Internet DRAFT - draft-detti-conet-ip-option
draft-detti-conet-ip-option
Network Working Group A. Detti
Internet-Draft S. Salsano
Intended status: Informational N. Blefari-Melazzi
Expires: December 22, 2013 Univ. of Rome "Tor Vergata"
June 20, 2013
IP protocol suite extensions to support CONET Information Centric
Networking
draft-detti-conet-ip-option-05
Abstract
The Information Centric Networking (ICN) paradigm shifts the focus of
networking from providing connections between hosts to efficiently
providing content to the users. The work on ICN has traditionally
been performed looking at "clean-slate" solutions which aims to
replace IP with a new paradigm. On the other hand, in this memo we
propose an "integration" approach to Information Centric Networking,
i.e. we extend the IP protocol suite by defining a new IP Protocol
type (CONET). Then we propose two ways of carring ICN related
information in IP packets, one uses a new IP Option (both for IPv4
and IPv6), the other one only relies on the IP payload. The ICN
related information is used by network nodes and end nodes to support
networking based on content rather than (or better in addition to)
end-point addresses.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 22, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. ICN information header . . . . . . . . . . . . . . . . . . . 4
3. CONET protocol . . . . . . . . . . . . . . . . . . . . . . . 8
4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. Interest CONET Information Unit (Interest CIU) . . . . . 11
4.1.1. Processing in the End-Node . . . . . . . . . . . . . 11
4.1.2. Processing in the Serving Node . . . . . . . . . . . 11
4.1.3. Processing in the Border Node . . . . . . . . . . . . 12
4.1.4. Processing in the Intermediate Node . . . . . . . . . 12
4.1.5. Processing in the legacy routers . . . . . . . . . . 13
4.2. Named data CONET Information Unit (Named data CIU) . . . 13
4.2.1. Processing in the responding node . . . . . . . . . . 13
4.2.2. Processing in a Border Node . . . . . . . . . . . . . 13
4.2.3. Processing in an Intermediate Node . . . . . . . . . 14
4.2.4. Processing in the legacy routers . . . . . . . . . . 14
5. Forward-by-name framework . . . . . . . . . . . . . . . . . . 14
6. CONET default namespaces . . . . . . . . . . . . . . . . . . 15
7. Two ways of carrying ICN information in IP packets . . . . . 16
7.1. Using CONET IP Option to carry ICN information . . . . . 16
7.2. IPv6 handling of CONET option . . . . . . . . . . . . . . 17
7.3. Comparison among the two ways . . . . . . . . . . . . . . 18
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
9. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
10.1. Normative References . . . . . . . . . . . . . . . . . . 19
10.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 20
Appendix B. Document history . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
In this memo we propose two variants of a solution to support
Information Centric Networking [Koponen07][Jacobson09] in IP
networks. The proposed solution needs a new Internet Protocol Number
to identify the ICN protocol (that we call CONET). The first variant
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of the solution is based on extending the IP protocol by using a new
IP Option called CONET IP option (defined both for IPv4 [RFC0791] and
IPv6 [RFC2460]). The CONET IP option can be used by routers to
support content aware networking, in addition to classical address
based networking. The CONET IP option is used to identify the
content which is the object of the data transfer. Its usage allows
efficient in-network caching and replication of content. This
solution has been described in [CONET11] and was the only one
proposed in previous versions of this draft, up to version 04. The
second variant of the solution carries all ICN related information
within the IP payload, with no need to extend the IP protocol itself.
The CONET reference architecture foresees End-Nodes, Serving Nodes
and CONET nodes (see Figure 1). End-Nodes request for content.
Serving Nodes provide content. CONET nodes: i) forward content
requests from End-Nodes to Serving Nodes; ii) deliver content from
Serving Nodes to End-Nodes; iii) may cache content and therefore
provide it to End-Nodes without contacting the Serving Node. CONET
nodes can be further classified in Border Nodes and Internal nodes.
