Network Working Group S.Tsuchiya
Internet-Draft Cisco Systems
Intended status: Informational T.Yamagata
Expires:August 31,2010 KDDI Corporation
May 30, 2010
OSPFv3 Stub Router Advertisement
draft-shishio-ospf-ospfv3-stub-00
Abstract
Open Shortest Path First for IPv6 has no transit capability,it is R-bit
and V6-bit.
The feature can avoid transit when the router does not ready to forward
packets.This is very useful feature for operators.
But Stub Router advertisment is very popular operation method on
Open Shortest Path First IPv4 enviroments.
This document describe about OSPFv3 Stub Router Advertisemnt for easy
to operate OSPFv2 and OSPFv3 dual stack environments.
Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 31, 2010.
Shishio Tsuchiya,et al Expires August 31,2010 [Page 1]
Internet-Draft OSPFv3 Stub Router Advertisement 2010
Copyright Notice
Copyright (c) 2010 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
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. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. OSPFv2 operation. . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Wait for BGP when bootup. . . . . . . . . . . . . . . . . . 3
2.2 LDP syncronization. . . . . . . . . . . . . . . . . . . . . 3
2.3 Configuration change. . . . . . . . . . . . . . . . . . . . 4
3. OSPFv3 operation. . . . . . . . . . . . . . . . . . . . . . . . 4
3.1 R-bit and v6-bit . . . . . . . . . . . . . . . . . . . . . . 4
3.2 OSPFv2 compatibility mode. . . . . . . . . . . . . . . . . . 4
4. Security Considerations. . . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . 5
Shishio Tsuchiya,et al Expires August 31,2010 [Page 2]
Internet-Draft OSPFv3 Stub Router Advertisement 2010
1. Motivation
OSPF Stub Router Advertisement[RFC3137] describe when the operator
need this function.
o The router is in a critical condition (for example, has very
high CPU load or does not have enough memory to store all LSAs
or build the routing table).
o Graceful introduction and removal of the router to/from the
network.
o Other (administrative or traffic engineering) reasons.
Even if the network will be moved or migrated to IPv6 with OSPFv3
[OSPFv3],but the motivation never change.
2. OSPFv2 operation
[RFC3137] described in section 2 in detail.
Router X announce its Router LSA to the neighbor with costs of all
non-stub links are set to LSInfinity(0xFFFF).
The operater will check interface metric of ospf database,if he would
like to confirm whether the router anounce LSInginity.
Many operators are using [RFC3137] in OSPFv2.And a lot of venders
support this feature.
Use cases are below;
2.1 Wait for BGP when bootup.
|R1|--|R2|---|R4|---internet
| |
+----|R3|-----+
R2 is best path for internet.
When R2 reload,then R3 would be best for internet.
R2 is bootup and OSPF converged,but BGP still not conveged.
R1 should not send traffic to R3.
So R2 sends LSInfinity(0xFFFF),R1 wait R2-R4's BGP converge.
BGP converged,R2 sends correct metric value in OSPFv2 area.
R2 back to primary path.
2.2 LDP syncronization
|R1|--|R2|---|R4|
| |
+----|R3|-----+
R2 is best path in this MPLS network.
When R2 reload,then R3 would be best path.
R2 is bootup and OSPF converged,but LDP not converged.
R1 should not send traffic to R3.
So R2 sends LSInfinity(0xFFFF),R1 wait R2 LDP converged.
LDP converged,R2 sends correct metric value in OSPFv2 area.
And OSPF and LDP converged.
This operation is described in [LDP-Sync].
Shishio Tsuchiya, Expires [Page 3]
Internet-Draft OSPFv3 Stub Router Advertisement 2010
2.3 Configuration change
|R1|--|R2|---|R4|
| |
+----|R3|-----+
When operator needs R2 configuration change,R2 sends LSInfinity(0xFFFF)
for traffic engineering.
R2 configuration completed,R2 sends correct metric value
in OSPFv2 area.
3. OSPFv3 operation
3.1 R-bit and v6-bit
[RFC5340] explains section 2.7.
If the "R-bit" is clear, an OSPF speaker can participate in OSPF
topology distribution without being used to forward transit traffic.
The V6-bit specializes the R-bit; if the V6-bit is clear, an OSPF
speaker can participate in OSPF topology distribution without
being used to forward IPv6 datagrams. If the R-bit is set and the
V6-bit is clear, IPv6 datagrams are not forwarded but datagrams
belonging to another protocol family may be forwarded.
This protocol implementation is useful in multi address family
environment such as [OSPFv3 AF].
Operetor have to check "R-bit" and "v6-bit" in this operations
not mettric.
Also [RFC5340] described in A.2. The Options Field.
R-bit
This bit (the `Router' bit) indicates whether the originator is
an active router. If the router bit is clear, then routes that
transit the advertising node cannot be computed.
[RFC3137] is just maximum metric,the route is compted,
but the worst.
When R3 and R3's link failed in 2.3 Configuration change.
R1 sends traffic to R2.
But if R-bit clear,R1 can't sends traffic to R2.
Because the route is not computed.
3.2. OSPFv2 compatibility mode
OSPFv3 has metric information of all of LSAs(except of Link-LSA.)
So,the router can annouce set to LSInfinity(0xFFFF).
This is simple implementation and operation.
4. Acknowledgements
Shishio Tsuchiya, Expires [Page 4]
Internet-Draft OSPFv3 Stub Router Advertisement 2010
5. Security Considerations
The technique described in this document does not introduce any new
security issues into OSPF protocol.
6. References
[OSPFv2] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC3137] "OSPF Stub Router Advertisement",RFC3137, June 2001.
[OSPFv3] "OSPF for IPv6" RFC5330,July 2008
[OSPFv3 AF] "Support of Address Families in OSPFv3" ,RFC5838 April 2010
[LDP Sync] "LDP IGP Synchronization",RFC5443 March 2009
Authors' Addresses
Shishio Tsuchiya
Cisco Systems G.K.
Shinjuku Mitsui Building,
2-1-1, Nishi-Shinjuku, Shinjuku-Ku
Tokyo,JAPAN
e-mail: shtsuchi@cisco.com
Tomohiro Yamagata
KDDI Corporation
Garden Air Tower
Iidabashi
Chiyoda-ku, Tokyo 102-8460
JAPAN
e-mail: to-yamagata@kddi.com
Shishio Tsuchiya,et al Expires August 31,2010 [Page 5]
Internet-Draft OSPFv3 Stub Router Advertisement 2010