If there is no back link, there is no link, and SPF moves on. If the
network is partitioned, somebody should fix it.
Ignoring the bidirectional test rule can lead to loops and black
holes, particularly if other implementations are following the rules.
--Dave
On Aug 6, 2009, at 8:02 AM, Joakim Tjernlund wrote:
"Joel M. Halpern" <[email protected]> wrote on 06/08/2009 15:38:47:
I am not sure what you are asking. A link advertised in OSPF may
only
be used if it is advertised in both directions.
Exactly, so you may encounter the scenario below when links are going
down/up until all routers has recalculated everything.
Therefore, it appears taht the case you are describing can not occur.
It can, so when it does you can either just give up or try
to do the best you can until you find a back link.
Jocke
PS.
Please keep the ospf list on the CC: line.
Yours,
Joel
Joakim Tjernlund wrote:
In "16.1.1. The next hop calculation" one have:
In the second case, the parent vertex is a network that
directly connects the calculating router to the
destination
router. The list of next hops is then determined by
examining the destination's router-LSA. For each link in
the router-LSA that points back to the parent network,
the
link's Link Data field provides the IP address of a
next hop
router. The outgoing interface to use can then be
derived
from the next hop IP address (or it can be inherited from
the parent network).
Suppose that one cannot find any links that points back, is it a
good
idea to treat this case as a intervening router:
If there is at least one intervening router in the
current
shortest path between the destination and the root, the
destination simply inherits the set of next hops from the
parent.
That is, just inherit the next hops from its parents?
Jocke
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