Internet DRAFT - draft-ietf-spring-ipv6-use-cases
draft-ietf-spring-ipv6-use-cases
Spring J. Brzozowski
Internet-Draft J. Leddy
Intended status: Informational Comcast
Expires: June 21, 2018 C. Filsfils
R. Maglione, Ed.
M. Townsley
Cisco Systems
December 18, 2017
IPv6 SPRING Use Cases
draft-ietf-spring-ipv6-use-cases-12
Abstract
The Source Packet Routing in Networking (SPRING) architecture
describes how Segment Routing can be used to steer packets through an
IPv6 or MPLS network using the source routing paradigm. This
document illustrates some use cases for Segment Routing in an IPv6
only environment.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IPv6 SPRING use cases . . . . . . . . . . . . . . . . . . . . 2
2.1. SPRING in the Small Office . . . . . . . . . . . . . . . 2
2.2. SPRING in the Access Network . . . . . . . . . . . . . . 4
2.3. SPRING in Data Center . . . . . . . . . . . . . . . . . . 4
2.4. SPRING in Content Delivery Networks . . . . . . . . . . . 5
2.5. SPRING in Core networks . . . . . . . . . . . . . . . . . 5
3. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Informative References . . . . . . . . . . . . . . . . . 8
7.2. Normative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Source Packet Routing in Networking (SPRING) architecture leverages
the source routing paradigm. An ingress node steers a packet by
including a controlled set of instructions, called segments, in the
SPRING header. The SPRING architecture is described in
[I-D.ietf-spring-segment-routing]. This document illustrates some
use cases for SPRING/Segment Routing in an IPv6 only environment.
2. IPv6 SPRING use cases
The use cases described in the section do not constitute an
exhaustive list of all the possible scenarios: this section only
includes some of the most common envisioned deployment models for
IPv6 Segment Routing.
In addition to the use cases described in this document, all the
SPRING use cases [RFC7855] are also applicable to the SRv6 data
plane.
2.1. SPRING in the Small Office
An IPv6-enabled small office (SOHO) provides ample globally routed IP
addresses for all devices in the SOHO. An IPv6 small office with
multiple egress points and associated provider-assigned prefixes
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will, in turn, provide multiple IPv6 addresses to hosts. A small
office performing Source and Destination Routing
([I-D.ietf-rtgwg-enterprise-pa-multihoming]) will ensure that packets
exit the SOHO at the appropriate egress based on the associated
delegated prefix for that link.
A SPRING enabled SOHO provides the ability to steer traffic into a
specific path from end-hosts in the SOHO, or from a customer edge
router in the SOHO. If the selection of the source routed path is
enabled at the customer edge router, that router is responsible for
classifying traffic and steering it into the correct path. If hosts
in the SOHO have explicit source selection rules, classification can
be based on source address or associated network egress point,
avoiding the need for DPI-based implicit classification techniques.
If the traffic is steered into a specific path by the host itself, it
is important to know which networks can interpret the SPRING header.
This information can be provided as part of host configuration as a
property of the configured IP address.
The ability to steer traffic to an appropriate egress or utilize a
specific type of media (e.g., low-power, WIFI, wired, femto-cell,
bluetooth, MOCA, HomePlug, etc.) within the home itself are obvious
cases which may be of interest to an application running within a
SOHO.
Steering to a specific egress point may be useful for a number of
reasons, including:
o Regulatory
o Performance of a particular service associated with a particular
link
o Cost imposed due to data-caps or per-byte charges
o Home vs. work traffic in homes with one or more teleworkers, etc.
o Specific services provided by one ISP vs. another
Information included in the SPRING header, whether imposed by the
end-host itself, a customer edge router, or within the access network
of the ISP, may be of use at the far ends of the data communication
as well. For example, an application running on an end-host with
application-support in a data center can utilize the SPRING header as
a channel to include information that affects its treatment within
the data center itself, allowing for application-level steering and
load-balancing without relying upon implicit application
classification techniques at the data-center edge. Further, as more
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and more application traffic is encrypted, the ability to extract
(and include in the SPRING header) just enough information to enable
the network and data center to load-balance and steer traffic
appropriately becomes more and more important.
2.2. SPRING in the Access Network
Access networks deliver a variety of types of traffic from the
service provider's network to the home environment and from the home
towards the service provider's network.
For bandwidth management or related purposes, the service provider
may want to associate certain types of traffic to specific physical
or logical downstream capacity pipes.
This mapping is not the same thing as classification and scheduling.
In the Cable access network, each of these pipes are represented at
the DOCSIS [DOCSIS] layer as different service flows, which are
better identified as differing data links. As such, creating this
separation allows an operator to differentiate between different
types of content and perform a variety of differing functions on
these pipes, such as byte capping, regulatory compliance functions,
and billing.
In a cable operator's environment, these downstream pipes could be a
specific QAM (Quadrature Amplitude Modulation) [QAM], a DOCSIS (Data
Over Cable Service Interface Specification) [DOCSIS] service flow or
a service group.
Similarly, the operator may want to map traffic from the home sent
towards the service provider's network to specific upstream capacity
pipes. Information carried in a packet's SPRING header could provide
the target pipe for this specific packet. The access device would
not need to know specific details about the packet to perform this
mapping; instead the access device would only need to know the
interpretation of the SPRING header and how to map it to the target
pipe.
2.3. SPRING in Data Center
Some Data Center operators are transitioning their Data Center
infrastructure from IPv4 to native IPv6 only, in order to cope with
IPv4 address depletion and to achieve larger scale. In such
environment, source routing, as enabled by Segment Routing IPv6, can
be used to steer traffic across specific paths through the network.
The specific path may also include a given function one or more nodes
in the path are requested to perform.
