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Re: OSPF NSSA problems posted 09/23/2008
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Peter Wolter wrote:
Dear Bogdan,

Thanks your remind and I agree it's strange also.
Can you show the result of
show ip ospf database externa 158.1.0.0
on SW4? I wanna to know which router redistribute this route to SW4
Regards,
Howard
I already replied to this - but just in case the reply didn't make it, here it is again:

Of course - the subnet is redistributed by R3 (the router at the other end of the two areas), using a "redistribute connected" statement (in the original lab, the subnet was redistributed from EIGRP, with the same result).

/Rack1SW4#sh ip ospf data ex 158.1.0.0

OSPF Router with ID (150.1.10.10) (Process ID 1)

Type-5 AS External Link States

Routing Bit Set on this LSA
LS age: 131
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 158.1.0.0 (External Network Number )
Advertising Router: 150.1.3.3
LS Seq Number: 80000001
Checksum: 0x5310
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0/
The route is advertised by 150.1.3.3 (R3), with a forwarding address of 0.0.0.0 .


SW4 has only one routing table entry for 150.1.3.3 (as expected, it only uses the intra-area route):
/
Rack1SW4#sh ip ro 150.1.3.3
Routing entry for 150.1.3.3/32
Known via "ospf 1", distance 110, metric 66, type intra area
Last update from 158.1.1.1 on Vlan110, 00:03:07 ago
Routing Descriptor Blocks:
* 158.1.1.1, from 150.1.3.3, 00:03:07 ago, via Vlan110
Route metric is 66, traffic share count is 1/


However, it still installs two routes for the external address:

/Rack1SW4#sh ip ro 158.1.0.0 255.255.255.0
Routing entry for 158.1.0.0/24
Known via "ospf 1", distance 110, metric 20, type extern 2, forward metric 65
Last update from 158.1.1.1 on Vlan110, 00:05:03 ago
Routing Descriptor Blocks:
* 158.1.34.1, from 150.1.3.3, 00:05:03 ago, via FastEthernet1/13
Route metric is 20, traffic share count is 1
158.1.1.1, from 150.1.3.3, 00:05:03 ago, via Vlan110
Route metric is 20, traffic share count is 1


/ If you need any additional details/output, please let me know (I would also draw a diagram, but I really don't know how I could put this topology in ASCII format :) ).

Thank you for your help,



--
Bogdan Sass
CCAI,CCNP,CCSP,JNCIA-ER
Information Systems Security Professional
"Curiosity was framed - ignorance killed the cat"