Internet DRAFT - draft-jaufeerally-bgp-lg-cap
draft-jaufeerally-bgp-lg-cap
Internet Engineering Task Force R. Jaufeerally, Ed.
Internet-Draft TBD
Intended status: Informational July 2021
Expires: 26 January 2022
An in-band BGP mechanism for looking-glass address discovery
draft-jaufeerally-bgp-lg-cap-01
Abstract
Autonomous Systems (ASes) that peer with one another using the Border
Gateway Protocol (BGP) RFC 4271 [RFC4271] do not have an automated
way to tell if the prefixes announced over a particular peering link
are acceped by the peer. One way in which an AS operator can verify
acceptance of routes by a peer is using a looking glass which may be
provided by the peer, however this introduces manual toil in the
operation and turnup of peering links, and does not allow for
continued validation to ensure there are no regressions. Looking
glasses are often manually found by browsing the website of the peer
or via a database of peering participants.
This document proposes a new in-band mechanism for transmitting
administrative data between BGP peers, and defines one such use case
for propagating looking glass addresses. This is done via a new
Address Family Identifier (AFI) which carries a message that we
define here, inside the Multi Protocol (MP_REACH and MP_UNREACH) path
attribute
The looking glass that we expose via the proposed mechanism conforms
to that defined in RFC 8522 [RFC8522].
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 2 January 2022.
Jaufeerally Expires 26 January 2022 [Page 1]
Internet-Draft In-band BGP looking glass capability July 2021
Copyright Notice
Copyright (c) 2021 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 (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Advertising support for the administrative message . . . . . 3
3. Format of the administrative message . . . . . . . . . . . . 3
4. Looking glass payload . . . . . . . . . . . . . . . . . . . . 3
5. Propoagation of looking glass information . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
In this document we introduce a new Address Family Identifier (AFI)
to carry an administrative message via the existing BGP update
message that is defined in RFC 4271 [RFC4271]
When a peer signals support for this AFI, we define a mechanism
through which an administrative message contained within BGP UPDATE
path attributes can be used to propagate inforamation such as but not
limited to a looking glass URL.
1.1. Requirements Language
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 RFC 2119 [RFC2119].
Jaufeerally Expires 26 January 2022 [Page 2]
Internet-Draft In-band BGP looking glass capability July 2021
2. Advertising support for the administrative message
Peers that support sending and receiving administrative messages via
this mechanism MUST advertise support by sending a multiprotocol
capability advertisment, as defined in RFC 4760 section 8 [RFC4760].
The AFI used is that assigned by IANA (Note to editor: insert the
actual value here once assigned).
A peer SHOULD only send the messages defined in this document to a
peer which has advertised support for the administrative message AFI.
3. Format of the administrative message
The administrative message is transmitted through a BGP UPDATE
message containing a multiprotocol reach or multiprotocol unreach
path attribute with the AFI set to the AFI for this document (Note to
editor: insert value here after assignment from IANA). The SAFI
field SHOULD be set to 0 and MUST be ignored by the recipient, as it
is unused in this specification, and is reserved for future use.
The payload format is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| version | type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| payload (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
Figure 1 shows the layout of the administrative message which is to
be contained within the multiprotocol reahable (MP_REACH) and
multiprotocol unreachable (MP_UNREACH) path attributes. Each
submessage type will define its own semantics of when MP_REACH and /
or MP_UNREACH is to be used.
4. Looking glass payload
The looking glass mechanism is disemminated using a administrative
message with a type of 1.
The looking glass mechanism supports advertising to a BGP peer an
HTTP endpoint at which looking glass operations such as but not
limited to: IP prefix lookups in the RIB of the peer, ping,
traceroute, etc. This endpoint, in version 1 of the looking glass
protocol, MUST conform to the standard set out in RFC 8522 [RFC8522].
Jaufeerally Expires 26 January 2022 [Page 3]
Internet-Draft In-band BGP looking glass capability July 2021
The looking glass address can be specified in one of two ways: (1) on
the BGP peer interface itself (i.e. the looking glass can be reached
on the address of the BGP peer router itself), (2) on a URL specified
within the message itself.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| version | ASN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | URL (variable length)... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Looking glass message format
Figure 2 shows the wire format of the administrative message. The
first byte is the looking glass administrative payload version number
which MUST be set to 1. This may be updated in future revisions to
define new functionality, so software MUST ignore paylaods with
unrecognized version numbers. ASN MUST be set to the autonomous
system number of the network that is operating the looking glass.
That is to say, if an AS is announcing its own looking glass this
should be the ASN which is announced in the BGP OPEN message. On the
other hand, if this is a looking glass address propagated from
another peer, this MUST be the ASN of the network originating the
looking glass message. See Section 5 for details on how propagation
is handled.
The URL section is a variable length field which contains the ASCII
encoded HTTP(s) endpoint of the looking glass.
5. Propoagation of looking glass information
While it is useful to have a looking glass to test the connectivity
and route acceptance of a direct peer, it is oftentimes desirable to
know if an "upstream" peer has accepted the route as well. Consider
the case of a tier-2 ISP which has several uplinks to tier-1 ISPs.
In this case, the customer of a tier-2 ISP would benefit to know
whether their routes have been accepted by the tier-1 upstream peers,
which may have different filtering policies, and thus have a
different set of accepted routes.
In the base case to advertise the looking glass of the ASN that is
running the BGP speaker, the speaker sets the ASN field to the ASN of
the speaker itself.
Jaufeerally Expires 26 January 2022 [Page 4]
Internet-Draft In-band BGP looking glass capability July 2021
A BGP speaker SHOULD forward looking glass addresses of a peer P_a to
a peer P_b when a route from P_b has been announced to P_a. This
MUST only be done if P_a has advertised the looking glass address to
the BGP speaker making this decision, and the forwarded URL MUST be
the one which P_a has advertised.
6. Acknowledgements
The authors would like to thank the members of the GROW WG for their
feedback on this draft. (Note to the editor: update this in future
revisions of the draft).
7. IANA Considerations
We request IANA to allocate a new address family identifier for the
administrative message, (Note to editor: fill in here after getting
an assignment)
We also require a registry of types that can be contained within the
administrative message type. This document allocates the first
administrative message type of 1 to be used for the looking glass
message. (Note to editor: add more details here.)
8. Security Considerations
This draft proposes a mechanism for providing more easily automatable
access to a looking glass interface operated by a network. The scope
of the dissemination of these looking glass adresses is to direct
peers which are presumed to have an interest in querying the network
reachability information, for example as part of debugging.
Many network operators already provide looking glass services to the
general public, however these are usually not standardized in their
interfaces, and moreover, are not discoverable in an automated way
which makes scalability difficult, and thus this draft
programatically propagates that information.
Operators MUST treat connections to the looking glass as untrusted.
Operators SHOULD perform apppropriate rate-limiting and MAY deny
abusive clients as per their own policy
Operators may operate the looking glass with an IP access control
list in cases where access is intended only for the peer, however
this is discouraged as running a public facing looking glass brings
the benefit that anyone can use it to debug network issues.
9. References
Jaufeerally Expires 26 January 2022 [Page 5]
Internet-Draft In-band BGP looking glass capability July 2021
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC8522] Stubbig, M., "Looking Glass Command Set", RFC 8522,
DOI 10.17487/RFC8522, February 2019,
<https://www.rfc-editor.org/info/rfc8522>.
9.2. Informative References
Author's Address
Rayhaan Jaufeerally (editor)
TBD
CH- Zurich
Switzerland
Email: ietf@rayhaan.ch
Jaufeerally Expires 26 January 2022 [Page 6]
