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Need help getting NSSA ABR to flood default from NSSA ASBR

I am having trouble advertising a default route from an NSSA ASBR to the ABR, and then subsequently getting the NSSA ABR to propagate that default route to the OSPF domain. The NSSA is connect to area 0 w/ a virtual link. I have tried different versions of routers/code to no avail. The farthest I have been able to get is configuring area x nssa default-information originate along w/ a static default route on the NSSA ASBR. Sometimes the NSSA ABR will show an N2 in the routing table. It would appear the the P-bit is not set because the default route never gets propagated. I'm able to get the external default route propagated if I connect it to an ABR directly.

5 REPLIES
Bronze

Re: Need help getting NSSA ABR to flood default from NSSA ASBR

Have you also included the "default-information-originate" in the area nssa command of the NSSA ABR, as well as the NSSA ASBR?

Also, I'm not sure why the ABR will only show the N2 sometimes. Is the route also going down in the ASBR at the same time it goes down in the ABR? Does the Type 7 LSA come and go from the OSPF database?

HTH

Mark

Cisco Employee

Re: Need help getting NSSA ABR to flood default from NSSA ASBR

This should work. The only problem I can think of is the virtual link not being established properly.

Couls you provide us with the following for the NSSA ABR:

sh ip ospf virt

sh ip ospf da nssa

sh ip ospf da ext

sh ip ospf

Thanks,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Anonymous
N/A

Re: Need help getting NSSA ABR to flood default from NSSA ASBR

Router r5 is the NSSA ABR for area 5, and R6 is the NSSA ASBR for area 6. Here are the routing tables for R5 and R6 as well as the output you requested.

r5#r ho show 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, * - candidate default

U - per-user static route, o - ODR

T - traffic engineered route

Gateway of last resort is 10.5.1.2 to network 0.0.0.0

10.0.0.0/8 is variably subnetted, 10 subnets, 4 masks

O 10.0.10.0/24 [110/65] via 10.3.1.9, 00:25:42, Serial0

C 10.3.1.8/29 is directly connected, Serial0

O 10.3.1.9/32 [110/64] via 10.3.1.9, 3d02h, Serial0

O IA 10.2.10.0/24 [110/138] via 10.3.1.9, 00:25:42, Serial0

O 10.3.1.10/32 [110/128] via 10.3.1.9, 3d02h, Serial0

O IA 10.4.10.0/24 [110/138] via 10.3.1.9, 00:25:42, Serial0

O 10.3.1.0/30 [110/128] via 10.3.1.9, 3d02h, Serial0

C 10.5.1.0/30 is directly connected, ATM0

O IA 10.6.1.24/29 [110/129] via 10.3.1.9, 00:22:51, Serial0

C 10.1.254.4/32 is directly connected, Loopback0

O*N2 0.0.0.0/0 [110/1] via 10.5.1.2, 00:04:08, ATM0

r5#

r6#show 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 172.16.1.2 to network 0.0.0.0

172.16.0.0/24 is subnetted, 1 subnets

C 172.16.1.0 is directly connected, Ethernet0

10.0.0.0/8 is variably subnetted, 7 subnets, 5 masks

O IA 10.0.10.0/24 [110/130] via 10.5.1.1, 00:26:10, ATM0

O IA 10.2.10.0/24 [110/203] via 10.5.1.1, 3d04h, ATM0

O IA 10.4.10.0/24 [110/203] via 10.5.1.1, 3d03h, ATM0

O IA 10.3.0.0/16 [110/193] via 10.5.1.1, 3d04h, ATM0

C 10.5.1.0/30 is directly connected, ATM0

O IA 10.6.1.24/29 [110/194] via 10.5.1.1, 00:23:15, ATM0

C 10.1.254.5/32 is directly connected, Loopback0

S* 0.0.0.0/0 [1/0] via 172.16.1.2

r6#

r6#show ip ospf virt

r6#show ip ospf da nssa

OSPF Router with ID (10.1.254.5) (Process ID 1)

Type-7 AS External Link States (Area 5)

LS age: 1496

Options: (No TOS-capability, No Type 7/5 translation, DC)

LS Type: AS External Link

Link State ID: 0.0.0.0 (External Network Number )

Advertising Router: 10.1.254.4

LS Seq Number: 80000090

Checksum: 0x7A99

Length: 36

Network Mask: /0

Metric Type: 2 (Larger than any link state path)

TOS: 0

Metric: 1

Forward Address: 0.0.0.0

External Route Tag: 0

--More-- LS age: 1617

Options: (No TOS-capability, Type 7/5 translation, DC)

LS Type: AS External Link

Link State ID: 0.0.0.0 (External Network Number )

Advertising Router: 10.1.254.5

LS Seq Number: 80000001

Checksum: 0x1B7F

Length: 36

Network Mask: /0

Metric Type: 2 (Larger than any link state path)

