use the QoS channel for associated TCP
session:
1. Host directly send the IP packet without any changes to the
packet, this is for the following cases:
* The hardware was programmed to use the tuples in IP header as
identification for QoS process (Mis = 0), and
* The packet does not function to collect the QoS forwarding
state on the path.
2. Host add the Forward State message into a data packet's IP header
as HbH-EH and send the packet, this is for the cases:
* The hardware was programmed to use the mapping index as
identification for QoS process (Mis != 0).
* The hardware was programmed to use the tuples in IP header as
identification for QoS process (Mis = 0), and the data packet
functions to collect the QoS forwarding state on the path.
This is the situation that host wants to detect the QoS
forwarding state for the purpose of failure handling (See
section 4.3).
Forwarding State message format is shown in the Section 6.7. It is
used to notify the mapping index and also update QoS forwarding state
for the hops that are HbH-EH-aware nodes.
After Forwarding State message is reaching the destination host, the
host is supposed to retrieve it and form a Forwarding State Report
message, and carry it in any data packet as the Dst-EH, then send to
the host in the reverse direction.
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4.3. Flow Identification in Packet Forwarding
Flow identification in Packet Forwarding is same as the QoS channel
establishment by Setup message. It is to forward a packet with a
specified QoS process if the packet is identified to be belonging to
specified flow(s).
There are two method used in data forwarding to identify flows:
1. Hardware was programmed to use tuples in IP header implicitly.
This is indicated by that the "Mis" is zero or the Mapping index
is not used. When a packet is received, its tuples are looked up
according to the value of "FI". If there is a QoS table has
match for the packet, the packet will be processed by the QoS
state found in the QoS table. This method does not need any EH
added into the data packet unless the data packet function to
collect the QoS forwarding state on the path. See section 4.3
2. Hardware was programmed to use mapping index to identify flows.
This is indicated by that the "Mis" is not zero. When a packet
is received, the mapping index associated with the hop is
retrieved and looked up for the QoS table. If it has match for
the packet, the packet will be processed by the QoS state entry
found in the QoS table.
4.4. QoS Forwarding State Detection and Failure Handling
QoS forwarding may be failed due to different reasons:
1. Hardware failure in HbH-EH-aware node.
2. IP path change due to link failure, node failure or routing
changes; And the IP path change has impact to the HbH-EH-aware
node.
3. Network topology change; and the change leads to the changes of
HbH-EH-aware nodes.
Application may need to be aware of the service status of QoS
guarantee when the application is using a TCP session with QoS. In
order to provide such feature, the TCP stack in the source host can
detect the QoS forwarding state by sending TCP data packet with
Forwarding State message coded as HbH-EH. After the TCP data packet
reaches the destination host, the host will copy the forwarding state
into a Forwarding State Report message, and send it with another TCP
packet (for example, TCP-ACK) in reverse direction to the source
host. Thereafter, the source host can obtain the QoS forwarding
state on all HbH-EH-aware nodes.
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A host can do the QoS forwarding state detection by three ways: on
demand, periodically or constantly.
After a host detects that there is QoS forwarding state failure, it
can repair such failure by sending another Setup message embedded
into a HbH-EH of any TCP packet. This repairing can handle all
failure case mentioned above.
If a failure cannot be repaired, host will be notified, and
appropriate action can be taken, see section 5.1
5. Other Issues
Above document only covers the details for the QoS support of
individual TCP session by using the flow level in-band signaling.
Due to the extensive scope of in-band signaling, there are many other
associated issues for IP transport control. Below lists some of
them, and we only brief the solution but do not go to details.
The details of each topic can be expressed in other drafts.
5.1. User and Application driven
The QoS transport service is initiated and controlled by end user's
application. Following tasks are done in host
1. The detailed QoS parameters in in-band signaling is set by end
user application. New socket option must be added, the option is
a place holder for QoS parameters (Setup, Bandwidth, etc), Setup
State Report and Forwarding State Report messages.
2. The Setup State Report and Forwarding State Report message
received at host are processed by transport service in kernel.
The Setup State Report message processed at host can result in
the notification to the application whether the setup is
successful. If the setup is successful, the application can
start to use the socket having the QoS support; If the setup is
failed, the application may have three choices:
* Lower the QoS requirement and re-setup a new QoS channel with
new in-band signaling message.
* Use the TCP session as traditional transport without any QoS
support.
* Lookup the service provider for help to locate the problem in
network.
