draft-ietf-ospf-dc-04.txt   draft-ietf-ospf-dc-05.txt 
Network Working Group Sira Panduranga Rao Network Working Group Sira Panduranga Rao
Internet Draft UTA Internet Draft UTA
Expiration Date: March 2003 Alex Zinin Expiration Date: April 2003 Alex Zinin
File name: draft-ietf-ospf-dc-04.txt Alcatel File name: draft-ietf-ospf-dc-05.txt Alcatel
Abhay Roy Abhay Roy
Cisco Systems Cisco Systems
September 2002 October 2002
Detecting Inactive Neighbors over OSPF Demand Circuits Detecting Inactive Neighbors over OSPF Demand Circuits
draft-ietf-ospf-dc-04.txt draft-ietf-ospf-dc-05.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet Drafts are working documents of the Internet Engineering Internet Drafts are working documents of the Internet Engineering
Task Force (IETF), its Areas, and its Working Groups. Note that other Task Force (IETF), its Areas, and its Working Groups. Note that other
groups may also distribute working documents as Internet Drafts. groups may also distribute working documents as Internet Drafts.
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Drafts as reference material or to cite them other than as a "working Drafts as reference material or to cite them other than as a "working
draft" or "work in progress". draft" or "work in progress".
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
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Abstract Abstract
OSPF [RFC2328] is a link-state intra-domain routing protocol used in
IP networks. OSPF behavior over demand circuits is optimized in OSPF is a link-state intra-domain routing protocol used in IP
[RFC1793] to minimize the amount of overhead traffic. A part of OSPF networks. OSPF behavior over demand circuits is optimized in RFC1793
demand circuit extensions is the Hello suppression mechanism. This to minimize the amount of overhead traffic. A part of OSPF demand
technique allows a demand circuit to go down when no interesting circuit extensions is the Hello suppression mechanism. This technique
traffic is going through the link. However, it also introduces a allows a demand circuit to go down when no interesting traffic is
problem, where it becomes impossible to detect a OSPF-inactive going through the link. However, it also introduces a problem, where
neighbor over such a link. This memo addresses the above problem by it becomes impossible to detect a OSPF-inactive neighbor over such a
the neighbor probing mechanism. link. This memo addresses the above problem by the neighbor probing
mechanism.
1. Motivation 1. Motivation
In some situations, when operating over demand circuits, the remote In some situations, when operating over demand circuits, the remote
neighbor may be unable to run OSPF, and, as a possible result, unable neighbor may be unable to run OSPF, and, as a possible result, unable
to route application traffic. Possible scenarios include: to route application traffic. Possible scenarios include:
o The OSPF process might have died on the remote neighbor. o The OSPF process might have died on the remote neighbor.
o Oversubscription (Section 7 of [RFC1793]) may cause a o Oversubscription (Section 7 of [RFC1793]) may cause a
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5. Considerations 5. Considerations
In addition to the lost functionality mentioned in Section 6 of In addition to the lost functionality mentioned in Section 6 of
[RFC1793], there is an added overhead in terms of the amount of data [RFC1793], there is an added overhead in terms of the amount of data
(link state updates and acknowledgements) being transmitted due to (link state updates and acknowledgements) being transmitted due to
neighbor probing whenever the link is up and thereby increasing the neighbor probing whenever the link is up and thereby increasing the
overall cost. overall cost.
6. Acknowledgements 6. Acknowledgements
The original idea of limiting the number of LSA retransmissions on
demand circuits (used as part of the solution described in this
document) and its implementation belong to Padma Pillay-Esnault and
Derek Yeung.
The authors would like to thank John Moy, Vijayapal Reddy Patil, SVR The authors would like to thank John Moy, Vijayapal Reddy Patil, SVR
Anand, and Peter Psenak for their comments on this work. Anand, and Peter Psenak for their comments on this work.
A significant portion of Sira's work was carried out as part of the A significant portion of Sira's work was carried out as part of the
HFCL-IISc Research Project (HIRP), Bangalore, India. He would like to HFCL-IISc Research Project (HIRP), Bangalore, India. He would like to
thank the team for their insightful discussions. thank the team for their insightful discussions.
7. References 7. References
[RFC2328] [RFC2328]
J.Moy, OSPF Version 2. Technical Report RFC2328 Internet Engineer- J.Moy, OSPF Version 2. Technical Report RFC2328 Internet
ing Task Force, 1998 ftp://ftp.isi.edu/in-notes/rfc2328.txt Engineering Task Force, 1998 ftp://ftp.isi.edu/in-notes/rfc2328.txt
[RFC1793] [RFC1793]
J.Moy, Extending OSPF to support Demand Circuits. Technical Report J.Moy, Extending OSPF to support Demand Circuits. Technical Report
RFC1793 Internet Engineering Task Force, 1995 ftp://ftp.isi.edu/in- RFC1793 Internet Engineering Task Force, 1995 ftp://ftp.isi.edu/in-
notes/rfc1793.txt notes/rfc1793.txt
8. Authors' addresses 8. Authors' addresses
Sira Panduranga Rao Alex Zinin Sira Panduranga Rao Alex Zinin
The University of Texas at Arlington Alcatel The University of Texas at Arlington Alcatel
Arlington, TX 76013 Sunnyvale, CA Arlington, TX 76013 Sunnyvale, CA
Email: siraprao@hotmail.com E-mail: zinin@psg.com Email: siraprao@hotmail.com E-mail: zinin@psg.com
Abhay Roy Abhay Roy
Cisco Systems Cisco Systems
170 W. Tasman Dr. 170 W. Tasman Dr.
San Jose,CA 95134 San Jose,CA 95134
USA USA
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