draft-ietf-grow-simple-va-10.txt   draft-ietf-grow-simple-va-11.txt 
GROW Working Group R. Raszuk GROW Working Group R. Raszuk
Internet-Draft NTT MCL Internet-Draft NTT MCL
Intended status: Informational J. Heitz Intended status: Informational J. Heitz
Expires: January 6, 2013 Ericsson Expires: January 2, 2013 Ericsson
A. Lo A. Lo
Arista Arista
L. Zhang L. Zhang
UCLA UCLA
X. Xu X. Xu
Huawei Huawei
July 5, 2012 July 2012
Simple Virtual Aggregation (S-VA) Simple Virtual Aggregation (S-VA)
draft-ietf-grow-simple-va-10.txt draft-ietf-grow-simple-va-11.txt
Abstract Abstract
All BGP routers in the Default Free Zone (DFZ) are required to carry All BGP routers in the Default Free Zone (DFZ) are required to carry
all the routes in the Default Free Routing Table (DFRT). A technique all the routes in the Default Free Routing Table (DFRT). A technique
is described that allows some BGP routers not to install all of those is described that allows some BGP routers not to install all of those
routes into the Forwarding Information Base (FIB). routes into the Forwarding Information Base (FIB).
Some routers in an Autonomous System (AS) announce an aggregate (the Some routers in an Autonomous System (AS) announce an aggregate (the
VA prefix) in addition to the routes they already announce. This VA prefix) in addition to the routes they already announce. This
enables other routers not to install the routes covered by the VA enables other routers not to install the routes covered by the VA
prefix into the FIB as long as those routes have the same next-hop as prefix into the FIB as long as those routes have the same next-hop as
the VA prefix. the VA prefix.
The VA prefixes that are announced within an AS are not announced to The VA prefixes that are announced within an AS are not announced to
any other AS. any other AS. In contrast to VA, S-VA reduces operational complexity
by proposing local to given BGP speaker solution without any
dependency on network wide configuration or requires presence of any
form of intra-domain tunneling.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on January 6, 2013. This Internet-Draft will expire on January 2, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 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
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publication of this document. Please review these documents publication of this document. Please review these documents
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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
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Scope of this Document . . . . . . . . . . . . . . . . . . 3 1.1. Scope of this Document . . . . . . . . . . . . . . . . . . 4
1.2. Requirements notation . . . . . . . . . . . . . . . . . . . 3 1.2. Requirements notation . . . . . . . . . . . . . . . . . . . 4
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Operation of S-VA . . . . . . . . . . . . . . . . . . . . . . . 4 2. Operation of S-VA . . . . . . . . . . . . . . . . . . . . . . . 5
3. Deployment considerations . . . . . . . . . . . . . . . . . . . 6 3. Deployment considerations . . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
A technique called Simple Virtual Aggregation (S-VA) is described. A technique called Simple Virtual Aggregation (S-VA) is described.
It allows some routers not to have to store some routes in the It allows some routers not to have to store some routes in the
Forwarding Information Base (FIB) while still advertising and Forwarding Information Base (FIB) while still advertising and
receiving the full Default Free Routing Table (DFRT) in BGP. receiving the full Default Free Routing Table (DFRT) in BGP.
A typical scenario is as follows. Core routers in the ISP maintain A typical scenario is as follows. Core routers in the ISP maintain
the full DFRT in the FIB and RIB. Edge routers maintain the full the full DFRT in the FIB and RIB. Edge routers maintain the full
skipping to change at page 4, line 14 skipping to change at page 5, line 14
Suppress: Not to install a route that is covered by the VA-prefix Suppress: Not to install a route that is covered by the VA-prefix
into the global RIB or FIB into the global RIB or FIB
Legacy Router: A router that does not run S-VA, and has no knowledge Legacy Router: A router that does not run S-VA, and has no knowledge
of S-VA. of S-VA.
Global Routing Information Base (RIB): All the routing protocols in Global Routing Information Base (RIB): All the routing protocols in
a router install their selected routes into the RIB. The routes a router install their selected routes into the RIB. The routes
in the RIB are used to resolve next-hops for other routes, to be in the RIB are used to resolve next-hops for other routes, to be
redistributed to other routing protocols and to be installed into redistributed to other routing protocols and to be installed into
the FIB. the FIB.
Local/Protocol Routing Information Base (loc-RIB): The Loc-RIB Local/Protocol Routing Information Base (Loc-RIB): The Loc-RIB
contains the routes that have been selected by the local BGP contains the routes that have been selected by the local BGP
speaker's Decision Process as in [RFC4271]. speaker's Decision Process as in [RFC4271].
NLRI: Network Layer Reachability Information [RFC4271] NLRI: Network Layer Reachability Information [RFC4271]
2. Operation of S-VA 2. Operation of S-VA
There are three types of routers in S-VA, FIB-Installing routers There are three types of routers in S-VA, FIB-Installing routers
(FIR), FIB-Suppressing routers (FSR) and optionally, legacy routers. (FIR), FIB-Suppressing routers (FSR) and optionally, legacy routers.
While any router can be an FIR or an FSR, the simplest form of While any router can be an FIR or an FSR, the simplest form of
deployment is for AS border routers to be configured as FIRs and for deployment is for AS border routers to be configured as FIRs and for
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reachability of any destination, a router can be configured not to reachability of any destination, a router can be configured not to
resolve next-hops using the default route. In this case, S-VA should resolve next-hops using the default route. In this case, S-VA should
not suppress from installation into the RIB a route that may be used not suppress from installation into the RIB a route that may be used
to resolve a next-hop for another route. It may still suppress it to resolve a next-hop for another route. It may still suppress it
from installation into the FIB from installation into the FIB
Selected BGP routes in the RIB may be redistributed to other Selected BGP routes in the RIB may be redistributed to other
protocols. If they no longer exist in the RIB, they will not be protocols. If they no longer exist in the RIB, they will not be
redistributed. This is especially important when the conditional redistributed. This is especially important when the conditional
redistribution is taking place based on the length of the prefix, redistribution is taking place based on the length of the prefix,
community value etc .. In those cases where redistribution policy is community value etc. In those cases where redistribution policy is
in place S-VA code should refrain from suppressing from installation in place S-VA code should refrain from suppressing from installation
into the RIB routes matching such policy. It may still suppress them into the RIB routes matching such policy. It may still suppress them
from installation into the FIB. from installation into the FIB.
A router may originate a network route or an aggregate route into A router may originate a network route or an aggregate route into
BGP. Some addresses covered by such a route may not exist. If this BGP. Some addresses covered by such a route may not exist. If this
router were to receive a packet for an unreachable address within an router were to receive a packet for an unreachable address within an
originated route, it must not send that packet to the VA-prefix originated route, it must not send that packet to the VA-prefix
route. There are several ways to achieve this. One is to have the route. There are several ways to achieve this. One is to have the
FIR aggregate the routes instead of the FSR. Another is to install a FIR aggregate the routes instead of the FSR. Another is to install a
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