Border Nodes are able to perform both "forward-by-name" and caching,
Internal nodes are not able to perform "forward-by-name" (but only
plain IP routing) and can only perform caching.
requests for content
------------------->
content is provided
<-------------------
+----+ +----+ +----+
| | --| |------| |
+----+\ / +----+ +----+
\ +----+ +----+ /
----| |------| |/
+----+ +----+
End-Node legacy Intermediate Border Serving
IP router Node Node Node
| |
+---------CONET next hop----------->+
| CONET Sub System (CCS) x | CCS y |
Figure 1: CONET architecture
As shown in Figure 1, the CONET Information Centric Network can be
seen as the inteconnection of CONET Sub Systems (CSSs). A CSS
contains CONET nodes and exploits an under-CONET technology to
transfer data among CONET nodes. A CSS could be: i) a couple of
nodes interconnected by a point-to-point link, e.g. a PPP link or a
UDP/IP overlay link; ii) a layer-2 network, e.g. Ethernet; iii) a
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layer-3 network, e.g. a private/public IPv4 or IPv6 network, or a
whole IP Autonomous System, or even the whole current Internet.
2. ICN information header
In this section we present the information header that contains the
ICN related information. In the first variant of our solution, this
information will be carried in the IP options, while in the second
variant it will be included at the beginning of the IP payload.
The ICN information header has the following format and content:
+--------+--------+--------+--------+
|pppLLSCr| DS&T | ICN-ID |
+--------+--------+--------+--------+
| optional ICN-ID continuation |
| (variable length) ... |
+--------+--------+--------+--------+
|CSN(opt)|optional CSN cont. ... |
+--------+--------+--------+--------+
| optional extensions (TLV fields) |
+--------+--------+--------+--------+
Figure 2: ICN information
ppp : CONET Information Unit Type - This three bits field is used to
differentiate between different types of CONET Information Units
(CIUs)
0 Reserved
1 Interest CONET Information Unit (Interest CIU)
2 Named-data CONET Information Unit (Named-data CIU)
3-7 Reserved
LL : ICN-ID Length Specification - This two bits field provides the
length of ICN Identifier (ICN-ID) field or specifies how the ICN-ID
length is provided.
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0 16 bytes length
1 Reserved
2 ICN-ID field starts with a one byte length field
(ICN-ID length in bytes)
3 Reserved
S : Sequence number indication - This one bit field tells if a chunk
Sequence Number fiels is present in the Option after the ICN-ID field
0 No Chunk Sequence Number field is present
1 Chunk Sequence Number field is present after the ICN-ID field
C : cache indication - This one bit field is used to control cache
operations.
0 No cache
1 Cache
Within Information Units that request for content (e.g. interest
CIU), if the bit is set to "No cache" it indicates to the crossed
nodes not to look for the content in the cache, but to forward the
request toward the source. Within Information Units that carry
content (e.g. named-data CIU), if the bit is set to "No cache" it
indicates to the crossed nodes not to cache the content.
r : reserved - This one bit field in the first byte after the option
length is reserved.
DS&T : Diffserv and Type - This one byte field is used to
differentiate quality of services that can be provided by the network
to the delivered content and to identify the content type. This
field can be used to encode the content type and the priority as
follows:
+--------+
|Fxxxxxxx|
+--------+
+--------+
|0TTTTPPP|
+--------+
+--------+
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|1TTTTTTT|
+--------+
The righmost bit can be considere as a flag F. If the flag bit F is
set to 0 the three rightmost bits encode 8 priority levels and other
4 bits are for the content-type. If the flag bit is set to one, no
preallocated semantic to the remaining bits is given.
ICN-ID : ICN Identifier (ICN-ID) field - The ICN-ID is a unique
identifier for the content. The ICN-ID is carried in the ICN-ID
field. How to determine the length of this field is defined by the
ICN-ID Length Specification field. If the ICN-ID Length
Specification field determines the field length, the ICN-ID field
only carries the ICN-ID. If the ICN-ID Length Specification field
indicates that the field length is carried in the field itself, the
ICN-ID field starts with a one byte field that determines its length.
