Internet-Draft Marking Announcements to BGP Collectors February 2022
Bush & Aben Expires 21 August 2022 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-ymbk-grow-bgp-collector-communities-02
Obsoletes:
4384 (if approved)
Published:
Intended Status:
Best Current Practice
Expires:
Authors:
R. Bush
Internet Initiative Japan
E.M.J. Aben
RIPE NCC

Marking Announcements to BGP Collectors

Abstract

When BGP route collectors such as RIPE RIS and Route Views are used by operators and researchers, currently one can not tell if the collection of paths announced to a collector represents the ISP's customer cone, includes internal routes, includes paths learned from peerings or transits. This greatly reduces the utility of the collected data. This document specifies the use of BGP communities to differentiate the kinds of views being presented to the collectors.

Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

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 https://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 21 August 2022.

Table of Contents

1. Introduction

BGP route collectors such as RIPE RIS [ris] and Route Views [rviews] are used by both operators and researchers. Unfortunately, one can not tell paths announced to a collector are solely from the ISP's customer cone (one's own prefixes and the closure of those to whom transit is provided; i.e. what one would announce to a peer), include internal routes (e.g. inter-router links), or external paths learned via peering or transit. This greatly reduces the utility of the collected data, and has been a cause of much pain over the years. This document suggests the use of BGP communities to differentiate between these categories.

In 2006, [RFC4384] attempted a similar goal but failed to gain traction in the operational community. We believe this was due to its unnecessary complexity. This document proposes two much simpler marking schemes and, if published, will obsolete [RFC4384].

2. Rationale

When an operator uses a collector to look at an ISP's announcement of a prefix, it is very useful to know if the ISP also announced it to their customers and/or peers/transits. Researchers want to differentiate similarly in order to understand expected route propagation.

One usually wishes to ignore any internal-only routes, e.g. inter-router point-to-point links, an ISP may announce to the collector, as they would not be announcing them to peers, transits, or customers. I.e. they would not be used operationally.

An ISP is expected to announce customer routes to their customers, and announce customer routes to their external peers and transits.

In general, one does not need to differentiate whether the ISP will announce to peers or transits; and the ISP may not wish to expose the business relationships with external providers. So this document do not propose to differentiate peers from transit providers.

3. Categories

We consider only three categories of announcements:

Customer Cone:
One's own prefixes and the closure of those to whom transit is provided including routes announced by BGP customers, static prefixes used for non-BGP customers, datacenter routes, etc.
External Routes:
Routes learned from peers and transit providers which the ISP would normally announce to customers but not to peers. Often, ISPs do not announce such routes to collectors. But, as there is no general practice, this category is important to mark.
Internal Routes:
ISPs occasionally announce to the collector Internal point to point and other routes they would not normally announce to customers, peers, or transit providers.

4. Signaling

BGP announcements to route collectors SHOULD be marked with communities indicating into which category the announcement falls. As most collector peers already use community markings similar to these, but ad hoc, the additional effort should be trivial.

The ASN in the marking SHOULD be that of the collector peer. The communities were selected from community values which were unused at the time of this document and SHOULD be as follows:

ASs which do not peer with collectors MAY also choose to use these markings.

Table 1
Category Community
Customer Cone ASN:64994
External Route ASN:64995
Internal Route ASN:64996

Community Markings

5. Alternative Signaling

Alternatively, should marking at the path granularity be considered too revealing, the collector peer could announce a single well-known prefix, for example 10.10.10.10/10, with one or more of the community markings as above, describing the set of paths being announced to the collector.

6. IANA Considerations

As the number of categories is intentionally minimal, an IANA registry should not be needed.

7. References

7.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[ris]
"RIPE Routing Information Service (RIS)", <https://www.ripe.net/analyse/internet-measurements/routing-information-service-ris/routing-information-service-ris>.
[rviews]
"University of Oregon Route Views Project", <http://www.routeviews.org/>.

7.2. Informative References

[RFC4384]
Meyer, D., "BGP Communities for Data Collection", BCP 114, RFC 4384, DOI 10.17487/RFC4384, , <https://www.rfc-editor.org/info/rfc4384>.

Authors' Addresses

Randy Bush
Internet Initiative Japan
5147 Crystal Springs
Bainbridge Island, Washington 98110
United States of America
Emile Aben
RIPE NCC
Singel 258
1016 AB Amsterdam
Netherlands