BGP............aaaaaaaaah pain here

rameeshmeshad

R1<--ebgp-->R2<--IBGP-->R3

there are some networks on R1......and iam getting ma bgp table filled on R2 and R3

problem is i cant ping the network which are even showing in the R3 s routing table.......

i cleared all the facts.......like next-hop-self on R2 and route reflector at R3......


here is the commands on R3.........

router bgp 200
no synchronization
bgp log-neighbor-changes
neighbor IBGP_PEER peer-group
neighbor IBGP_PEER remote-as 200
neighbor IBGP_PEER route-reflector-client
neighbor 1.1.1.2 peer-group IBGP_PEER
no auto-summary
R3#sh ip bgp
BGP table version is 4, local router ID is 172.30.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path
*>i172.16.1.0/24 1.1.1.2 0 100 0 100 i
*>i172.16.2.0/24 1.1.1.2 0 100 0 100 i
*>i172.16.3.0/24 1.1.1.2 0 100 0 100 i

R3#sh ip route
Codes: C - connected, S - static, 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
i - IS-IS, su - IS-IS summary, 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 not set

1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Serial2/0
172.16.0.0/24 is subnetted, 3 subnets
B 172.16.1.0 [200/0] via 1.1.1.2, 00:27:05
B 172.16.2.0 [200/0] via 1.1.1.2, 00:27:05
B 172.16.3.0 [200/0] via 1.1.1.2, 00:27:05

R3#ping 172.16.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)


ON R2

router bgp 200
no synchronization
neighbor IBGP_PEER peer-group
neighbor IBGP_PEER remote-as 200
neighbor IBGP_PEER next-hop-self
neighbor 1.1.1.1 peer-group IBGP_PEER
neighbor 2.2.2.2 remote-as 100

R2#sh ip bgp
BGP table version is 4, local router ID is 2.2.2.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path
*> 172.16.1.0/24 2.2.2.2 0 0 100 i
*> 172.16.2.0/24 2.2.2.2 0 0 100 i
*> 172.16.3.0/24 2.2.2.2 0 0 100 i

i can ping from here


whats d reason behind these ?

kalebksp

Does R1 have a route to get back to R3?

rameeshmeshad

kalebksp wrote: »

Does R1 have a route to get back to R3?

thank u all.............

i cleared it rite now.........

gav a static route on R1 to the link R2

---

R3
.............and a static route on R3 to the link R1----R2

...............................now also i didin get the idea behind this...y do i need the help of static or any other IGPS here?
y do BGP doesnt advertise the routes to its neighbours?


OMG........bulb glowed now........if we provide network commands on all BGP routers and provide the serial links..it should be ping ....na...?(going to do that rite now)

tim100

Also, you do not need the route-reflector-client command on R3

APA

Sounds like you need to do a bit of reading on the basic operation of eBGP peering and iBGP peering...

An iBGP peer will pass on routes learnt from an eBGP peer to all other neighbors.... however an iBGP peer will not by default pass on routes learnt from another iBGP peer.

Hence the route-reflector command needed for R3 or peer R3 with R1 to get a full mesh topology.

networker050184

A.P.A wrote: »

Sounds like you need to do a bit of reading on the basic operation of eBGP peering and iBGP peering...

An iBGP peer will pass on routes learnt from an eBGP peer to all other neighbors.... however an iBGP peer will not by default pass on routes learnt from another iBGP peer.

Hence the route-reflector command needed for R3 or peer R3 with R1 to get a full mesh topology.

R2 and R1 are eBGP peers so no need for the route reflector in this set up. Now if you connected another router in AS200 then you would need to peer it with R2 to get the routes or peer it with R3 and use the route reflector.

tim100

A.P.A wrote: »

Sounds like you need to do a bit of reading on the basic operation of eBGP peering and iBGP peering...

An iBGP peer will pass on routes learnt from an eBGP peer to all other neighbors.... however an iBGP peer will not by default pass on routes learnt from another iBGP peer.

Hence the route-reflector command needed for R3 or peer R3 with R1 to get a full mesh topology.