If ICN-ID Length Specification = 0 (i.e. 16 bytes len),
the ICN-ID field is as follows:
+--------+--------+--------+--------+
| ICN-ID |
+--------+--------+--------+--------+
| |
+--------+--------+--------+--------+
| |
+--------+--------+--------+--------+
| |
+--------+--------+--------+--------+
If ICN-ID Length Specification = 2 (i.e. ICN-ID starts with a one
byte length field), the ICN-ID field is as follows:
+--------+--------+--------+--------+
| length | ICN-ID |
+--------+--------+--------+--------+
| ... |
+--------+--------+--------+--------+
| ... |
The ICN-ID starts with a two bytes field called ICN-ID namespace ID
that determines the structure of the rest of the ICN-ID. ICN-ID
namespace values needs to be assigned by the IANA. Note that in most
circumstances, the ICN-ID can be processed by the routers as an
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opaque object, as described in Section 4. This is why the ICN-ID
namespace ID has been included at the beginning of the ICN-ID itself.
In other cases the nodes are requested to perform a forward-by-name
procedure, which may require a semantic understanding of the ICN-ID.
+--------+--------+--------+--------+
| ICN-ID namesp ID| ... |
+--------+--------+--------+--------+
| ... |
+--------+--------+--------+--------+
| ... |
+--------+--------+--------+--------+
| ... |
+--------+--------+--------+--------+
CSN : Chunk Sequence Number - This optional field carries the Chunk
Sequence Number that identifies a portion of the content. When a
content is split in a sequence of smaller unit called "chunks", this
field can explitly carry the sequence number of the chunk (another
solution is obvioulsy to embed the chunk number in the ICN-ID). The
Chunk Sequence Number is represented with a variable number of bytes.
An initial bit pattern determines the length of the CSN field.
1 byte CSN (7 bits CSN range)
+--------+
|0 |
+--------+
2 bytes CSN (14 bit CSN range)
+--------+--------+
|10 |
+--------+--------+
3 bytes CSN (21 bit CSN range)
+--------+--------+--------+
|110 | | |
+--------+--------+--------+
4 bytes CSN (28 bit CSN range)
+--------+--------+--------+--------+
|1110 | | | |
+--------+--------+--------+--------+
5 bytes CSN (32 bit CSN range)
+--------+--------+--------+--------+
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|11110000| | | |
+--------+--------+--------+--------+
| |
+--------+
6 bytes CSN (40 bit CSN range)
+--------+--------+--------+--------+
|11110001| | | |
+--------+--------+--------+--------+
| | |
+--------+--------+
Binary patterns from 11110010 to 11111111 are reserved. They can be
used to extend the CSN range if needed. With the above defined
option, we can have up to 2^40 chunks in a content. Assuming a
relatively small chunk size of 1 KBytes, it is possible to have a
content of 1099 TeraBytes, while assuming a more reasonable chunk
size of 256 Kbyte it is possible to have a content of 281474
TeraBytes (218 PetaBytes).
The rationale for having a variable length encoding is the following.
The CSN range for a given content is determined by the content size
divided by the chunk size. As content of very different sizes can be
transmitted, the CSN range can be very different. Therefore it is
not efficient to dimension this field considering the maximum number
of chunks in which a content can be split.
3. CONET protocol
A specific IP protocol number needs to be assigned to the CONET
protocol:
CONET IP protocol number : xxx (to be assigned by IANA).
The figure below shows the CONET protocol stack. CONET protocol is
divided in two sub-layers, whose data unit are respectively denoted
as "Carrier Packets" and "CONET Information Units". A CONET
Information Unit (CIU) can be split into different Carrier Packets.
Each Carrier Packet is transported by an IP packet. There are
different types of CONET Information Units, the CIU type information
is carried in the CONET Information Unit Type field in the CONET IP
option.
+--------+--------+--------+ \
| CONET Information Units | |
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+--------+--------+--------+ |
|
+--------+--------+--------+ |- CONET protocol
| Carrier Packets | |
+--------+--------+--------+ |
|
+--------+--------+--------+ /
| IP (opt. CONET IP option)|
+--------+--------+--------+
Figure 3: CONET protocol layers
The generic structure of a Carrier Packet (CP) is reported hereafter:
+-------------------------+
| CP Payload header |
+-------------------------+
| CP Payload |
+-------------------------+
| CP Path state |
+-------------------------+
The ICN information described in the previous section can be
transported either in the IP Option or at the beginning of the CP
Payload header. The CP Payload header includes specific information
for each CIU type and can depend on the "transport" protocol. It
will be described in other specification documents. The definition
of a receiver driven ICN transport protocol called ICTP (Information
Centric Transport Protocol) is proposed in [I-D.ICTP] (see also
[ICTP12]). The CP payload header contains the length of the CP
Payload and allows to identify the start of the CP Path state field.
