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Community Member

Query regarding BGP

Q:--On the assumption that there is no IGP running in AS 64700 and synchronization is

OFF, which router in AS 64700 is going to advertise the route to 183.32.0.0?

A. TK2 only

B. TK5 only

C. TK2 and TK5 only

D. TK2, TK3, and TK4 only

E. TK2, TK3, TK4, and TK5

Explain the answer given by you >>>

Thanks

Mahi

7 REPLIES
Cisco Employee

Re: Query regarding BGP

Assuming there is a full iBGP mesh in 64700, which is not clear looking at the diagram, TK2 would advertise 183.32.0.0 to all iBGP peers and TK5 would advertise it to TK6. So the answer would be C.

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
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Ciudad de México, 06600
México
Silver

Re: Query regarding BGP

Hi Monhinder,

I had seen the same question in Testking 642-891 dumps and the answer is given there is E.

Given explanation is "We need to run IGP on AS 64700 to control the exit points from the AS. All routers in AS 64700will advertise the route."

But it is not clear and i personally feel it could be C only.

Since all routers in 64700 are running ibgp between them, they won't forward ibgp routes to any ibgp peer. So the ans could be TK2(ibgp) will advertise that ebgp route to other ibgp peers and tk5 will advertise the same in its ebgp session to other AS.

I really doubted that there may a mistake in the question. Simillar kind of questions are there where it is like To which router(s) in AS 64700, the route to 183.32.00 will propagate. That given answer might suit to this.(to all routers in AS 64700)

Hope this will clear your doubt

Rate if it does,

Rgs

Community Member

Re: Query regarding BGP

Hi Bala,

I think Answer will be only TK2.

Because it is mention here that no IGP is running and synchronisation is turned off.

SO TK2 will advertise the route to TK3 & Tk4. but TK4 and TK3 will not advertise the route to TK5, because ibgp will not advertise the route learned by ibgp to another ibgp.

SO TK2 will be only answer.

What will u say ????

Thanks

Mahi

Silver

Re: Query regarding BGP

Hi mohinder,

If you see the diagram they given that ibgp full mesh, so that tk2 will advertise to tk5 also just like to tk3 and tk4.

Rate if it does,

Rgs,

Community Member

Re: Query regarding BGP

Hi bala,

one more question is there...asking..

which router in AS 64700 is going to end up advertising a route to network

183.32.0.0?

Fig. is same...

Assumption is no IGP is running and synchronisation is turned off..

What do u think about it...

Silver

Re: Query regarding BGP

Hi Mohindar,

Are u sure whether the options are same for this question too...

Becz, i feel it could only TK3 and TK4 only. Since it is having only ibgp peers it won't advertise the route to network 183.32.0.0. If u take tk1 it will advertise to all other ibgp peers and tk5 will advertise it too. ebgp peer. So only tk3 and tk4 will end up advertising it to other peers.

Rate if it does,

Regards,

Community Member

Re: Query regarding BGP

Hi,

My ans is C.

In AS64700 TK2 to TK5 running IBGP & tk2 to tk1 EBGP so tk1 adv. route 182.32.0.0 to tk2 & tk2 forward to all IBGP peer.but TK5 forward to another AS because IBGP running inside AS64700 fullmesh & even with IGP not running there is reachability internal AS64700 between tk2 & tk3 & tk4 & tk5 as minimum static route.

Rate if it Does.

Thanks,

Yogesh

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