Network Working Group A. Azimov
Internet-Draft E. Bogomazov
Intended status: Standards Track Qrator Labs
Expires: May 19, 2018 R. Bush
Internet Initiative Japan
K. Patel
Arrcus, Inc.
K. Sriram
US NIST
November 15, 2017
New definition of ISP internal eBGP border using BGP Roles
draft-ymbk-idr-isp-border-02
Abstract
This document proposes a new definition of ISP borders using BGP
Roles. It may be used to improve the BGP best path selection
algorithm for better support of hot-potato routing between different
internal ASNs of an ISP. It may also be used to enable transmission
of local attributes between different internal ASNs of an ISP.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
be interpreted as described in RFC 2119 [RFC2119] only when they
appear in all upper case. They may also appear in lower or mixed
case as English words, without normative meaning.
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 May 19, 2018.
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Copyright Notice
Copyright (c) 2017 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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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Changes in BGP decision process . . . . . . . . . . . . . . . 3
3. Local Attributes Transmission . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Normative References . . . . . . . . . . . . . . . . . . . . 3
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
The BGP best path selection algorithm (Section 9.1.2.2 of [RFC4271])
has a very clear definition of a network border: different ASNs -
different networks. It differs from some real world situations when
two networks become one business entity and want to operate as one
network.
Today BGP does not provide any robust or automated support for such
merging networks:
o There is no support for carrying local attributes through this
border,
o Hot-potato routing, implemented by eBGP being preferred to iBGP,
does not work, and
o Route Leak prevention inside such a united network can not be
easily automated.
In [I-D.ietf-idr-bgp-open-policy] BGP Roles were introduced - a
configuration option that strongly enforces agreement on real-world
peering relations between two BGP speakers. This configuration
option can accept values of: Peering, Customer, Provider and
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Internet-Draft Network border definition November 2017
Internal. These values could be used in a new ISP border definition:
Internal vs. External. With this definition of network borders, it
becomes easy to allow robust propagation of local attributes between
different ASNs of one ISP. It could be also used to improve the hot-
potato routing mechanism: where routes learned from External BGP
connections should be preferred over Internal, even those which cross
the ISP's internal AS/AS boundary.
2. Changes in BGP decision process
To improve hot-potato routing for networks with multiple ASNs we
propose to insert before d) in Section 9.1.2.2 of [RFC4271] next
step:
If at least one of the candidate routes was received via a BGP
session with External (Peer, Provider, Customer) role, remove from
consideration all routes that were received via BGP sessions with an
Internal role.
While this step will improve traffic control for ISPs with multiple
ASNs it will have no affect on ISPs with single ASN.
3. Local Attributes Transmission
Propagation of local attributes through an ISP's internal AS/AS
border could be enabled only if both sides set Internal roles in
their BGP Open negotiation. Different attributes may still have
different transmission policy:
o iOTC attribute from [I-D.ietf-idr-bgp-open-policy] MUST be sent to
enforce route leak prevention,
o LOCAL_PREF attribute MAY be sent, and
o MED attribute MAY be sent without changes.
4. IANA Considerations
This document has no IANA actions.
5. Normative References
[I-D.ietf-idr-bgp-open-policy]
Azimov, A., Bogomazov, E., Bush, R., Patel, K., and K.
Sriram, "Route Leak Prevention using Roles in Update and
Open messages", draft-ietf-idr-bgp-open-policy-01 (work in
progress), July 2017.
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[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>.
Authors' Addresses
Alexander Azimov
Qrator Labs
Email: aa@qrator.net
Eugene Bogomazov
Qrator Labs
Email: eb@qrator.net
Randy Bush
Internet Initiative Japan
Email: randy@psg.com
Keyur Patel
Arrcus, Inc.
Email: keyur@arrcus.com
Kotikalapudi Sriram
US NIST
Email: ksriram@nist.gov
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