The CP Path state field can be used in End-Nodes, Border Nodes and
Serving Nodes to assist in the forwarding operation of carrier
packet, therefore it is described here.
The CP Path State field stores the End-Node address and the addresses
of the set of crossed Border Nodes in the path from End-Node to the
Serving Node (or to a border or Intermediate Node that provides a
requested content). The format of the CP path state field is
reported hereafter (assuming that IPv4 addresses are carried). The
use of CP Path state is optional, as the path from End-Node to
Serving Node can be stored in the so called PIT (Pending Interest
Table) in the crossed nodes [Jacobson09]. A node crossed by an
Interest packet can either add its address to the CP Path State (and
create the CP Path State field if not present) or store the pending
interest in the PIT.
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CP Path State field
+--------+--------+--------+--------+
|0 len | pointer| ad-type| addr 1 |
+--------+--------+--------+--------+
| addr 2 | addr 3 | addr 4 | ad-type|
+--------+--------+--------+--------+
| addr 1 | addr 2 | addr 3 | addr 4 |
+--------+--------+--------+--------+
| ... |
+--------+--------+--------+--------+
+--------+--------+--------+--------+
|1 len | pointer |
+--------+--------+--------+--------+
| ad-type| addr 1 | addr 2 | addr 3 |
+--------+--------+--------+--------+
| addr 4 | ad-type| addr 1 | addr 2 |
+--------+--------+--------+--------+
| addr 3 | addr 4 |
+--------+--------+
The length field specifies the length of the CP Path State field in
bytes. If the first bit of the len field is 0, the remaining 7 bits
of the first byte are used as len field and both the length field and
the pointer field are one byte length. In this case the maximum
value of the length of the CP Path State field is 127. If the first
bit of the len field is 1, both the length field and the pointer
field are two bytes length. In this case the maximum value of the
length of the CP Path State field is 32767.
The pointer field specifies the offset, starting from the start of
the CP Path State field where the last address has been inserted.
Each address is represented as a couple (ad-type, address) it could
be represented by a triple (ad-type, ad-length, address) if the
address type is of variable length. The ad-type field is one byte
size and currently admitted values are:
0 Reserved
1 Public IPv4 address (len is 4 bytes, no ad-length needed)
2 Public Ipv6 address (len is 16 bytes, no ad-length needed))
3 Ethernet address (len is 6 bytes, no ad-length needed))
4-255 Reserved
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4. Procedures
4.1. Interest CONET Information Unit (Interest CIU)
4.1.1. Processing in the End-Node
An end-node that wants to retrieve a content (or better a Chunk of a
content) issues an Interest CIU, the ICN-ID and the Chunk Sequence
Number of the required Content are respectively transported in the
ICN Identifier (ICN-ID) field and in the CSN field of the ICN
information header. The end-node stores its IP address in CP path
state field, initializing the pointer field. Assuming for simplicity
that the Interest CIU will fit into a single Carrier Packet, the
Interest CIU will be included in the Carrier Packet that in turn is
inserted into an IP packet.
The end-node must now determine the destination IP address for the
Carrier Packet. The end-node performs a forward-by-name operation,
trying to associate the ICN-ID with a next hop (i.e. with the IP
address of the next hop). The next hop can be the Serving Node (if
the Serving Node is in the same CONET Sub System of the end-node) or
a Border Node of the CONET Sub System (if the Serving Node is in a
different CONET Sub System). Typically the End-Node does not
participate to the content routing protocols, therefore it cannot
resolve the ICN-ID into the address of the next hop, but it has to
ask an external entity, behaving in a similar way of a current name
server (such external entity could be a part of a system that handles
the content routing, called Routing Name System). Once this
information is retrieved, the end-note can fill the IP destination
address in the IP header and sends the packet. The end-node may
cache the mapping (ICN-ID -> next hop) into its memory as well.
