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Webcast-Catalyst9k
New Member

ospf DR and BDR

hallo, I have some questions about ospf not cleared by other docs.

In a LAN segment, inside an ospf area 0, we have a DR and BDR.

1) If the DR goes down the BDR become DR ?

2) If the DR return back up it will be always the DR ?

3) if DR goes down and BDR become DR, a new BDR will be elected ?

4) the routers that aren't DR or BDR have in the adjacensy database only DR and BDR, or all the other routers in the lan ?

best regards

francesco

3 REPLIES

Re: ospf DR and BDR

Hi

yes u r right when the DR goes down BDR will become DR and new BDR is elected.

not sure of u r 2&3 question.

Yes all the routers in a broadcast multiaccess network all the routers are going to have adjacency with DR and BDR instead of having adjacency with evry router.this is to prevent flooding of LSA's

Thanks

Mahmood

Cisco Employee

Re: ospf DR and BDR

1) BDR becomes DR indeed.

2) current DR remains DR for sake of stability.

3) A new BDR is indeed elected

4) correct

Hope this helps,

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
New Member

Re: ospf DR and BDR

Hi,

1&3. yes BDR will become DR and new BDR will be elected.

2. when DR returns active current DR still remains as DR.

4. Non DR/BDR will have adjacency with DR/BDR in that lan segment(broadcast domain)

HTH

Regards,

Rajesh

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