Hello,
We currently have Layer 3 Routed Access configured at all of our Metro Campus
locations. There are a few obvious deviations from the best practice design
guides. The current setup is:
Core --> Datacenter Distribution --> | (fiber connect) | -->
Building Distribution --> Access
(backbone) (ABR)
(ASBR) (OSPF enabled access
switch)
The Cisco best practice is:
Core --> Distribution --> Access
(backbone) (ABR) (OSPF enabled access switch)
We are running NSSA with no-summary and the range command on the Datacenter
Distribution routers. Each floor has 2 access switches (w/ OSPF running) which
each have a link back to the Building Distribution router. Vlans on each box
on each floor are mutually exclusive.
Symptoms:
Lots of SPF re-calculations, NTP failing from Datacenter Distro -> Building
Distro, and users reporting loss of their shared drives.
router-a#sh ip ospf stat
Area 0.0.0.0: SPF algorithm executed 7865 times
Area 192.8.208.0: SPF algorithm executed 386 times
Area 192.70.0.0: SPF algorithm executed 563 times
Area 192.100.0.0: SPF algorithm executed 93076 times
Questions:
Should we be advertising (passively or non-passively) L3 Vlans into OSPF?
Should we be doing Totally NSSA's instead of NSSA's?
If not is there a way to get the DR in NSSA to advertise a single route
back as default route?
Should we be sending each campus distribution router directly to the Core so
that its the 3 hops?
Do you suggest tuning the OSPF dead interval to achieve subsecond convergence?
Any help advise is greatly appreciated!
Regards,
//LeBlanc
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