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5.2. Traffic Management in Host
In order to accommodate in-band signaling and the QoS transport
service, the OS on a host muts be changed in traffic management
related areas. There are two parts for traffic management to be
changed, One is to manage traffic going out a host's shared links.
Another is congestion control for TCP flows:
1. The current traffic management in a host manages traffic from
different TCP/UDP session going out host link(s), in the way
similar to routers to send traffic out. All TCP/UDP sessions
will share the bandwidth for all egress links. For the purpose
to work with the differentiated service provided by under layer
network in bandwidth and latency, the kernel may allocate
expected resource to applications that are using the QoS
transport service. For example, kernel can queue different
packets from different applications or users to different queue
and schedule them in different priority. Only after this change,
some application can use more bandwidth and get less queuing
delay for a link than others.
2. The congestion control in a host manages the behavior of TCP
flow(s). This includes important features like slow start, AIMD,
fast retransmit, selective ACK, etc. To accommodate the benefit
of the QoS guaranteed transport service, the congestion control
will be much simpler. The new congestion control is related to
the implementation of QoS guarantee. Following is a simple
congestion control algorithm assuming that the CIR is guaranteed
and PIR is shared between flows:
* There is no slow start, the TCP can start the traffic at the
rate of CIR.
* The AIMD is kept, but the range of the sawtooth pattern should
be maintained between CIR and PIR.
* Other congestion control features can be kept.
5.3. Non-shortest-path
The above method for the transport service with QoS is for the normal
IP flows passing along the shortest path determined by the IGP or
BGP. However, the IP shortest path may not be the best path in terms
of the QoS. For example, the original IP path may not have enough
bandwidth for a transport QoS service. The latency of the IP path is
not the minimum in the network. There are two problems involved.
One is how to find the best path for a QoS criteria, bandwidth or
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latency. Another is how to setup the transport QoS for a non-
shortest-path.
The 1st problem is out of scope of this document and many
technologies have be discovered or in research.
The 2nd problem can be solved by combining the segment routing and
in-band signaling. The use of the HbH-EH and Dst-EH is independent
of the type of IP path, thus can be used with segment routing for any
path determined by source. Note, the HbH-EH-aware nodes may not be
different as the explicit IPv6 address in the segment routing header.
5.4. Heterogeneous Network
When IP network is crossing a non-IP network, such as MPLS or
Ethernet network, the in-band signaling needs to be interworking with
that network. The behavior, protocol and rules in the interworking
with non-IP network is not the problem this document will address.
More study and research need to be done, and new draft should be
written to solve the problem.
5.5. Proxy Control
It is expected that for a real service provider network, the in-band
signaling will be checked, filtered and managed at a proxy routers.
This will serve following purpose:
1. Proxy can check if a in-band signaling from end user for the SLA
compliance, security and DOS attack prevention.
2. Proxy can collect the statistics for user's TCP flows and check
the in-band signaling for accounting and charging.
3. Proxy can insert and process appropriate in-band signaling for
TCP flows that the host does not support the new feature, and
this can provide the backward compatibility for host to use the
new feature.
6. Message Format
6.1. Setup Msg
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0|ver| FI|R|Mis|P| Time | Hop_num |u| Total_latency |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| State for each hop index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mapping index list for hops |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-. . . +
Type = 0, Setup state;
Version: The version of the protocol for the QoS
FI: Flow identification method,
0: 5 tuples; 1: src,dst,TCP; 2: src,dst,UDP; 3: src,dst
R: If the destination host report the received Setup state to
the src address by Destination EH. 0: dont report; 1: report
Mis: Mapping index size; 0: 0bits, 1: 16bits, 2: 20bits, 3: 32bits
P: Programming the HW for QoS; 0: program HW for the QoS from
src to dst; 1: De-program HW for the QoS from src to dst
Time: The life time of QoS forwarding state in second.
Hop_num: The total hop number on the path set by host. It must be
decremented at each hop after the processing.
u: the unit of latency, 0: ms; 1: us
Total_latency : Latency accumulated from each hop, each hop will
add the latency in the device to this value.
Setup state for each hop index: each bit is the setup state on
each hop on the path, 0: failed; 1: success. The 1st hop is at the
most significant bit.
Mapping index list for hops: the mapping index list for all hops
on the path, each index bit size is defined in Mis. The 1st
mapping index is at the top of the stack. Each hop add its mapping
index at the correct position indexed by the current hop number
for the router.
