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Community Member

OSPF area question

Hi Cisco Experts,

I would appreciate it if somebody could confirm if I am correct in what I say here.

I have Area0 which is connected to Area1 and Area2. Area1 and Area2 are not connected to each other.

- Area1 has two ABRs to Area0, abr_A & abr_B - these ABRs are not L3 connected to each other.

- Area2 has one ABR to Area0.

An O (intra-area Type 1 LSA) link from Area 2 is sent into Area0 as an IA link (inter-area Type 3 LSA).

Area0 then propagates this IA link into Area1.

My question is, when the Area0 abr2 propages the IA link (which came from Area2) into Area1 - is it correct to say that Area1 would not propagate this IA link back into Area0 via abr1?

Basically, is it true that when a Type 3 is sent from Area0 into area x - if area x has two ABRs. The other ABR will not then re-send the Type 3 back into Area0.

Thanks!

Al

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: OSPF area question

Alan,

This is correct. The ABR ignores any LSA type 3 received from a non backbone area.

Regards

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
1 REPLY
Cisco Employee

Re: OSPF area question

Alan,

This is correct. The ABR ignores any LSA type 3 received from a non backbone area.

Regards

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
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