05-04-2012 02:22 PM - edited 03-07-2019 06:31 AM
Hi
Maybe I don't understand iBGP, becouse I think that it's a IGP, like ospf, rip, and I know that evoid full mesh I can use router reflector, so I create an network with R1, R2 and R3, with R1 how router reflector and R2 -R3 how router reflector clients. but when I try to do ping from R2 to R3 don't work, and if I do sh ip route on R2/R3 they can't learn networks. I don't know what I'm wrong. ...why I need using ospf or rip or routing static for this work? I mean, I just want to use iBGP no more, not iBGP with another IGP.
R1---Router Reflector
en
conf t
hostname REFLECTOR
int fa1/0
no sw
ip add 192.168.0.253 255.255.255.252
no sh
exi
int fa1/1
no sw
ip add 192.168.1.253 255.255.255.252
no sh
exi
no router bgp 100
router bgp 100
no sync
exit
exit
R2---Router Cliente
en
conf t
hostname CLIENTE1
int fa1/0
no sw
ip add 192.168.0.254 255.255.255.252
no sh
exi
int loopback 1
ip add 192.168.0.1 255.255.255.128
no sh
exi
ip route 192.168.0.0 255.255.255.0 null0
router bgp 100
no sync
exit
exit
R3---Router Cliente
en
conf t
hostname CLIENTE2
int fa1/0
no sw
ip add 192.168.1.254 255.255.255.252
no sh
exi
int loopback 1
ip add 192.168.1.1 255.255.255.128
no sh
exi
ip route 192.168.1.0 255.255.255.0 null0
router bgp 100
no sync
exit
exit
thanks.
05-04-2012 02:30 PM
Have a look at this doc:
http://www.informit.com/library/content.aspx?b=CCIE_Practical_Studies_II&seqNum=92
HTH
05-04-2012 03:19 PM
I dont see any neighbor or network statements under your BGP config? if you are going to use the loopback as your neighbour then you need to run an IGP routing protocol or use static route statemts between the the routers so that they will know about the loopback interface and also you need to use the next-hop self statement under your bgp config if you use the loopback as the neighbour address.
05-04-2012 03:23 PM
sorry this is my configuration, and don't work
R1---Router Reflector
en
conf t
hostname REFLECTOR
int fa1/0
no sw
ip add 192.168.0.253 255.255.255.252
no sh
exi
int fa1/1
no sw
ip add 192.168.1.253 255.255.255.252
no sh
exi
no router bgp 100
router bgp 100
no sync
neighbor 192.168.0.254 remote-as 100
neighbor 192.168.0.254 route-reflector
neighbor 192.168.1.254 remote-as 100
neighbor 192.168.1.254 router-reflector
exit
exit
R2---Router Cliente
en
conf t
hostname CLIENTE1
int fa1/0
no sw
ip add 192.168.0.254 255.255.255.252
no sh
exi
int loopback 1
ip add 192.168.0.1 255.255.255.128
no sh
exi
ip route 192.168.0.0 255.255.255.0 null0
router bgp 100
no sync
neighbor 192.168.0.253 remote-as 100
network 192.168.0.0 mask 255.255.255.0
exit
exit
R3---Router Cliente
en
conf t
hostname CLIENTE2
int fa1/0
no sw
ip add 192.168.1.254 255.255.255.252
no sh
exi
int loopback 1
ip add 192.168.1.1 255.255.255.128
no sh
exi
ip route 192.168.1.0 255.255.255.0 null0
router bgp 100
no sync
neighbor 192.168.1.253 remote-as 100
network 192.168.1.0 mask 255.255.255.0
exit
exit
05-04-2012 10:12 PM
iBGP firstly is BGP "Internal" means - BGP inside AS, not "BGP instead IGP". It is designed for routers inside AS to talk BGP directly to each other without BGP to IGP redistribution. BGP as IGP is not a good choise because of it's very silent and slow nature.
BGP is an ip routing application that allows two routers (in theory) to exchange routes not being directly connected to each other. Therefore each route has an attribute NEXT HOP which equals to peer router's IP. For a router to use a route it must have that NEXT HOP address in it's routing table. Key thing: this attribute DOES NOT CHANGE during iBGP route exchange. It only changes in eBGP peering.
So R2 sends a route to R1 with NEXT HOP of 192.168.0.254. R1 sends this route to R3 with the same NEXT HOP. But R3 does not know how to reach the 192.168.0.254 address. Therefore it can't use this route.
You may use neighbor <...> next-hop-self command on R1 to override this behavior.
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