Figure 2: The Setup message
The Setup message is embedded into the hop-by-hop EH to setup the QoS
in the device on the IP forwarding path. At each hop, if the router
is configured to process the header and to enforce the QoS, it must
retrieve the hardware required information from the header, and then
update some fields in the hader.
To keep the whole setup message size unchanged at each hop, the total
hop number must be known at the source host The total hop number can
be detected by OAM. The mapping index list is empty before the 1st
hop receives the in-band signaling. Each hop then fill up the
associated mapping index into the correct place determined by the
index of the hop.
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6.2. Bandwidth Msg
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1| reserved | Minimum bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type = 1,
Minimum bandwidth : The minimum bandwidth required, or CIR, unit Mbps
Maximum bandwidth : The maximum bandwidth required, or PIR, unit Mbps
Figure 3: The Bandwidth message
6.3. Burst Msg
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 0| Burst size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type = 2,
Burst size : The burst size, unit M bytes
Figure 4: The burst message
6.4. Latency Msg
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 1|u| Latency |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type = 3,
u: the unit of the latency
0: ms; 1: us
Latency: Expected maximum latency for each hop
Figure 5: The Latency message
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6.5. Authentication Msg
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 0 0| MAC_ALG | res | MAC data (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+. . .+
Type = 4,
MAC_ALG: Message Authentication Algorithm
0: MD5; 1:SHA-0; 2: SHA-1; 3: SHA-256; 4: SHA-512
MAC data: Message Authentication Data;
Res: Reserved bits
Size of signaling data (opt_len): Size of MAC data + 2
MD5: 18; SHA-0: 22; SHA-1: 22; SHA-256: 34; SHA-512: 66
Figure 6: The Authentication message
6.6. OAM Msg
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 0 1| OAM_t | OAM_len | OAM data (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+. . .+
Type = 5,
OAM_t : OAM type
OAM_len : 8-bit unsigned integer. Length of the OAM data, in octets;
OAM data: OAM data, details of OAM data are TBD.
Figure 7: The OAM message
6.7. Forwarding State Msg
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 1 0|ver| FI|R|Mis|P| Time | Hop_num |u| Total_latency |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Forwarding state for each hop index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mapping index list for hops |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-. . . +
Type = 6, Forwarding state;
All parameter definitions and process in the 1st row are same in
the setup message.
Forward state for each hop index : each bit is the fwd state on each
hop on the path, 0: failed; 1: success; The 1st hop is at the
most significant bit.
Mapping index list for hops: the mapping index list for all hops on
the path, each index bit size is defined in Mis. The list is from
the setup report message.
Figure 8: The Forwarding State message
6.8. Setup State Report Msg
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 1 1|ver|H|u| Total_latency | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| State for each hop index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mapping index list for hops |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-. . . +
Type = 7, Setup state report;
H: Hop number bit. When a host receives a setup message and form
a setup report message, it must check if the Hop_num in setup
message is zero. If it is zero, the H bit is set to one, and if
it is not zero, the H bit is clear. This will notify the source
of setup message that if the original Hop_num was correct.
Following are directly copied from the setup message:
u, Total_latency;
State for each hop index
Mapping index list for hops.
Figure 9: The Setup State Report message
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6.9. Forward State Report Msg
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0|ver|H|u| Total_latency | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Forwarding state for each hop index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type = 8, Forwarding state report;
H: Hop number bit. When a host receives a Forward State message
and form a Forward State Report message, it must check if the
Hop_num in Forward State message is zero. If it is zero, the H bit
is set to one, and if it is not zero, the H bit is clear.
This will notify the source of Forward State message that if the
original Hop_num was set correct.
Following are directly copied from the Forward State message:
u, Total_latency;
Forwarding State for each hop index
Figure 10: The Fwd State Report message
7. IANA Considerations
This document defines a new option type for the Hop-by-Hop Options
header and the Destination Options header. According to [RFC8200],
the detailed value are:
+-----------+----------------+---------------------+---------------+
| | Binary Value | | |
| Hex Value +----+---+-------+ Description | Reference |
| | act|chg| rest | | |
+-----------+----+---+-------+---------------------+---------------+
| 0x0 | 00 | 0 | 10000 | In-band Signaling | Section 6 |
| | | | | | in this doc |
+-----------+----+---+-------+---------------------+---------------+
Figure 11: The New Option Type
1. The highest-order 2 bits: 00, indicating if the processing IPv6
node does not recognize the Option type, skip over this option and
continue processing the header.
2. The third-highest-order bit: 0, indicating the Option Data does
not change en route.
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3. The low-order 5 bits: 10000, assigned by IANA.
