Network Working Group A. Detti
Internet-Draft S. Salsano
Intended status: Informational N. Blefari-Melazzi
Expires: November 29, 2012 Univ. of Rome "Tor Vergata"
May 28, 2012
IPv4 and IPv6 Options to support Information Centric Networking
draft-detti-conet-ip-option-03
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 using a new IP Option (both for IPv4
and IPv6). The new IP option is used by routers 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.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 29, 2012.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. CONET IP Option . . . . . . . . . . . . . . . . . . . . . . . 4
3. IPv6 handling of CONET option . . . . . . . . . . . . . . . . 10
4. CONET protocol . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. Interest CONET Information Unit (Interest CIU) . . . . . . 12
5.1.1. Processing in the End-Node . . . . . . . . . . . . . . 12
5.1.2. Processing in the Serving Node . . . . . . . . . . . . 13
5.1.3. Processing in the Border Node . . . . . . . . . . . . 13
5.1.4. Processing in the Intermediate Node . . . . . . . . . 14
5.1.5. Processing in the legacy routers . . . . . . . . . . . 14
5.2. Named data CONET Information Unit (Named data CIU) . . . . 15
5.2.1. Processing in the responding node . . . . . . . . . . 15
5.2.2. Processing in a Border Node . . . . . . . . . . . . . 15
5.2.3. Processing in an Intermediate Node . . . . . . . . . . 15
5.2.4. Processing in the legacy routers . . . . . . . . . . . 16
6. Forward-by-name framework . . . . . . . . . . . . . . . . . . 16
7. CONET default namespaces . . . . . . . . . . . . . . . . . . . 17
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
9. Performance Considerations . . . . . . . . . . . . . . . . . . 18
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
11. Security Considerations . . . . . . . . . . . . . . . . . . . 18
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
12.1. Normative References . . . . . . . . . . . . . . . . . . . 18
12.2. Informative References . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
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1. Introduction
In this memo we propose a new approach to Information Centric
Networking [Koponen07][Jacobson09], 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 proposed solution has
been described in [CONET11].
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.
The 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.
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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
layer-3 network, e.g. a private/public IPv4 or IPv6 network, or a
whole IP Autonomous System, or even the whole current Internet.
In addition to the new CONET IP option, the proposed solution needs a
new Internet Protocol Number to identify the CONET protocol.
2. CONET IP Option
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 2: 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 3: 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
ppp : CONET Information Unit Type - This three bits field is used to
differentiate between different types of CONET Information Units
(CIUs)
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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.
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:
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+--------+
|Fxxxxxxx|
+--------+
+--------+
|0TTTTPPP|
+--------+
+--------+
|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.
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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
opaque object, as described in Section 5. 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
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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)
+--------+--------+--------+--------+
|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.
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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. 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.
4. CONET protocol
In the previous section, we have seen the description of the CONET IP
option that is carried in the header of IP packets. The payload of
IP packets is the CONET protocol and a specific IP protocol number is
assigned to it:
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 | |
+--------+--------+--------+ |
|
+--------+--------+--------+ |- CONET protocol
| Carrier Packets | |
+--------+--------+--------+ |
|
+--------+--------+--------+ /
| IP (with CONET IP option)|
+--------+--------+--------+
Figure 4: CONET protocol layers
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The generic structure of a Carrier Packet (CP) is reported hereafter:
+-------------------------+
| CP Payload header |
+-------------------------+
| CP Payload |
+-------------------------+
| CP Path state |
+-------------------------+
The information contained in the CP Payload header is specific 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 is 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).
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 |
+--------+--------+--------+--------+
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| 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
5. Procedures
5.1. Interest CONET Information Unit (Interest CIU)
5.1.1. 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 CONET IP
option. 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
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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.
5.1.2. 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 CONET IP option, 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.
5.1.3. 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 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 CONET IP option 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
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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.
5.1.4. 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 CONET IP option, 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 option. 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 CONET IP option
and checks if the chunk is present in 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.
5.1.5. 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 IP option,
it will simply forward the packet looking at the IP destination
address. Note that a requirement for such legacy router is to be
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configured not to drop IP packets carrying unidentified IP options.
5.2. Named data CONET Information Unit (Named data CIU)
5.2.1. 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.
5.2.2. 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 CONET
IP options and recognizes that the received packet is a 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.
5.2.3. 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
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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.
5.2.4. 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 option, it will simply forward the packet looking at the
IP destination address. Note that a requirement for such legacy
router is to be configured not to drop IP packets carrying
unidentified IP options.
6. 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
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
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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.
7. 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.|
+----------------------------------------------------------------+
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
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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.
8. Acknowledgments
We acknowledge the financial support by the EU in the context of the
CONVERGENCE research project.
9. Performance Considerations
IP Options have often been criticized because their support in
current routers would impose a performance penalty, but we can assume
here that routers will be modified to support Information Centric
Networking. Compared with "clean slate" approaches where CCN nodes
could be completely different with respect to routers, we believe
that we are able to provide all the functionality we need for
Information Centric Networking, with reasonable modification in
router architectures and preserving all the functionality of current
IP networking.
10. IANA Considerations
This document requires the allocation of one IP option by the IANA.
This document requires the allocation of one IP protocol number by
the IANA.
This document requires that IANA will maintain the registry of CONET
namespaces.
11. Security Considerations
Security considerations to be provided
12. References
12.1. Normative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
September 1981.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
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(IPv6) Specification", RFC 2460, December 1998.
12.2. 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-00 (work in
progress), May 2012.
[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.
[Koponen07]
T. Koponen et al., "A data-oriented (and beyond) network
architecture", Proc. of ACM SIGCOMM 2007 , 2007.
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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