Exam 300-410 topic 1 question 37 discussion

I also confirmed solution "C" in the lab (CML). RR = R4 (it's clients = R1, R5, R8) and RR = R5 (it's client R2). R2's loopback has not been advertised to R4 and R8 (and vica versa) until R2 became the client of RR R5. In my lab, full reachability was achieved with R4 and R5 being RRs. (Maybe I am missing something as others stated that R4 would be enough as RR.)

C - confirmed in the lab. All that is needed is R4 to be a RR with R1 as its client and that gets all loopbacks in routers BGP tables. So having R2, R5 and R4 also works. R4 and R5 is the only option that works without any other RR configuration. So the answers assume we roll back the engineers config and take a fresh start. Definitely C.

C is correct

C works for R4, but not R5. Route reflects have to have a route to the destination to reflect it. They will only have a route when they are connected to the ebgp router (R2 & R4). After this the route will show *i in the show ibgp table and not forward. Poor design but the answer is A. C wouldn't be any different than the current setup that is more than one hop away.

Another fine example of Cisco getting you to choose the best option. Off the bat, you can eliminate A & B, since RR on an edge router (R1) is not recommended. We already know, from the question that D won't work. C is the best answer from the options provided.

There is no difference between the setup of R2 & R5 and R4 & R5. So the same problem would exist with C. R1 R4 (A) would be better but it would still be a poor design. Based on the diagram the best answer would be R2 & R4.

I think the answer is C too. If R5 and R2 have the same cluster-id, then R8 loopback coming from R5 will never be advertised to R1 because it will be discarded by R2. The real interesting question here is WHY do we have a question like this ? Multiple route reflectors topic is excluded in the exam topics.. And why don't they say that the cluster-id is the same ? Poor cisco question as always. Makes me want to dump more.

Hello, I made some tests with GNS3 and it seems A,C and D are good solutions since all loopback interfaces are reachable. But answer D is excluded by the exercise and R1 is better not to use as RR. So the only answer remaining is C. Studybuddy is correct when he says only R4 is enough but if you make R1 as client, R2 is not reachable. The right thing to do is set R4 as RR and set R5 and R8 as RR client. I hope it may help.

Just R4 as RR with R1, R5, and R8 as clients would work, but is not an option. Options C and D both work, but C seems more likely to be what they want.

R2: interface FastEthernet0/0 ip address 192.168.2.2 255.255.255.0 duplex half ! interface FastEthernet1/0 ip address 192.168.5.2 255.255.255.0 duplex half ! router bgp 400 bgp log-neighbor-changes network 192.168.2.0 network 192.168.5.0 neighbor 192.168.2.1 remote-as 400 neighbor 192.168.5.5 remote-as 400 neighbor 192.168.5.5 route-reflector-client R4: interface FastEthernet0/0 ip address 192.168.1.4 255.255.255.0 duplex half ! interface FastEthernet1/0 ip address 192.168.4.4 255.255.255.0 duplex half ! interface FastEthernet2/0 ip address 192.168.10.4 255.255.255.0 duplex half ! router bgp 400 bgp log-neighbor-changes network 192.168.1.0 network 192.168.4.0 network 192.168.10.0 neighbor 192.168.1.1 remote-as 400 neighbor 192.168.4.8 remote-as 400 neighbor 192.168.4.8 route-reflector-client neighbor 192.168.10.5 remote-as 400 R2 &R4 are working perfectly fine

Why can't RR2 send routes received from RR5 to R1?

A poorly worded and considered example. but i would settle for C. R4 has to be a RR

I really dont understand why R2 and R5 as RR don't work.

It is not a good practice to have an edge router as RR

It more sense configure reflectors on R1 and R5