4.1.2. Processing in the Serving Node
If the Serving Node is in the same CONET than the end-node, the
Serving Node IP address will be used a destination IP address by the
end-node. The Serving Node will receive an IP packet directed to
itself, whose IP protocol number is "CONET". Therefore the packet
will be internally dispatched toward the "CONET entity" in the
Serving Node. The CONET entity reads the CONET information unit type
from the CONET IP options and recognizes that the received packet is
an interest packet. Then it reads the ICN-ID and Chunk Sequence
Number in the ICN information header, the ICN-ID will correspond to a
content provided by the Serving Node. The CONET entity will then
process the CONET transport protocol information carried in the IP
payload, which may for example specify a requested offset within the
chunk. Finally the CONET entity will respond to the interest packet
by sending the requested named-data CIU.
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4.1.3. Processing in the Border Node
If the Serving Node is in a different CONET Sub System than the end-
node, the address of a CONET Border Node will be used a destination
IP address by the end-node. The Border Node will receive an IP
packet directed to itself, whose IP protocol number is "CONET".
Therefore the packet will be internally dispatched toward the "CONET
entity" in the Border Node. The CONET entity reads the CONET
information unit type from the ICN information header and recognizes
that the received packet is an interest packet. Then it reads the
ICN-ID and Chunk Sequence Number in the ICN information header and is
able to understand which content and which part of the available
content it needs to provide. If the Cache indication field is set to
"No Cache" or if the field is set to "Cache" but the chunk is not
available in the cache, the Border Node starts the forward-by-name
process. It will resolve the next hop of the interest packet, which
can be a Serving Node in a different CONET Sub System (with respect
to the one from which the interest packet was received) connected to
the Border Node, or another Border Node in the path toward the
Serving Node. Before sending out the packet, the Border Node adds
its IP address in the CP Path State field and updates the pointer
field. Note that these procedures needs to be performed in the "fast
path" of the Border Node (in this case the CONET entity in the Border
Node can be seen as an integral part of the enhanced IP protocol).
If the Cache indication field is set to "Cache" and the Border Node
has found that the chunk corresponding to the ICN-ID/CSN is available
in its cache, the Border Node will process the CONET transport
protocol information carried in the IP payload, which may for example
specify a requested offset within the chunk and it will respond to
the interest packet by sending the requested named-data CIU.
4.1.4. Processing in the Intermediate Node
When a packet is sent to the CONET next hop (as selected by the End-
Node or by a Border Node) using the IP destination address of the
next hop resolved by the forward-by-name, it can cross different IP
routers in the path from the sending node and the next hop. A
crossed router that is aware of the ICN information header, is a
CONET Intermediate Node. This node may have cached the the chunk
that is requested by the interest packet. The Intermediate Node
works as follows. When processing the IP header for the received
packet, it finds that the packet contains the CONET IP protocol. If
the Cache indication field is set to "No Cache", the Intermediate
Node forwards the packet using the destination IP address. If the
Cache indication field is set to "Cache", the Intermediate Node
checks the presence of the chunk in its cache before forwarding the
IP packet. Therefore, it reads the ICN-ID and Chunk Sequence Number
in the ICN information header and checks if the chunk is present in
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its cache. If the chunk is not present, the normal IP processing is
continued. Note that these operations needs to be performed in the
"fast path" of the router and they only require information that is
transported in the IP option. If the chunk is present in the CONET
router cache, the router will process the CONET transport protocol
information carried in the IP payload, which may for example specify
a requested offset within the chunk and it will respond to the
interest packet by sending the requested named-data CIU.
4.1.5. Processing in the legacy routers
When a packet is sent to the CONET next hop (as selected by the End-
Node or by a Border Node) using the IP destination address of the
next hop resolved by the forward-by-name, it can cross different IP
routers in the path from the sending node and the next hop. If a
crossed router is a legacy router not aware of the CONET protocol, it
will simply forward the packet looking at the IP destination address.
If the ICN information header is carried in the IP Option, a
requirement for such legacy router is to be configured not to drop IP
packets carrying unidentified IP options.
4.2. Named data CONET Information Unit (Named data CIU)
4.2.1. Processing in the responding node
The responding node is the node that is able to provide a content
(identified by ICN-ID and Chunk Sequence Number) to a requesting end-
node. Therefore the responding node can be a Serving Node which
provides an original copy of the content, or a Border Node /
Intermediate Node that provide a cached copy of the content. The
responding node will use the Path State information contained in the
received carrier packet carrying the Interest CIU to forward back the
carrier packets containing the named-data CIU towards the requesting
end-node. In particular, it will use the pointer field to read the
last address in the list and will use it as IP destination address
for the Carrier packet carrying the named-data CIU. We can denote
this address as "CONET previous hop". Then it will update the
pointer field so that the next node will use the previous address in
the list. It may choose to strip the used address from the list in
the CP Path state, thereby reducing the CP Path State field length.