TOS: 0

Metric: 1

Forward Address: 0.0.0.0

External Route Tag: 0

r6#show ip ospf da nssa ext

OSPF Router with ID (10.1.254.5) (Process ID 1)

r6#show ip ospf

Routing Process "ospf 1" with ID 10.1.254.5

Supports only single TOS(TOS0) routes

Supports opaque LSA

It is an autonomous system boundary router

Redistributing External Routes from,

SPF schedule delay 5 secs, Hold time between two SPFs 10 secs

Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs

Number of external LSA 0. Checksum Sum 0x0

Number of opaque AS LSA 0. Checksum Sum 0x0

Number of DCbitless external and opaque AS LSA 0

Number of DoNotAge external and opaque AS LSA 0

Number of areas in this router is 1. 0 normal 0 stub 1 nssa

External flood list length 0

Area 5

Number of interfaces in this area is 1

It is a NSSA area

generates NSSA default route with cost 1

Area has no authentication

SPF algorithm executed 46 times

Area ranges are

Number of LSA 10. Checksum Sum 0x60734

Number of opaque link LSA 0. Checksum Sum 0x0

Number of DCbitless LSA 0

--More-- Number of indication LSA 0

Number of DoNotAge LSA 0

Flood list length 0

T_SERV#5

[Resuming connection 2 to r5 ... ]

r5#show ip ospf virt

Virtual Link OSPF_VL0 to router 10.1.254.1 is up

Run as demand circuit

DoNotAge LSA allowed.

Transit area 3, via interface Serial0, Cost of using 64

Transmit Delay is 1 sec, State POINT_TO_POINT,

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Hello due in 00:00:00

Adjacency State FULL (Hello suppressed)

Message digest authentication enabled

No key configured, using default key id 0

r5#show ip ospf da nssa

OSPF Router with ID (10.1.254.4) (Process ID 1)

Type-7 AS External Link States (Area 5)

LS age: 1572

Options: (No TOS-capability, No Type 7/5 translation, DC)

LS Type: AS External Link

Link State ID: 0.0.0.0 (External Network Number )

Advertising Router: 10.1.254.4

LS Seq Number: 80000090

Checksum: 0x7A99

Length: 36

Network Mask: /0

Metric Type: 2 (Larger than any link state path)

TOS: 0

Metric: 1

Forward Address: 0.0.0.0

External Route Tag: 0

--More-- Routing Bit Set on this LSA

LS age: 1695

Options: (No TOS-capability, Type 7/5 translation, DC)

LS Type: AS External Link

Link State ID: 0.0.0.0 (External Network Number )

Advertising Router: 10.1.254.5

LS Seq Number: 80000001

Checksum: 0x1B7F

Length: 36

Network Mask: /0

Metric Type: 2 (Larger than any link state path)

TOS: 0

Metric: 1

Forward Address: 0.0.0.0

External Route Tag: 0

r5#show ip osp f da ext

OSPF Router with ID (10.1.254.4) (Process ID 1)

r5#show ip ospf

Routing Process "ospf 1" with ID 10.1.254.4

Supports only single TOS(TOS0) routes

It is an area border router

SPF schedule delay 5 secs, Hold time between two SPFs 10 secs

Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs

Number of external LSA 0. Checksum Sum 0x0

Number of DCbitless external LSA 0

Number of DoNotAge external LSA 0

Number of areas in this router is 3. 2 normal 0 stub 1 nssa

Area BACKBONE(0)

Number of interfaces in this area is 1

Area has message digest authentication

SPF algorithm executed 38 times

Area ranges are

Number of LSA 17. Checksum Sum 0x69E54

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 13

Area 3

Number of interfaces in this area is 1

Area has message digest authentication

SPF algorithm executed 32 times

Area ranges are

--More-- 10.3.0.0/16 Active(128) Advertise

Number of LSA 27. Checksum Sum 0xBAECF

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 0

Area 5

Number of interfaces in this area is 1

It is a NSSA area

Perform type-7/type-5 LSA translation

generates NSSA default route with cost 1

Area has no authentication

SPF algorithm executed 56 times

Area ranges are

Number of LSA 16. Checksum Sum 0x97857

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 0

r5#

Cisco Employee

Re: Need help getting NSSA ABR to flood default from NSSA ASBR

Both R5 and R6 are advertising a type 7 LSA. From what I understand R6 is the ASBR and only it should be advertising the type 7. Could you post the ospf config for R5.

BTW: Can you see any of the routes from area 5 in area 0 and the rest of the AS?

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Anonymous
N/A

Re: Need help getting NSSA ABR to flood default from NSSA ASBR

I figured it out...must be bug related. I am studying for the RS IE, and am using older 3810s. Once I replaced the configuration w/ 2600 and 3600 routers, it worked.

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