[Xorp-users] Still too long switching time

Atanu Ghosh atanu@ICSI.Berkeley.EDU
Wed, 08 Feb 2006 12:23:16 -0800


Hi,

Once the SPF computation has been triggered there are no other
configured delays that I can remember. If as a result of the SPF
computation routes have changed then the delta route information is sent
to the RIB. If the routes from OSPF win over routes from other protocols
the routes are sent to the FEA. The FEA then adds or deletes the routes
from the kernel.

Please note a new LSA may trigger a SPF computation but this doesn't
have to mean that the routing table will change.

The other thing to note is that SPF computation in OSPF is only part of
the routing computation. In the base OSPF specification five different
LSAs are defined, the SPF computation only uses two LSAs (router-LSA
and network-LSA). After the SPF computation is performed the
summary-LSAs and AS-External-LSAs are processed to see if the networks
they describe are reachable via the graph built in the SPF computation.

     Atanu.

>>>>> "riccardo" == riccardo  <riccardo.sciaccaluga@tin.it> writes:

    riccardo> according to the ospf experiment i did and taking in
    riccardo> account xorp router_recompute_delay of 5 secs....i still
    riccardo> found a switching time of almost two seconds.  Because of
    riccardo> i placed a timestamp in dijkstra calculation and because i
    riccardo> saw that dijkstra calcultion employ just 0,1s ......i
    riccardo> don't know why the switching time is around 2 sec.  Are
    riccardo> there any other delay setted up on ospf code?...like a
    riccardo> delay between calculating the new best route and placing
    riccardo> it inside the rotuing table or something like that?
    riccardo> _______________________________________________ Xorp-users
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    riccardo> http://mailman.ICSI.Berkeley.EDU/mailman/listinfo/xorp-users