4.2.2. Processing in a Border Node
The Border Node will receive an IP packet directed to itself, whose
IP protocol number is "CONET". Therefore the packet will be
internally dispatched toward the "CONET entity" in the Border Node.
The CONET entity reads the CONET information unit type from the ICN
information header and recognizes that the received packet is a
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named-data packet. Again, we stress that this processing should be
performed in the fast path. Being a named-data packet, the Border
Node will read the CP Path State field in the Carrier Packet and by
using the pointer field will identify the CONET previous hop in the
path towards the requesting end-node. Before sending out the packet,
it will update the pointer field in the CP Path State field. The
destination IP address of the packet will be set to the CONET
previous hop retrieved from the CP Path State field. If the Cache
indication bit in the IP option is set to "Cache", the Border Node
may choose to cache the CIU that is transported by the carried
packet. In this case, it is reccomended that the Border Node
dispatches the packet as soon as possible and operates on a local
copy to perform cache related operations.
4.2.3. Processing in an Intermediate Node
An Intermediate Node, i.e. a router in the path between a Serving
Node or a Border Node and the CONET previous hop, which is aware of
the CONET option, may decide to cache the named data CIU transported
by a carrier packet. The Intermediate Node will receive an IP packet
with an IP destination equal to the CONET previous hop and will
immediately forward this packet using IP routing. Then, if the Cache
indication bit in the IP option is set to "Cache", the Intermediate
Node may choose to cache the CIU that is transported by the carried
packet.
4.2.4. Processing in the legacy routers
When a packet is sent to the CONET previous hop (as selected by the
Serving Node or by a Border Node) using the IP destination address of
the previous hop obtained using the CP Path State information, it can
cross different IP routers in the path from the sending node and the
previous hop. If a crossed router is a legacy router not aware of
the CONET IP protocol, it will simply forward the packet looking at
the IP destination address. If the ICN information header is carried
in the IP Option, a requirement for such legacy router is to be
configured not to drop IP packets carrying unidentified IP options.
5. Forward-by-name framework
The forward-by-name process is performed in the end-node and in
Border Nodes in order to resolve a ICN-ID into the next hop towards a
Serving Node for the given ICN-ID. This document provides a
framework under which the forward-by-name procedures can be
performed, and assures that different forward-by-name procedures and
approaches may coexist. These different approaches needs to be
separately specified. The format and the semantic of the ICN-ID may
need to be specified when defining a specific forward-by-name
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approach. This is made possible by the concept of ICN-ID name space
ID, which is carried within the ICN-ID.
The basic procedure that a forward-by-name framework needs to offer
is called resolveICN-ID, it takes as input the ICN-ID and returns the
next_hop_address. This procedure is performed by end-nodes and by
Border Nodes that are not able to provide a cached response for a
content requested by an End-Node.
resolveICN-ID (ICN-ID) -> next_hop_address
The tables on which the forward-by-name procedures are based are
populated by Serving Nodes and by Border Nodes. The procedure is
initiated by Serving Nodes that advertize the hosted content with the
advertizeICN-ID procedure. In turn, the procedure is replicated by
the Border Nodes that spread the received advertising toward other
Border Nodes. This procedure takes as input a ICN-ID, the address of
the node performing the procedure, and the path information towards
the Serving Node as seen by the node performing the procedure.
Depending on the specific content routing approach, the path
information can be simply an hop count, or it could be the path list
(as in the BGP AS-PATH).
advertizeICN-ID (ICN-ID, node_address, path_info)
In the following section we define two CONET default name spaces. It
could be more appropriate that in future version of this document
this specification is provided in a separate document.
6. CONET default namespaces
We define two default ICN-ID name spaces for CONET, one is based on
variable length strings as ICN-ID, as it was proposed in
[Jacobson09], the second one is based on fixed length hashes. The
two namespaces are assigned the following ICN-ID name space IDs.
