Network Working Group A. Lindem
Internet-Draft Redback Networks
Intended status: Standards Track A. Roy
Expires: March 28, 2009 Cisco Systems
S. Mirtorabi
Nuova Systems
September 24, 2008
OSPF Transport Instance Extensions
draft-acee-ospf-transport-instance-01.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of 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 March 28, 2009.
Copyright Notice
Copyright (C) The IETF Trust (2008).
Lindem, et al. Expires March 28, 2009 [Page 1]
Internet-Draft OSPF Transport Instance Extensions September 2008
Abstract
OSPFv2 and OSPFv3 include a reliable flooding mechanism to
disseminate routing topology and Traffic Engineering (TE) information
within a routing domain. Given the effectiveness of these
mechanisms, it is convenient to envision using the same mechanism for
dissemination of other types of information within the domain.
However, burdening OSPF with this additional information will impact
intra-domain routing convergence and possibly jeopardize the
stability of the OSPF routing domain. This document presents
mechanism to relegate this ancillary information to a separate OSPF
instance and minimize the impact.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3
2. OSPF Transport Instance . . . . . . . . . . . . . . . . . . . 4
2.1. OSPFv2 Transport Instance Packets Differentiation . . . . 4
2.2. OSPFv3 Transport Instance Packets Differentiation . . . . 4
2.3. Instance Relationship to Normal OSPF Instances . . . . . . 4
2.3.1. Ships in the Night Relationship to Normal OSPF
Instances . . . . . . . . . . . . . . . . . . . . . . 4
2.3.2. Tigher Coupling with Normal OSPF Instances . . . . . . 5
2.4. Network Prioritization . . . . . . . . . . . . . . . . . . 5
3. OSPF Transport Instance Information Encoding . . . . . . . . . 6
3.1. OSPFv2 Transport Instance Information Encoding . . . . . . 6
3.2. OSPFv3 Transport Instance Information Encoding . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Normative References . . . . . . . . . . . . . . . . . . . . . 9
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . . . . 12
Lindem, et al. Expires March 28, 2009 [Page 2]
Internet-Draft OSPF Transport Instance Extensions September 2008
1. Introduction
OSPFv2 [OSPFV2] and OSPFv3 [OSPFV3] include a reliable flooding
mechanism to disseminate routing topology and Traffic Engineering
(TE) information within a routing domain. Given the effectiveness of
these mechanisms, it is convenient to envision using the same
mechanism for dissemination of other types of information within the
domain. However, burdening OSPF with this additional information
will impact intra-domain routing convergence and possibly jeopardize
the stability of the OSPF routing domain. This document presents
mechanism to relegate this ancillary information to a separate OSPF
instance and minimize the impact.
1.1. Requirements notation
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-KEYWORDS].
Lindem, et al. Expires March 28, 2009 [Page 3]
Internet-Draft OSPF Transport Instance Extensions September 2008
2. OSPF Transport Instance
In order to isolate the overhead of flooding non-routing information,
its flooding will be relegated to a separate protocol instance. This
instance should be given lower priority when contending for router
resources including processing, backplane bandwidth, and line card
bandwidth. How that is realized is an implementation issue and is
beyond the scope of this document.
2.1. OSPFv2 Transport Instance Packets Differentiation
OSPFv2 currently doesn't offer a mechanism to differentiate Transport
instance packets from normal instance packets sent and received on
the same interface. However, the [MULTI-INST] provides the necessary
packet encoding to support multiple OSPF protocol instances.
2.2. OSPFv3 Transport Instance Packets Differentiation
Fortunately, OSPFv3 already supports separate instances within the
packet encodings. The existing OSPFv3 packet header instance ID
field will be used to differentiate packets received on the same link
(refer to section 2.4 in [OSPFV3]).
2.3. Instance Relationship to Normal OSPF Instances
There are basically two alternatives for the relationship between a
normal OSPF instance and a Transport Instance. In both cases, we
must guarantee that any information we've received is treated as
valid if and only if the router sending it is reachable. We'll refer
to this as the "condition of reachability" in this document.
1. Ships in the Night - The Transport Instance has no relationship
or dependency on any other OSPF instance.
2. Child Instance - The Transport Instance has a child-parent
relationship with a normal OSPF instance and is dependent on this
for topology information and assuring the "condition of
reachability".
2.3.1. Ships in the Night Relationship to Normal OSPF Instances
In this mode, the Transport Instance is not dependent on any other
OSPF instance. It does, however, have much of the overhead as
topology information must be advertised to satisfy the condition of
reachability.
