Individual submission H. Uijterwaal
Internet-Draft K. Petrusha
Intended status: Standards Track RIPE NCC
Expires: March 6, 2008 September 3, 2007
RPSL extensions for 32 bit AS Numbers
draft-uijterwaal-rpsl-4byteas-ext-03.txt
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This document specifies extensions to the RPSL language for dealing
with 32 bit (4 byte) AS numbers. It also gives a list of RPSL
attributes that will be affected by this change and that may require
tools to be updated.
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1. Introduction
Four byte (32 bit) AS numbers (ASN32) are defined in [as4bytes].
This document does not specify a format to represent these numbers.
A separate document [asn32rep] proposes to represent them as:
<high order 16 bit value in decimal>.<low order 16 bit value in
decimal>
This format allows users to easily distinguish 16 and 32 bit ASN.
RPSL (Routing Policy Specification Language) ([RFC2622] and
[RFC4012]) uses the format "ASx" for an AS, with x a 1 to 5 digit
number in the range 0 to 65535. RPSL was defined before the
introduction of 32 bit AS numbers (ASN32).
Deployment of ASN32 will start early 2007 [asn32d]. To use these
numbers in RPSL, the RPSL standard will have to be updated to allow
for ASN32. This document defines the necessary extensions to the
RPSL standard.
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 [RFC2119].
2. Proposal
The terms "2-byte only AS Numbers" and "4-byte AS numbers" are
defined in [asn32rep]. Following this document, the field <as-
number> in [RFC2622] (section 2) will be replaced by:
An <as-number> is a string that can be either:
* ASx, for 2-byte only AS numbers, or
* ASy.z for 4-byte AS Numbers, with x and y using the same format
as [asn32rep].
x, y and z are integer numbers in the range 0 to 65535. If y
equals 0, it and the following "." MUST both be dropped. An
application MAY accept a string with y equal to 0 as input.
Similar, following [asn32rep] and [RFC2622], the definition of a
community specification will be replaced by:
An community specification is a string that can be either:
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* x:N, for 2-byte only AS numbers, or
* y.z:N for 4-byte AS Numbers, with x and y using the same format
as [asn32rep].
x, y, z and N are integer numbers in the range 0 to 65535. If y
equals 0, it and the following "." MUST both be dropped. An
application MAY accept a string with y equal to 0 as input.
No other changes to the RPSL standard will be made.
2.1. Background
The proposed format ("ASx.y") for RPSL uses the same format for ASN32
as had been proposed for other representations of ASN32. This will
allow for an easy conversion of data between RPSL-based tools and
other tools.
The format also has the advantage that the number of RPSL attributes
will not change. Proposals based on the RPSL language extension
mechanism will all result in adding a large number of new attributes
to RPSL.
Changing the format of existing attributes has the disadvantage that
the code parsing RPSL data of existing tools will have to be reviewed
and updated to allow for the new format. However, this is something
that has to be done anyway when ASN32 are introduced, as it is a
priori not clear whether code can handle ASN values larger than 2^16.
2.2. Examples
AS3333 refers to the AS with identifier 3333. AS0.3333 refers to the
same AS but this notation should not be used. An identifier of
AS65536 is not valid, even though the identifier can be expressed in
a 32 bit integer. This AS should be referred to as AS1.0.
3. RPSL Attributes affected by this change
The following table lists RPSL attributes that will be affected by
this change. It is intended as a check-list for developpers updating
their tools. In this table:
o A: the AS syntax used in this attribute has changed
o C: the community value syntax used in this attribute has changed
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+--------------+-------------+----+-----------+
| Object-type | Attribute | AS | Community |
+--------------+-------------+----+-----------+
| route: | aggr-bndry | A | |
| | aggr-mtd | A | |
| | components | A | C |
| | inject | A | C |
| | member-of | A | |
| | origin | A | |
| route6: | aggr-bndry | A | |
| | aggr-mtd | A | |
| | components | A | C |
| | inject | A | C |
| | member-of | A | |
| | origin | A | |
| aut-num: | aut-num | A | |
| | default | A | C |
| | export | A | C |
| | import | A | C |
| | mp-default | A | C |
| | mp-export | A | C |
| | mp-import | A | C |
| | member-of | A | |
| as-set: | as-set | A | |
| | members | A | |
| inet-rtr: | local-as | A | |
| | interface | A | C |
| | ifaddr | A | C |
| | peer | A | |
| | mp-peer | A | |
| | member-of | A | |
| filter-set: | filter-set | A | |
| | filter | A | C |
| | mp-filter | A | C |
| rtr-set: | rtr-set | A | |
| | members | A | |
| | mp-members | A | |
| route-set: | route-set | A | |
| | members | A | |
| | mp-members | A | |
| peering-set: | peering-set | A | |
| | mp-peering | A | |
| | peering | A | |
| as-block: | as-block | A | |
+--------------+-------------+----+-----------+
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4. Security Considerations
Many systems will treat strings "xxx.yyy" as real number values and
convert this internally to floating point numbers. One must take
care that this will not happen.
Systems may use unsigned 16-bit integers for the internal
representation of AS numbers. It should be checked that tools
internally use (at least) an unsigned 32-bit number for ASN.
Parsing ASN32 based communities attributes will result in longer byte
strings. It should be checked that tools internally have sufficient
memory allocated to store these strings. One possibility is to use
the extensions to the 8 octet AS Extended Communities [RFC4360]
proposed in A DRAFT THAT HAS EXPIRED BUT WILL BE REVIVED.
5. IANA Considerations
None. (This section may be removed on publication as an RFC.)
6. Acknowledgements
The authors would like to thank James Aldridge, Denis Walker and Rene
Wilhelm for their feedback on this draft.
7. References
7.1. Normative references
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2622] Alaettinoglu, C., Villamizar, C., Gerich, E., Kessens, D.,
Meyer, D., Bates, T., Karrenberg, D., and M. Terpstra,
"Routing Policy Specification Language (RPSL)", RFC 2622,
June 1999.
[RFC4012] Blunk, L., Damas, J., Parent, F., and A. Robachevsky,
"Routing Policy Specification Language next generation
(RPSLng)", RFC 4012, March 2005.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006.
[as4bytes]
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Chen, E. and Q. Vohra, "BGP Support for Four-octet AS
Number Space (draft-ietf-idr-as4bytes, work in
progress).".
[asn32rep]
Michaelson, G., "Canonical representation of 4-byte AS-
numbers (draft-michaelson-4byte-as-representation, work in
progress).".
7.2. Informative references
[asn32d] Huston, G., "4-byte AS Number Policy (RIPE PDP 2005-12).".
Authors' Addresses
Henk Uijterwaal
RIPE NCC
Singel 258
1016 AB Amsterdam
NL
Phone: +31 20 535 4444
Email: henk@ripe.net
Katie Petrusha
RIPE NCC
Singel 258
1016 AB Amsterdam
NL
Phone: +31 20 535 4444
Email: katie@ripe.net
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