+----------------------------------------------------------------+
| Namespace ID | |
+----------------------------------------------------------------+
| 1 | VLL (Variable Length Label) ICN-ID namespace |
+----------------------------------------------------------------+
| 2 | PLHB (Principal/Label Hash Based) ICN-ID namesp.|
+----------------------------------------------------------------+
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In the VLL (Variable Length Label) CONET namespace the ICN-ID is
simply the string representation of a resource. As described in
[Jacobson09] ICN-IDs are hierarchically structured so that an
individual name is composed of a number of components (see
[Jacobson09] for further details. An authority is needed to ensure
the uniqueness of the ICN-IDs. The approach should be similar on how
the uniqueness of DNS names is granted in today's Internet.
In the Principal/Label Hash Based CONET namespace the ICN-ID is the
composition of two hash values, as follows:
ICN-ID = ( hash (Principal) , hash (Label) )
In the Principal/Label Hash Based CONET namespace the Hash(principal)
is a 8 bytes hash of a string representing the Principal. The Label
is a 6 bytes hash of a string representing the label. A central
authority is needed to ensure the uniqueness of the Hash(principal),
i.e. a Principal cannot be assigned if its hash collides with an
already assigned hash. The Principal is responsible to ensuring that
each Hash(Label) belonging to the Principal are unique. Therefore a
Label cannot be used by a Principal if its hash collides with the
Hash of an already used Label.
7. Two ways of carrying ICN information in IP packets
Two ways of carrying the ICN information in IP packets have been
considered. The first way introduces new IP Options to be included
in IPv4 and IPv6 headers, the second option simply includes the ICN
information header at the beginning of the CP payload header, that is
within the IP payload. Hereafter, the details related to the
definition and use of the IP Options are given, then the two ways are
compared.
7.1. Using CONET IP Option to carry ICN information
The CONET IPv4 option has the following format:
+--------+--------+--------+--------+
|100xxxxx|yyyyyyyy|pppLLSCr| DS&T |
+--------+--------+--------+--------+
| ICN-ID (variable length) |
| ... |
+--------+--------+--------+--------+
|CSN(opt)|optional CSN cont. ... |
+--------+--------+--------+--------+
| optional extensions (TLV fields) |
+--------+--------+--------+--------+
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Figure 4: CONET IP Option for IPv4
The CONET IPv6 option has the following format:
+--------+--------+--------+--------+
|001xxxxx|yyyyyyyy|pppLLSCr| DS&T |
+--------+--------+--------+--------+
| ICN-ID (variable length) |
| ... |
+--------+--------+--------+--------+
|CSN(opt)|optional CSN cont. ... |
+--------+--------+--------+--------+
| optional extensions (TLV fields) |
+--------+--------+--------+--------+
Figure 5: CONET IP Option for IPv6
For IPv4 the first byte (the option type) is as follows:
Type:
Copied flag: 1 (all fragments must carry the option)
Option class: 0 (control)
Option number: xxxxx (decimal) TO BE ALLOCATED BY IANA
For IPv6 the first byte (the option tyep) is as follows:
Type:
Unrecognized option action : 00
(skip option, process the rest of the header)
Change allowed flag : 0
(option data cannot change while the datagram is en route)
Option number: xxxxx (decimal) TO BE ALLOCATED BY IANA
Length:
yyyyyyyy: variable length of IP option in bytes (including the
Type and Length bytes
7.2. IPv6 handling of CONET option
The IPv6 CONET option has to be interpreted by all routers in the
path that are ICN capable. Therefore we it naturally fits into the
the IPv6 Hop-by-hop header, which is the first extension header that
can be present after the fixed part of the header. The Hop-by-hop
header is meant to be read by all routers in the path.
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7.3. Comparison among the two ways
If the IP Option is used, a CONET ICN packet can be identified by the
presence of the IP option. Otherwise, it has to be identified by
looking at the IP Protocol type information in the IP header.
The first advantage of the solution based on IP options is
conceptual: it allows an ICN Node to take routing decision by
considering the information contained in the layer 3 (IP) header.