This document also defines a 4-bit subtype field, for which IANA will
create and will maintain a new sub-registry entitled "In-band
signaling Subtypes" under the "Internet Protocol Version 6 (IPv6)
Parameters" [IPv6_Parameters] registry. Initial values for the
subtype registry are given below
+-------+------------+-----------------------------+---------------+
| Type | Mnemonic | Description | Reference |
+-------+------------+-----------------------------+---------------+
| 0 | SETUP | Setup message | Section 6.1 |
+-------+------------+-----------------------------+---------------+
| 1 | BANDWIDTH | Bandwidth message | Section 6.2 |
+-------+------------+-----------------------------+---------------+
| 2 | BURST | Burst message | Section 6.3 |
+-------+------------+-----------------------------+---------------+
| 3 | LATENCY | Latency message | Section 6.4 |
+-------+------------+-----------------------------+---------------+
| 4 | AUTH | Authentication message | Section 6.5 |
+-------+------------+-----------------------------+---------------+
| 5 | OAM | OAM message | Section 6.6 |
+-------+------------+-----------------------------+---------------+
| 6 | FWD STATE | Forward state | Section 6.7 |
+-------+------------+-----------------------------+---------------+
| 7 |SETUP REPORT| Setup state report | Section 6.8 |
+-------+------------+-----------------------------+---------------+
| 8 | FWD REPORT | Forwarding state report | Section 6.9 |
+-------+------------+-----------------------------+---------------+
Figure 12: The In-band Signaling Sub Type
8. Security Considerations
There is no security issue introduced by this document
9. Acknowledgements
We like to thank Huawei's Nanjing research team leaded by Feng Li to
provide the Product on Concept (POC) development and test, the team
member includes Fengxin Sun, Xingwang Zhou, Weiguang Wang. We also
like to thank other people involved in the discussion of solution:
Tao Ma from Future Network Streategy dept.
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10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2581] Allman, M., Paxson, V., and W. Stevens, "TCP Congestion
Control", RFC 2581, DOI 10.17487/RFC2581, April 1999,
<https://www.rfc-editor.org/info/rfc2581>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
10.2. Informative References
[BBR] Neal Cardwell, et al, Google, "BBR Congestion Control",
2016, <https://www.ietf.org/proceedings/97/slides/
slides-97-iccrg-bbr-congestion-control-02.pdf>.
[Cubic_throughput]
Wei Bao, et al. The University of British Columbia,
Vancouver, Canada, IEEE Globecom 2010 proceedings, "A
Model for Steady State Throughput of TCP CUBIC", 2010,
<https://www.researchgate.net/publication/224211021_A_Mode
l_for_Steady_State_Throughput_of_TCP_CUBIC>.
[DiffServ]
wiki, "Differentiated services", 2016,
<https://en.wikipedia.org/wiki/Differentiated_services>.
[Fairness]
Jain, R., et al. DEC Research Report TR-301, "A
Quantitative Measure of Fairness and Discrimination for
Resource Allocation in Shared Computer Systems", 1984,
<http://www1.cse.wustl.edu/~jain/papers/ftp/fairness.pdf>.
[Fastpass]
Jonathan Perry, et al, MIT, "Fastpass: A Centralized
?Zero-Queue? Datacenter Network", 2014,
<http://fastpass.mit.edu/Fastpass-SIGCOMM14-Perry.pdf>.
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[I-D.falk-xcp-spec]
Falk, A., "Specification for the Explicit Control Protocol
(XCP)", draft-falk-xcp-spec-03 (work in progress), July
2007.
[I-D.han-iccrg-arvr-transport-problem]
Han, L. and K. Smith, "Problem Statement: Transport
Support for Augmented and Virtual Reality Applications",
draft-han-iccrg-arvr-transport-problem-01 (work in
progress), March 2017.
[I-D.harper-inband-signalling-requirements]
Harper, J., "Requirements for In-Band QoS Signalling",
draft-harper-inband-signalling-requirements-00 (work in
progress), January 2007.
[I-D.ietf-aqm-codel]
Nichols, K., Jacobson, V., McGregor, A., and J. Iyengar,
"Controlled Delay Active Queue Management", draft-ietf-
aqm-codel-06 (work in progress), December 2016.
[I-D.ietf-aqm-fq-codel]
Hoeiland-Joergensen, T., McKenney, P.,
dave.taht@gmail.com, d., Gettys, J., and E. Dumazet, "The
FlowQueue-CoDel Packet Scheduler and Active Queue
Management Algorithm", draft-ietf-aqm-fq-codel-06 (work in
progress), March 2016.
