draft-ietf-idr-aigp-14.txt   draft-ietf-idr-aigp-15.txt 
Network Working Group Pradosh Mohapatra Network Working Group Pradosh Mohapatra
Internet Draft Cumulus Networks Internet Draft Cumulus Networks
Intended Status: Proposed Standard Intended Status: Proposed Standard
Expires: June 16, 2014 Rex Fernando Expires: July 31, 2014 Rex Fernando
Eric C. Rosen Eric C. Rosen
Cisco Systems, Inc. Cisco Systems, Inc.
James Uttaro James Uttaro
ATT ATT
December 16, 2013 January 31, 2014
The Accumulated IGP Metric Attribute for BGP The Accumulated IGP Metric Attribute for BGP
draft-ietf-idr-aigp-14.txt draft-ietf-idr-aigp-15.txt
Abstract Abstract
Routing protocols that have been designed to run within a single Routing protocols that have been designed to run within a single
administrative domain ("IGPs") generally do so by assigning a metric administrative domain ("IGPs") generally do so by assigning a metric
to each link, and then choosing as the installed path between two to each link, and then choosing as the installed path between two
nodes the path for which the total distance (sum of the metric of nodes the path for which the total distance (sum of the metric of
each link along the path) is minimized. BGP, designed to provide each link along the path) is minimized. BGP, designed to provide
routing over a large number of independent administrative domains routing over a large number of independent administrative domains
("autonomous systems"), does not make its path selection decisions ("autonomous systems"), does not make its path selection decisions
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Copyright and License Notice Copyright and License Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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3.4 Creating and Modifying the AIGP Attribute ............. 7 3.4 Creating and Modifying the AIGP Attribute ............. 7
3.4.1 Originating the AIGP Attribute ........................ 7 3.4.1 Originating the AIGP Attribute ........................ 7
3.4.2 Modifications by the Originator ....................... 9 3.4.2 Modifications by the Originator ....................... 9
3.4.3 Modifications by a Non-Originator ..................... 9 3.4.3 Modifications by a Non-Originator ..................... 9
4 Decision Process ...................................... 11 4 Decision Process ...................................... 11
4.1 When a Route has an AIGP Attribute .................... 11 4.1 When a Route has an AIGP Attribute .................... 11
4.2 When the Route to the Next Hop has an AIGP attribute .. 12 4.2 When the Route to the Next Hop has an AIGP attribute .. 12
5 Deployment Considerations ............................. 13 5 Deployment Considerations ............................. 13
6 IANA Considerations ................................... 13 6 IANA Considerations ................................... 13
7 Security Considerations ............................... 13 7 Security Considerations ............................... 13
8 Acknowledgments ....................................... 13 8 Acknowledgments ....................................... 14
9 Authors' Addresses .................................... 14 9 Authors' Addresses .................................... 14
10 Normative References .................................. 14 10 Normative References .................................. 15
11 Informative References ................................ 14 11 Informative References ................................ 15
1. Specification of requirements 1. Specification of requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Introduction 2. Introduction
There are many routing protocols that have been designed to run There are many routing protocols that have been designed to run
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3.4.1. Originating the AIGP Attribute 3.4.1. Originating the AIGP Attribute
An implementation that supports the AIGP attribute MUST support a An implementation that supports the AIGP attribute MUST support a
configuration item, AIGP_ORIGINATE, that enables or disables its configuration item, AIGP_ORIGINATE, that enables or disables its
creation and attachment to routes. The default value of creation and attachment to routes. The default value of
AIGP_ORIGINATE MUST be "disabled". AIGP_ORIGINATE MUST be "disabled".
A BGP speaker MUST NOT add the AIGP attribute to any route whose path A BGP speaker MUST NOT add the AIGP attribute to any route whose path
leads outside the "AIGP administrative domain" to which the BGP leads outside the "AIGP administrative domain" to which the BGP
speaker belongs. It may be added only to routes that satisfy one of speaker belongs. When the AIGP attribute is used, changes in IGP
routing will directly impact BGP routing. Attaching the AIGP
attribute to "customer routes", "Internet routes", or other routes
whose paths lead outside the infrastructure of a particular AIGP
administrative domain, could result in BGP scaling and/or thrashing
problems.
The AIGP attribute may be added only to routes that satisfy one of
the following conditions: the following conditions:
- The route is a static route that is being redistributed into BGP; - The route is a static route, not leading outside the AIGP
administrative domain, that is being redistributed into BGP;
- The route is an IGP route that is being redistributed into BGP; - The route is an IGP route that is being redistributed into BGP;
- The route is an IBGP-learned route whose AS_PATH attribute is - The route is an IBGP-learned route whose AS_PATH attribute is
empty; empty;
- The route is an EBGP-learned route whose AS_PATH contains only - The route is an EBGP-learned route whose AS_PATH contains only
ASes that are in the same AIGP Administrative Domain as the BGP ASes that are in the same AIGP Administrative Domain as the BGP
speaker. speaker.
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will tend to pass the paths for which the IGP distance from the Route will tend to pass the paths for which the IGP distance from the Route
Reflector itself to the next hop is smallest. This may result in a Reflector itself to the next hop is smallest. This may result in a
non-optimal choice by the clients. non-optimal choice by the clients.
6. IANA Considerations 6. IANA Considerations
IANA has assigned the codepoint 26 in the "BGP Path Attributes" IANA has assigned the codepoint 26 in the "BGP Path Attributes"
registry to the AIGP attribute. registry to the AIGP attribute.
IANA shall create a registry for "BGP AIGP Attribute Types". The IANA shall create a registry for "BGP AIGP Attribute Types". The
type field consists of a single octet, with possible values from 0 to type field consists of a single octet, with possible values from 1 to
255. The allocation policy for this field is to be "Standards Action 255. (The value 0 is "reserved".) The allocation policy for this
with Early Allocation". Type 1 should be defined as "AIGP", and field is to be "Standards Action". Type 1 should be defined as
should refer to this document. "AIGP", and should refer to this document.
7. Security Considerations 7. Security Considerations
The spurious introduction, though error or malfeasance, of an AIGP The spurious introduction, though error or malfeasance, of an AIGP
attribute, could result in the selection of paths other than those attribute, could result in the selection of paths other than those
desired. desired.
Improper configuration on both ends of an EBGP connection could Improper configuration on both ends of an EBGP connection could
result in an AIGP attribute being passed from one service provider to result in an AIGP attribute being passed from one service provider to
another. This would likely result in an unsound selection of paths. another. This would likely result in an unsound selection of paths.
8. Acknowledgments 8. Acknowledgments
The authors would like to thank Waqas Alam, Rajiv Asati, Bruno The authors would like to thank Waqas Alam, Rajiv Asati, Ron Bonica,
Decraene, Brian Dickson, Clarence Filsfils, Anoop Kapoor, Pratima Bruno Decraene, Brian Dickson, Clarence Filsfils, Anoop Kapoor,
Kini, Sue Hares, Thomas Mangin, Robert Raszuk, Yakov Rekhter, Eric Pratima Kini, Sue Hares, Thomas Mangin, Robert Raszuk, Yakov Rekhter,
Rosenberg, Samir Saad, John Scudder, Shyam Sethuram, and Ilya Eric Rosenberg, Samir Saad, John Scudder, Shyam Sethuram, and Ilya
Varlashkin for their input. Varlashkin for their input.
9. Authors' Addresses 9. Authors' Addresses
Rex Fernando Rex Fernando
Cisco Systems, Inc. Cisco Systems, Inc.
170 Tasman Drive 170 Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
Email: rex@cisco.com Email: rex@cisco.com
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