Registering New BGP Attribute Types
How to register new attribute types for the Border Gateway Protocol.
Manning, B., "Registering New BGP Attribute Types", RFC 2042, DOI 10.17487/RFC2042, January 1997, <https://www.rfc-editor.org/info/rfc2042>.
@misc{rfc2042,
series = {Request for Comments},
number = 2042,
howpublished = {RFC 2042},
publisher = {RFC Editor},
doi = {10.17487/RFC2042},
url = {https://www.rfc-editor.org/info/rfc2042},
author = {B. Manning},
title = {{Registering New BGP Attribute Types}},
pagetotal = 3,
year = 1997,
month = jan,
} RFC text
Contents
Network Working Group B. Manning
Request for Comments: 2042 ISI
Category: Informational January 1997
Registering New BGP Attribute Types
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Process:
This document describes the process for creating new BGP attribute
type codes. Basic attribute type codes are described in RFC 1771,
pages 12 through 15. These, and new attribute type codes that are
used in the Internet are registered with the IANA.
The actual process will involve the documentation of such attribute
type codes in an RFC. There is no intention of segmenting the code
space into public/private or IP/OSI or any other sectioning.
As each attribute type code is in the process of being developed, it
will use an octet value of 255, which will be reserved for this use.
At the time an attribute type code is assigned a number by the IANA,
the documetnation and code base will be updated to reflect the
authorized attribute type code value.
IANA maintained values will be published in the periodically updated
Assigned Numbers RFC [6]. Requests for assignment of a new attribute
type code should be sent to the IANA (IANA@IANA.ORG) with a subject
that includes the phrase "BGP Attribute Type".
Currently in use attribute type codes are listed below:
Value Code Reference
1 ORIGIN [1]
2 AS_PATH [1]
3 NEXT_HOP [1]
4 MULTI_EXIT_DISC [1]
5 LOCAL_PREF [1]
6 ATOMIC_AGGREGATE [1]
7 AGGREGATOR [1]
8 COMMUNITY [2]
9 ORIGINATOR_ID [3]
10 CLUSTER_LIST [3]
11 DPA [4]
12 ADVERTISER [5]
13 RCID_PATH / CLUSTER_ID [5]
...
255 reserved for development
Security Considerations
Security issues are not discussed in this memo.
References
[1] Rekhter, Y., and Li, T., "A Border Gateway Protocol 4 (BGP-4)",
RFC 1771, March 1995.
[2] Chandra, R., Traina, P., and T. Li, "BGP Communities
Attribute", RFC 1997, August 1996.
[3] Bates, T., Chandra, R, "BGP Route Reflection An alternative
to full mesh IBGP", RFC 1998, June 1996.
[4] Chen, E., Bates, T., "Destination Preference Attribute for BGP",
Work in progress, March 1996.
[5] Haskin, D., "A BGP/IDRP Route Server alternative to a full mesh
routing", RFC 1863, October 1995.
[6] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1700,
ISI, October 1994.
Author's Address
Bill Manning
USC/ISI
4676 Admiralty Way
Marina del Rey, CA. 90292
Phone: 01.310.822.1511
EMail: bmanning@isi.edu
AI ELI5
On this page
§1BGP Attribute Types
BGP (Border Gateway Protocol) uses path attributes to carry routing information along with network prefixes. Each attribute has a numeric type code that identifies what kind of information it contains, such as the origin of a route, the path of autonomous systems it traversed, or the next hop.
As BGP deployments evolved, new attributes were needed for features like route reflection and BGP communities, requiring a formal process for assigning new type codes.
BGP uses numbered tags to label different kinds of routing information attached to routes. This RFC explains how to create new tags.
§2Registration Process
All new BGP attribute types must be documented in an RFC. During development, implementers use the reserved octet value 255 as a placeholder. Once development is complete, the attributes are submitted for registration with IANA (Internet Assigned Numbers Authority).
IANA assigns an official type code number, after which the RFC and the implementation are updated to use the assigned code. Requests should be sent to IANA@IANA.ORG with the subject line including BGP Attribute Type. IANA publishes all assigned values in the periodically updated Assigned Numbers RFC.
To create a new BGP tag, document it in an RFC, then ask IANA for an official number. During testing, you can use 255 as a temporary number.
§3Currently Defined Attributes
At the time of this RFC, thirteen attribute types were in use: ORIGIN (the source of the route), AS_PATH (the autonomous systems traversed), NEXT_HOP (where to send the packet), MULTI_EXIT_DISC (exit preference), LOCAL_PREF (local preference), ATOMIC_AGGREGATE, AGGREGATOR (route aggregation info), COMMUNITY (grouping routes), ORIGINATOR_ID, CLUSTER_LIST (for route reflection), DPA, ADVERTISER, and RCID_PATH.
All defined attribute types and their codes are maintained in the IANA registry and the Assigned Numbers RFC.
BGP uses many standard tags for different kinds of routing information, from which network sent the route to which path it should take.