Moreover, is a packet gets fragmented at IP level, each fragment
keeps the IP Option in its IP header, allowing the processing of the
single fragments at ICN level. The disadvantages are: legacy IP
nodes could have some problems with unrecognized IP options
(experiencing higher processing times or even dropping such packets);
a more complex implementation in end nodes, as it requires changes in
the IP layer. In [CONET11] we investigated (with practical
experiments on PlanetLab) how our unrecognized IP option is handled
by current routers in the Internet. In the large majority of tests
it was possible to add unrecognized options and achieve end-to-end
CONET connectivity among arbitrary PlanetLab nodes, while in few
cases some routers in the path have dropped the packets. IP Options
have often been criticized because their support in current routers
would impose a performance penalty, but may be we can assume here
that routers will be modified to support Information Centric
Networking so this performance issue may not be critical.
The advantages of the other approach (not using the IP options) are
complementary: the implementation in terminals is simpler and legacy
IP nodes are not affected by the ICN information carried in the IP
payload. A disadvantage of this solution is that when IP packets
gets fragmented, the IP fragments loose the ICN information header.
Strictly speaking, a node operating in this approach is not just a
router, as it is using layer 4 information to process the packets so
it can be seen as a middlebox [RFC3234] capable of performing ICN
routing (and caching) functionality. This disadvantage is not
critical in nodes that are in any case capable of operating with
transport layer information (e.g. a node with an SDN/OpenFlow
architecture [ICN-SDN13]).
8. IANA Considerations
This document requires the allocation of one IP protocol number by
the IANA.
This document requires the allocation of one IP option by the IANA if
the solution of using IP options is adopted
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This document requires that IANA will maintain the registry of CONET
namespaces.
9. Security Considerations
Security considerations to be provided
10. References
10.1. Normative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September
1981.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
10.2. Informative References
[CONET11] A. Detti, et al., ., "CONET: A Content Centric Inter-
Networking Architecture", ACM SIGCOMM Workshop on
Information-Centric Networking (ICN-2011), Toronto, Canada
, August 2011.
[I-D.ICTP]
Salsano, S., Detti, A., Blefari-Melazzi, N., and M.
Cancellieri, "ICTP - Information Centric Transport
Protocol for CONET ICN", draft-salsano-ictp-02 (work in
progress), June 2012.
[ICN-SDN13]
Blefari-Melazzi, N., Detti, A., Morbito, G., Salsano, S.,
and L. Veltri, "Information Centric Networking over SDN
and OpenFlow: Architectural Aspects and Experiments on the
OFELIA Testbed", conditionally accepted (minor revisions)
to Elsevier Computer Networks special issue on
Information-Centric Networking - arXiv preprint
arXiv:1301.5933 , 2013.
[ICTP12] S. Salsano, et al., ., "Transport-layer issues in
Information Centric Networks", ACM SIGCOMM Workshop on
Information-Centric Networking (ICN-2012), Helsinki,
Finland , August 2012.
[Jacobson09]
V. Jacobson, et al., ., "Networking named content", Proc.
of ACM CoNEXT 2009 , 2009.
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[Koponen07]
T. Koponen et al., ., "A data-oriented (and beyond)
network architecture", Proc. of ACM SIGCOMM 2007 , 2007.
[RFC3234] Carpenter, B. and S. Brim, "Middleboxes: Taxonomy and
Issues", RFC 3234, February 2002.
Appendix A. Acknowledgments
We acknowledge the financial support by the EU in the context of the
CONVERGENCE and OFELIA research projects
Appendix B. Document history
draft-detti-conet-ip-option-05
o new title "IP protocol suite extensions to support CONET
Information Centric Networking"
o added the generic ICN information header and a second variant of
the solution not using the IP Option
draft-detti-conet-ip-option-03
o new title "IPv4 and IPv6 Options to support Information Centric
Networking"
o added IPv6 support with IPv6 Option
Authors' Addresses
Andrea Detti
Univ. of Rome "Tor Vergata"
Via del Politecnico, 1
Rome 00133
Italy
Email: andrea.detti@uniroma2.it
Stefano Salsano
Univ. of Rome "Tor Vergata"
Via del Politecnico, 1
Rome 00133
Italy
Email: stefano.salsano@uniroma2.it
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Nicola Blefari-Melazzi
Univ. of Rome "Tor Vergata"
Via del Politecnico, 1
Rome 00133
Italy
Email: blefari@uniroma2.it
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