RE: IBGP redistribution mystery

From: Ouellette, Tim (tim.ouellette@eds.com)
Date: Sat Feb 22 2003 - 04:57:43 GMT-3


Well here goes. I labbed this up, wondering what kinda "stuff" I would see
so here goes......
Hopefully I'm setting this up as Hunt did...

r9--------------r8--------------r7--------------r6
   area1 area0 area67 NSSA
  10.1.89.x/24 10.1.78.x/24 10.1.67.x/24

R9 peers via ibgp to r7 (as3)
r9 to r8 is area 1(10.1.89.x/24)
r8 to r7 is area 0(10.1.78.x/24)
r7 to r6 is area 67 NSSA (10.1.67.x/24)

Each router has a loopback with there router number x 4 octets (r9 is
9.9.9.9)

r9 is generating 99.0.0.0 and sending it via ibgp to r7.
I redistributed that ibgp learned router into ospf on r7 and it showed up as
   a type 5 into area 0 and a type 7 into the NSSA area

Although routing works a little weird because r7 thinks to get to 99.0.0.0
via 9.9.9.9 but with a nexthop of 10.1.78.8 but r8 doesn't know how to get
there via OSPF so there are routing issues (but that wasn't the point of the
lab)

Below are the appropriate configs.......

r9
router ospf 1
 router-id 9.9.9.9
 log-adjacency-changes
 network 9.9.9.9 0.0.0.0 area 1
 network 10.1.89.9 0.0.0.0 area 1
!
router bgp 3
 no synchronization
 bgp log-neighbor-changes
 network 99.0.0.0
 neighbor 7.7.7.7 remote-as 3

r8
router ospf 1
 router-id 8.8.8.8
 log-adjacency-changes
 network 8.8.8.8 0.0.0.0 area 0
 network 10.1.78.8 0.0.0.0 area 0
 network 10.1.89.8 0.0.0.0 area 1

r8#r

O E2 99.0.0.0/8 [110/20] via 10.1.78.7, 00:10:08, Ethernet2
     6.0.0.0/32 is subnetted, 1 subnets
O IA 6.6.6.6 [110/75] via 10.1.78.7, 00:11:51, Ethernet2
     7.0.0.0/24 is subnetted, 1 subnets
O 7.7.7.0 [110/11] via 10.1.78.7, 00:11:51, Ethernet2
     8.0.0.0/32 is subnetted, 1 subnets
C 8.8.8.8 is directly connected, Loopback0
     9.0.0.0/32 is subnetted, 1 subnets
O 9.9.9.9 [110/65] via 10.1.89.9, 00:11:51, Serial1
     10.0.0.0/24 is subnetted, 3 subnets
C 10.1.78.0 is directly connected, Ethernet2
O IA 10.1.67.0 [110/74] via 10.1.78.7, 00:11:52, Ethernet2
C 10.1.89.0 is directly connected, Serial1
     60.0.0.0/24 is subnetted, 1 subnets
O E2 60.60.60.0 [110/5] via 10.1.78.7, 00:09:55, Ethernet2

r7
router ospf 1
 router-id 7.7.7.7
 log-adjacency-changes
 area 67 nssa default-information-originate
 area 67 default-cost 20
 redistribute bgp 3 metric 20 subnets
 network 7.7.7.7 0.0.0.0 area 0
 network 10.1.67.7 0.0.0.0 area 67
 network 10.1.78.7 0.0.0.0 area 0
!
router bgp 3
 no synchronization
 bgp redistribute-internal
 bgp log-neighbor-changes
 neighbor 9.9.9.9 remote-as 3
 neighbor 9.9.9.9 update-source Loopback0

r7#r
B 99.0.0.0/8 [200/20] via 9.9.9.9, 00:12:13 <--- this is the one
were looking for in OSPF
     6.0.0.0/32 is subnetted, 1 subnets
O 6.6.6.6 [110/65] via 10.1.67.6, 00:12:14, Serial1
     7.0.0.0/24 is subnetted, 1 subnets
C 7.7.7.0 is directly connected, Loopback0
     8.0.0.0/32 is subnetted, 1 subnets
O 8.8.8.8 [110/11] via 10.1.78.8, 00:12:14, Ethernet2
     9.0.0.0/32 is subnetted, 1 subnets
O IA 9.9.9.9 [110/75] via 10.1.78.8, 00:12:14, Ethernet2
     10.0.0.0/24 is subnetted, 3 subnets
C 10.1.78.0 is directly connected, Ethernet2
C 10.1.67.0 is directly connected, Serial1
O IA 10.1.89.0 [110/74] via 10.1.78.8, 00:12:15, Ethernet2
     60.0.0.0/24 is subnetted, 1 subnets
O N2 60.60.60.0 [110/5] via 10.1.67.6, 00:12:16, Serial1

r6
router ospf 1
 log-adjacency-changes
 area 67 nssa
 redistribute rip metric 5 subnets <--- just added to make r6 an ASBR for
fun
 network 6.6.6.6 0.0.0.0 area 67
 network 10.1.67.6 0.0.0.0 area 67

r6#r
Gateway of last resort is 10.1.67.7 to network 0.0.0.0

O N2 99.0.0.0/8 [110/20] via 10.1.67.7, 00:13:56, Serial1
     6.0.0.0/32 is subnetted, 1 subnets
C 6.6.6.6 is directly connected, Loopback0
     7.0.0.0/24 is subnetted, 1 subnets
O IA 7.7.7.0 [110/65] via 10.1.67.7, 00:41:20, Serial1
     8.0.0.0/32 is subnetted, 1 subnets
O IA 8.8.8.8 [110/75] via 10.1.67.7, 00:41:20, Serial1
     9.0.0.0/32 is subnetted, 1 subnets
O IA 9.9.9.9 [110/139] via 10.1.67.7, 00:37:14, Serial1
     10.0.0.0/24 is subnetted, 3 subnets
O IA 10.1.78.0 [110/74] via 10.1.67.7, 00:41:21, Serial1
C 10.1.67.0 is directly connected, Serial1
O IA 10.1.89.0 [110/138] via 10.1.67.7, 00:41:21, Serial1
     60.0.0.0/24 is subnetted, 1 subnets
C 60.60.60.0 is directly connected, Loopback1
O*N2 0.0.0.0/0 [110/20] via 10.1.67.7, 00:13:42, Serial1

r6#od ns 99.0.0.0

       OSPF Router with ID (6.6.6.6) (Process ID 1)

                Type-7 AS External Link States (Area 67)

  Routing Bit Set on this LSA
  LS age: 1014
  Options: (No TOS-capability, No Type 7/5 translation, DC)
  LS Type: AS External Link
  Link State ID: 99.0.0.0 (External Network Number )
  Advertising Router: 7.7.7.7
  LS Seq Number: 80000001
  Checksum: 0x3495
  Length: 36
  Network Mask: /8
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 20
        Forward Address: 10.1.67.7
        External Route Tag: 0



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