NSSA problem

From: Hunt Lee (ciscoforme3@xxxxxxxxxxxx)
Date: Tue Aug 06 2002 - 10:34:14 GMT-3


   
Okay folks, starting off some late nite studying and just bumped into
another problem.

1.1.1.1/32 -- RTA -- RTB -- RTC -- RTD - 156.26.32.0/24 & 33.0/24

Both RTA, B & C are using OSPF.

RTA & RTB are in OSPF Area 0
RTB & RTC are in NSSA Area 1

RTC also uses RIP v2, so it's an ASBR
And RTD uses RIPv2

RTA's interface to RTB - 10.1.1.1
RTB's interface back to RTA - 10.1.1.2
RTB's interface to RTC - 10.1.1.5
RTC's interface back to RTB - 10.1.1.6
RTC's interface to RTD - 10.1.1.10
RTD's interface back to RTC - 10.1.1.9

RTD advertise the 2 networks 156.26.32.0/24 & 156.26.33.0/24 with
RIPv2.

RTC is doing mutual redistribution, where the RIPv2 is being
redistributed into OSPF, and OSPF is being redistributed back into
RIP.

Here's my question, RTA has a Loopback interface (1.1.1.1/32) and it
is being redistributed into OSPF at RTA:-

router ospf 1
 log-adjacency-changes
 redistribute connected subnets
 network 10.1.1.0 0.0.0.3 area 0

RouterA#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B -
BGP
      D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
     156.26.0.0/24 is subnetted, 2 subnets
O E2 156.26.32.0 [110/20] via 10.1.1.2, 01:36:22, Serial0
O E2 156.26.33.0 [110/20] via 10.1.1.2, 01:36:22, Serial0
     10.0.0.0/30 is subnetted, 3 subnets
O E2 10.1.1.8 [110/20] via 10.1.1.2, 01:36:22, Serial0
C 10.1.1.0 is directly connected, Serial0
O IA 10.1.1.4 [110/128] via 10.1.1.2, 01:37:34, Serial0
RouterA#

And at RTB, I can still see the route (1.1.1.1/32) as O E2...

RouterB#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B -
BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
O E2 1.1.1.1 [110/20] via 10.1.1.1, 01:37:18, Serial0
     2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
     156.26.0.0/24 is subnetted, 2 subnets
O N2 156.26.32.0 [110/20] via 10.1.1.6, 01:37:18, Serial1
O N2 156.26.33.0 [110/20] via 10.1.1.6, 01:37:18, Serial1
     10.0.0.0/30 is subnetted, 3 subnets
O N2 10.1.1.8 [110/20] via 10.1.1.6, 01:37:18, Serial1
C 10.1.1.0 is directly connected, Serial0
C 10.1.1.4 is directly connected, Serial1
RouterB#

But at RTC, the route disappears!!!

RouterC#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B -
BGP
      D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is not set

     3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback0
     156.26.0.0/24 is subnetted, 2 subnets
R 156.26.32.0 [120/1] via 10.1.1.9, 00:00:02, Serial1
R 156.26.33.0 [120/1] via 10.1.1.9, 00:00:02, Serial1
     10.0.0.0/30 is subnetted, 3 subnets
C 10.1.1.8 is directly connected, Serial1
O IA 10.1.1.0 [110/128] via 10.1.1.5, 01:38:50, Serial0
C 10.1.1.4 is directly connected, Serial0
RouterC#

RouterB#sh ip ospf database

            OSPF Router with ID (2.2.2.2) (Process ID 2)

                Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 1655 0x80000005 0x6B0D 2
2.2.2.2 2.2.2.2 984 0x80000008 0x867 2

                Summary Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum
10.1.1.4 2.2.2.2 1728 0x80000004 0xF5EE

                Router Link States (Area 1)

Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 984 0x80000009 0xC787 2
10.1.1.10 10.1.1.10 874 0x80000007 0x54EE 2

                Summary Net Link States (Area 1)

Link ID ADV Router Age Seq# Checksum
10.1.1.0 2.2.2.2 984 0x80000006 0xBF21

                Type-7 AS External Link States (Area 1)

Link ID ADV Router Age Seq# Checksum Tag
10.1.1.8 10.1.1.10 876 0x80000004 0x87D2 0
156.26.32.0 10.1.1.10 876 0x80000004 0xF49F 0
156.26.33.0 10.1.1.10 876 0x80000004 0xE9A9 0

                Type-5 AS External Link States

Link ID ADV Router Age Seq# Checksum Tag
1.1.1.1 1.1.1.1 1657 0x80000004 0x95FF 0
10.1.1.8 2.2.2.2 985 0x80000004 0x85EC 0
156.26.32.0 2.2.2.2 985 0x80000004 0xF2B9 0
156.26.33.0 2.2.2.2 985 0x80000004 0xE7C3 0
RouterB#

RouterC#sh ip ospf database

            OSPF Router with ID (10.1.1.10) (Process ID 3)

           Router Link States (Area 1)

Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 1136 0x80000009 0xC787 2
10.1.1.10 10.1.1.10 1024 0x80000007 0x54EE 2

           Summary Net Link States (Area 1)

Link ID ADV Router Age Seq# Checksum
10.1.1.0 2.2.2.2 1136 0x80000006 0xBF21

           Type-7 AS External Link States (Area 1)

Link ID ADV Router Age Seq# Checksum Tag
10.1.1.8 10.1.1.10 1024 0x80000004 0x87D2 0
156.26.32.0 10.1.1.10 1024 0x80000004 0xF49F 0
156.26.33.0 10.1.1.10 1024 0x80000004 0xE9A9 0
RouterC#

I always thought what NSSA does is to allow one to create a Stubby or
Totally Stubby Area and also be able to advertise redistributed
routes into / across this Stub Area. Did I missed something simple
here??

Thanks,
H.

http://digital.yahoo.com.au - Yahoo! Digital How To
- Get the best out of your PC!



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