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In addition one of the fundamental requirements for Data Center
architecture is to provide scalable, isolated tenant networks. In
such scenarios, Segment Routing can be used to identify specific
nodes, tenants, and functions and to build a construct to steer the
traffic across that specific path.
2.4. SPRING in Content Delivery Networks
The rise of online video applications and new, video-capable IP
devices has led to an explosion of video traffic traversing network
operator infrastructures. In the drive to reduce the capital and
operational impact of the massive influx of online video traffic, as
well as to extend traditional TV services to new devices and screens,
network operators are increasingly turning to Content Delivery
Networks (CDNs).
Several studies showed the benefits of connecting caches in a
hierarchical structure following the hierarchical nature of the
Internet. In a cache hierarchy one cache establishes peering
relationships with its neighbor caches. There are two types of
relationship: parent and sibling. A parent cache is essentially one
level up in a cache hierarchy. A sibling cache is on the same level.
Multiple levels of hierarchy are commonly used in order to build
efficient caches architecture.
In an environment, where each single cache system can be uniquely
identified by its own IPv6 address, a list containing a sequence of
the caches in a hierarchy can be built. At each node (cache) in the
list, the presence of the requested content is checked. If the
requested content is found at the cache (cache hits scenario) the
sequence ends, even if there are more nodes in the list; otherwise
next element in the list (next node/cache) is examined.
2.5. SPRING in Core networks
While the overall amount of traffic offered to the network continues
to grow and considering that multiple types of traffic with different
characteristics and requirements are quickly converging over single
network architecture, the network operators are starting to face new
challenges.
Some operators are currently building, or plan to build in the near
future, an IPv6 only native infrastructure for their core network.
These operators are also looking at the possibility to setup an
explicit path based on the IPv6 source address for specific types of
traffic in order to efficiently use their network infrastructure. In
case of IPv6 some operators are currently assigning or plan to assign
IPv6 prefix(es) to their IPv6 customers based on regions/geography,
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thus the subscriber's IPv6 prefix could be used to identify the
region where the customer is located. In such environment the IPv6
source address could be used by the Edge nodes of the network to
steer traffic and forward it through a specific path other than the
optimal path.
The need to setup a source-based path, going through some specific
middle/intermediate points in the network may be related to different
requirements:
o The operator may want to be able to use some high bandwidth links
for specific type of traffic (like video) avoiding the need for
over-dimensioning all the links of the network;
o The operator may want to be able to setup a specific path for
delay sensitive applications;
o The operator may have the need to be able to select one (or
multiple) specific exit point(s) at peering points when different
peering points are available;
o The operator may have the need to be able to setup a source based
path for specific services in order to be able to reach some
servers hosted in some facilities not always reachable through the
optimal path;
o The operator may have the need to be able to provision guaranteed
disjoint paths (so-called dual-plane network) for diversity
purposes
All these scenarios would require a form of traffic engineering
capabilities in an IPv6 only network environment.
3. Contributors
Many people contributed to this document. The authors of this
document would like to thank and recognize them and their
contributions. These contributors provided invaluable concepts and
content for this document's creation.
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Ida Leung
Rogers Communications
8200 Dixie Road
Brampton, ON L6T 0C1
CANADA
Email: Ida.Leung@rci.rogers.com
Stefano Previdi
Cisco Systems
Via Del Serafico, 200
Rome 00142
Italy
Email: sprevidi@cisco.com
Christian Martin
Cisco Systems
Email: martincj@cisco.com
4. Acknowledgements
The authors would like to thank Brian Field, Robert Raszuk, Wes
George, Eric Vyncke, Fred Baker, John G. Scudder, Adrian Farrel,
Alvaro Retana, Bruno Decraene and Yakov Rekhter for their valuable
comments and inputs to this document.
5. IANA Considerations
This document does not require any action from IANA.
6. Security Considerations
This document presents use cases to be considered by the SPRING
architecture and potential IPv6 extensions. As such, it does not
introduce any security considerations. However, there are a number
of security concerns with source routing at the IP layer [RFC5095].
It is expected that any solution that addresses these use cases to
also address any security concerns.
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7. References
7.1. Informative References
[DOCSIS] "DOCSIS Specifications Page",
<http://www.cablelabs.com/news/
new-generation-of-docsis-technology/>.
[I-D.ietf-rtgwg-enterprise-pa-multihoming]
Baker, F., Bowers, C., and J. Linkova, "Enterprise
Multihoming using Provider-Assigned Addresses without
Network Prefix Translation: Requirements and Solution",
draft-ietf-rtgwg-enterprise-pa-multihoming-02 (work in
progress), October 2017.
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing
Architecture", draft-ietf-spring-segment-routing-13 (work
in progress), October 2017.
[QAM] "QAM specification", <ITU-T Recommendation J.83 Annex B
(J.83b)>.
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
of Type 0 Routing Headers in IPv6", RFC 5095,
DOI 10.17487/RFC5095, December 2007,
<https://www.rfc-editor.org/info/rfc5095>.
7.2. Normative References
[RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B.,
Litkowski, S., Horneffer, M., and R. Shakir, "Source
Packet Routing in Networking (SPRING) Problem Statement
and Requirements", RFC 7855, DOI 10.17487/RFC7855, May
2016, <https://www.rfc-editor.org/info/rfc7855>.
Authors' Addresses
John Brzozowski
Comcast
Email: john_brzozowski@cable.comcast.com
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John Leddy
Comcast
Email: John_Leddy@cable.comcast.com
Clarence Filsfils
Cisco Systems
Brussels
BE
Email: cfilsfil@cisco.com
Roberta Maglione (editor)
Cisco Systems
Via Torri Bianche 8
Vimercate 20871
Italy
Email: robmgl@cisco.com
Mark Townsley
Cisco Systems
Email: townsley@cisco.com
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