Prefix information does this need to be advertised. This implies
that for OSPFv2, only router-LSAs, network-LSAs, and type 4 summary-
Lindem, et al. Expires March 28, 2009 [Page 4]
Internet-Draft OSPF Transport Instance Extensions September 2008
LSAs need to be advertised. In the router-LSAs, the stub (type 3)
links may be suppressed. For OSPFv3, this implies that router-LSAs,
Network-LSAs, and inter-area-router-LSAs must be advertised.
2.3.2. Tigher Coupling with Normal OSPF Instances
Further optimization and coupling between the transport instance and
a normal OSPF instance are beyond the scope of this document. This
is an area for future study.
2.4. Network Prioritization
While OSPFv2 (section 4.3 in [OSPFV2]) are normally sent with IP
precedence Internetwork Control, any packets sent by a transport
instance will be sent with IP precedence Flash (B'011'). This is
only appropriate given that this is a pretty flashy mechanism.
OSPFv3 packet prioritization is under discussion although it is not
in the current specification ([OSPFV3]). It is expected that this
will be in the next revision of the OSPFv3 specification.
Lindem, et al. Expires March 28, 2009 [Page 5]
Internet-Draft OSPF Transport Instance Extensions September 2008
3. OSPF Transport Instance Information Encoding
The format of the TLVs within the body of an LSA containing non-
routing information is the same as the format used by the Traffic
Engineering Extensions to OSPF [TE]. The LSA payload consists of one
or more nested Type/Length/Value (TLV) triplets. The format of each
TLV is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Format
However, each unique application using the mechanisms defined in this
document will have it's own unique ID. Whether to encode this ID as
the top-level TLV or make it part of the OSPF LSA ID is open for
debate.
The specific TLVs and sub-TLVs relating to a given application and
the corresponding IANA considerations MUST for standard applications
MUST be specified in the document corresponding to that application.
3.1. OSPFv2 Transport Instance Information Encoding
Application specific information will be flooded in opaque LSAs as
specified in [OPAQUE].
3.2. OSPFv3 Transport Instance Information Encoding
Application specific information will be flooded in separate LSAs
with separate function codes. Refer to section A.4.2.1 of [OSPFV3]
for information on the LS Type encoding in OSPFv3.
Lindem, et al. Expires March 28, 2009 [Page 6]
Internet-Draft OSPF Transport Instance Extensions September 2008
4. Security Considerations
The security considerations for the Transport Instance will not be
different for those for OSPFv2 [OSPFV2] and OSPFv3 [OSPFV3].
Lindem, et al. Expires March 28, 2009 [Page 7]
Internet-Draft OSPF Transport Instance Extensions September 2008
5. IANA Considerations
No new IANA assignments are required for this draft.
Lindem, et al. Expires March 28, 2009 [Page 8]
Internet-Draft OSPF Transport Instance Extensions September 2008
6. Normative References
[MULTI-INST]
Lindem, A., Mirtorabi, S., and A. Roy, "OSPF Multi-
Instance Extensions",
draft-acee-ospf-multi-instance-02.txt (work in progress).
[OPAQUE] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
OSPF Opaque LSA Option", RFC 5250, July 2008.
[OSPFV2] Moy, J., "OSPF Version 2", RFC 2328, April 1998.
[OSPFV3] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, July 2008.
[RFC-KEYWORDS]
Bradner, S., "Key words for use in RFC's to Indicate
Requirement Levels", RFC 2119, March 1997.
[TE] Katz, D., Yeung, D., and K. Kompella, "Traffic Engineering
Extensions to OSPF", RFC 3630, September 2003.
Lindem, et al. Expires March 28, 2009 [Page 9]
Internet-Draft OSPF Transport Instance Extensions September 2008
Appendix A. Acknowledgments
The RFC text was produced using Marshall Rose's xml2rfc tool.
Lindem, et al. Expires March 28, 2009 [Page 10]
Internet-Draft OSPF Transport Instance Extensions September 2008
Authors' Addresses
Acee Lindem
Redback Networks
102 Carric Bend Court
Cary, NC 27519
USA
Email: acee@redback.com
Abhay Roy
Cisco Systems
225 West Tasman Drive
San Jose, CA 95134
USA
Email: akr@cisco.com
Sina Mirtorabi
Nuova Systems
3 West Plumeria Drive
San Jose, CA 95134
USA
Email: sina@nuovasystems.com
Lindem, et al. Expires March 28, 2009 [Page 11]
Internet-Draft OSPF Transport Instance Extensions September 2008
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Lindem, et al. Expires March 28, 2009 [Page 12]