Question on OSPF virtual-links computed via a router with in RFC-3137 "overload"
Don Goodspeed <dgoodspe@EXCITE.COM> Fri, 30 July 2004 20:54 UTC
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Date: Fri, 30 Jul 2004 16:53:28 -0400
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From: Don Goodspeed <dgoodspe@EXCITE.COM>
Subject: Question on OSPF virtual-links computed via a router with in RFC-3137 "overload"
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All, I have a question on a topology where I mix virtual-links with a router set in a RFC-3137 compliant "stub router" or "overload" state. BB<->Router A <--> Router B <--> Router C <--> Router D Area 0 ABR Area 1 Area 1 ABR Area 2 If everything lines up, Router A is an ABR between area 0 and area 1. Router C is an ABR between area 1 and area 2. I configure a virtual-link between routers A and C so router D can communicate to the backbone routers in area 0. If Router B is then set to an overload state compliant with RFC-3137, it advertises it's transit links with a metric of 65535. Router C then computes the cost of the virtual-link to A as 65535 + the metric of its link to B. My question is should the virtual-adjacency between A and C be declared down, or should A and C advertise the virtual-link metric in their router LSAs as 65535? This issue does not seem to be covered in either RFC-3137 or RFC-2328. This could also be done without an RFC-3137 situation by setting the path metrics such that the cost of the virtual- link also exceeds 65535. My feeling is that since the path metric exceeds 65535 the virtual adjacency should be torn down (since there is no better path between A and C). Any other opinions? Don _______________________________________________ Join Excite! - http://www.excite.com The most personalized portal on the Web!