Sounds like you need to read his configuration a second time:

R1<--ebgp-->R2<--IBGP-->R3

Also, if all three routers were running IBGP it would make no sense to put the route-reflector-client command on R3 since it would only be neighboring with R2 in the first place. R2 would be neighboring with R1 and R3. You would place the route-reflector-client command on R2 in it's neighbor statements to either R1 or R3 or both. You can also simplify it with a peer-group. When you use a route-reflector-client command it makes the router the command was entered on the route reflector, not the route reflector client. I noticed in your signature you are working on the BGP exam for the CCIP. Perhaps you should do more reading on the operation of BGP before you sit that exam.

kryolla

just set up a confederation it will make things a lot easier

hehehehehe

APA

tim100 wrote: »

Sounds like you need to read his configuration a second time:

R1<--ebgp-->R2<--IBGP-->R3

Also, if all three routers were running IBGP it would make no sense to put the route-reflector-client command on R3 since it would only be neighboring with R2 in the first place. R2 would be neighboring with R1 and R3. You would place the route-reflector-client command on R2 in it's neighbor statements to either R1 or R3 or both. You can also simplify it with a peer-group. When you use a route-reflector-client command it makes the router the command was entered on the route reflector, not the route reflector client. I noticed in your signature you are working on the BGP exam for the CCIP. Perhaps you should do more reading on the operation of BGP before you sit that exam.

oh brother....

Maybe I just need to stop explaining things from my point of view where I understand it completely....

When you use a route-reflector-client command it makes the router the command was entered on the route reflector, not the route reflector client

I was actually implying the route-reflector client statement could be used on R2 for the neighbor statement of R3... that's common sense...... so I agree with you on how to use the route reflector...........but now I'm totally awake and I look at the topology again I realise that as you previously said the RR entry is not needed.

Thanks for the wake up call

Also, if all three routers were running IBGP it would make no sense to put the route-reflector-client command on R3 since it would only be neighboring with R2 in the first place. R2 would be neighboring with R1 and R3.

Could you explain your theory for this? If they were all running iBGP(not full mesh) and you didn't have the route-reflector command.... therefore R1<-iBGP->R2<-iBGP->R3

How would R1 and R3 learn each others routes without peering up???? Peering up with R2 alone would not allow this without the route-relector correct.....? AS R2 wouldn't pass on routes learnt via on iBGP peer to another iBGP peer....

I noticed in your signature you are working on the BGP exam for the CCIP. Perhaps you should do more reading on the operation of BGP before you sit that exam.

Yeah good observation, being on these forums helps nut out the areas I am a bit rusty on as well...... You can always improve yourself..... No matter what title you have....

APA

networker050184 wrote: »

R2 and R1 are eBGP peers so no need for the route reflector in this set up. Now if you connected another router in AS200 then you would need to peer it with R2 to get the routes or peer it with R3 and use the route reflector.

Yep totally agree now

I need to stop replying to posts after a heavy gym workout!!

tim100

A.P.A wrote: »

Could you explain your theory for this? If they were all running iBGP(not full mesh) and you didn't have the route-reflector command.... therefore R1<-iBGP->R2<-iBGP->R3

How would R1 and R3 learn each others routes without peering up???? Peering up with R2 alone would not allow this without the route-relector correct.....? AS R2 wouldn't pass on routes learnt via on iBGP peer to another iBGP peer....

As I stated in the original post, R2 would be configured with the route-reflector-client command in it's neighbor statements to either R1 or R3 or both. It wouldn't be configured on R3.

APA

tim100 wrote: »

As I stated in the original post, R2 would be configured with the route-reflector-client command in it's neighbor statements to either R1 or R3 or both. It wouldn't be configured on R3.

So then we do agree if it was a full iBGP topology, that you do need the route-reflector statement for R3... but it's to be configured on R2...

My original post stated RR 'for' R3 not 'on' R3... as you would be configuring the 'neighbor x.x.x.x route-reflector-client' on R2. (Where x.x.x.x = either R1's or R3's address) <---- Again this was assuming it is an iBGP topology only, no eBGP involved.