[I-D.ietf-aqm-pie]
Pan, R., Natarajan, P., Baker, F., and G. White, "PIE: A
Lightweight Control Scheme To Address the Bufferbloat
Problem", draft-ietf-aqm-pie-10 (work in progress),
September 2016.
[I-D.ietf-tcpm-dctcp]
Bensley, S., Eggert, L., Thaler, D., Balasubramanian, P.,
and G. Judd, "Datacenter TCP (DCTCP): TCP Congestion
Control for Datacenters", draft-ietf-tcpm-dctcp-03 (work
in progress), November 2016.
[I-D.roberts-inband-qos-ipv6]
Roberts, L. and J. Harford, "In-Band QoS Signaling for
IPv6", draft-roberts-inband-qos-ipv6-00 (work in
progress), July 2005.
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[I-D.sridharan-tcpm-ctcp]
Sridharan, M., Tan, K., Bansal, D., and D. Thaler,
"Compound TCP: A New TCP Congestion Control for High-Speed
and Long Distance Networks", draft-sridharan-tcpm-ctcp-02
(work in progress), November 2008.
[IntServ] wiki, "Integrated services", 2016,
<https://en.wikipedia.org/wiki/Integrated_services>.
[IPv6_Parameters]
IANA, "Internet Protocol Version 6 (IPv6) Parameters",
2015, <https://www.iana.org/assignments/ipv6-parameters/
ipv6-parameters.xhtml#ipv6-parameters-2>.
[PCC] Mo Dong, et al, University of Illinois at Urbana-
Champaign, Hebrew University of Jerusalem, "PCC: Re-
architecting Congestion Control for Consistent High
Performance", 2014, <https://arxiv.org/abs/1409.7092>.
[PERC] Lavanya Jose, et al, Stanford University, MIT, Microsoft,
"High Speed Networks Need Proactive Congestion Control",
2016, <http://web.stanford.edu/~lavanyaj/papers/
perc-hotnets15.pdf>.
[RCP] Nandita Dukkipati, Ph.D. Thesis, Department of Electrical
Engineering, Stanford University, "Rate Control Protocol
(RCP): Congestion control to make flows complete quickly",
2007,
<http://yuba.stanford.edu/~nanditad/thesis-NanditaD.pdf>.
[Reno_throughput]
Matthew Mathis, et al, Pittsburgh Supercomputing Center,
"The Macroscopic Behavior of the TCP Congestion Avoidance
Algorithm", 1997,
<https://cseweb.ucsd.edu/classes/wi01/cse222/papers/
mathis-tcpmodel-ccr97.pdf>.
[Tactile] JDavid Szabo, et al. Proceedings of European Wireless
2015; 21th European Wireless Conference, "Towards the
Tactile Internet: Decreasing Communication Latency with
Network Coding and Software Defined Networking", 2015,
<http://fastpass.mit.edu/Fastpass-SIGCOMM14-Perry.pdf>.
[TCP-cubic]
Ha, S., Rhee, I., and L. Xu, "CUBIC: A New TCP-Friendly
High-Speed TCP Variant", 2008.
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[TCP-vegas]
Peterson, L., "TCP Vegas: New Techniques for Congestion
Detection and Avoidance - CiteSeer page on the 1994
SIGCOMM paper", 1994.
[TCP_Targets]
Andreas Benthin, Stefan Mischke, University of Paderborn,
"Bandwidth Allocation of TCP", 2004.
[TIMELY] Radhika Mittal, et al. Google, Inc., "TIMELY: RTT-based
Congestion Control for the Datacenter", 2010,
<http://conferences.sigcomm.org/sigcomm/2015/pdf/papers/
p537.pdf>.
Authors' Addresses
Lin Han (editor)
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
Phone: +10 408 330 4613
Email: lin.han@huawei.com
Guoping Li
Huawei Technologies
Beijing
China
Email: liguoping@huawei.com
Boyan Tu
Huawei Technologies
Beijing
China
Email: tuboyan@huawei.com
Xuefei Tan
Huawei Technologies
Beijing
China
Email: tanxuefei@huawei.com
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Frank Li
Huawei Technologies
Nanjing
China
Email: frank.lifeng@huawei.com
Richard Li
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: renwei.li@huawei.com
Jeff Tantsura
Email: jefftant.ietf@gmail.com
Kevin Smith
Vodafone
UK
Email: Kevin.Smith@vodafone.com
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