Because RouterB doesn't know how to get back to RouterC. I bet if you look on RouterB's routing table you will not see an entry for the 172.17.1.0 network.
Try adding the command "network 172.17.1.0 mask 255.255.255.0" on RouterC's BGP to advertise that subnet. >>>Brian ""Hunt Lee"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hi group, > > > RotuerC ----------------- RouterA ---------------- RouterB > > On p9 of BGP 4 Command & Configuration Handbook (by Parkhurst), I follow the > exercise on Aggregating the BGP Learning Routes, everything seems well > except I can't ping from Router C to any of the 4 Loopback Interfaces I > created on Router B, even though I can see the routes fine on both Router > C's BGP table and Routing Table: > > RouterC>sh ip bgp > BGP table version is 6, local router ID is 172.17.1.2 > 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 > *> 172.16.0.0/24 172.17.1.1 0 1 2 i > *> 172.16.0.0/22 172.17.1.1 0 1 i > *> 172.16.1.0/24 172.17.1.1 0 1 2 i > *> 172.16.2.0/24 172.17.1.1 0 1 2 i > *> 172.16.3.0/24 172.17.1.1 0 1 2 i > RouterC> > > > RouterC>sh ip route > Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP > D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area > E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP > i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate > default > U - per-user static route > > Gateway of last resort is not set > > 172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks > B 172.16.0.0/22 [20/0] via 172.17.1.1, 00:00:55 > B 172.16.0.0/24 [20/0] via 172.17.1.1, 02:19:56 > B 172.16.1.0/24 [20/0] via 172.17.1.1, 02:19:56 > B 172.16.2.0/24 [20/0] via 172.17.1.1, 02:19:56 > B 172.16.3.0/24 [20/0] via 172.17.1.1, 02:19:56 > 172.17.0.0/24 is subnetted, 1 subnets > C 172.17.1.0 is directly connected, Serial0 > RouterC> > > > When I tried to do a trace to say 172.16.0.1 (which is one of the loopback > interface created on Router B), the packets was stuck on Router A > > RouterC>trace 172.16.0.1 > > Type escape sequence to abort. > Tracing the route to 172.16.0.1 > > 1 RouterA (172.17.1.1) 16 msec 16 msec 20 msec > 2 * * * > 3 > > However, on Router A, I can ping fine to all 4 loopback interfaces > advertised by Router B:- > > RouterA#ping 172.16.0.1 > > Type escape sequence to abort. > Sending 5, 100-byte ICMP Echos to 172.16.0.1, timeout is 2 seconds: > !!!!! > Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/32 ms > RouterA#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 100 percent (5/5), round-trip min/avg/max = 32/32/32 ms > RouterA#ping 172.16.2.1 > > Type escape sequence to abort. > Sending 5, 100-byte ICMP Echos to 172.16.2.1, timeout is 2 seconds: > !!!!! > Success rate is 100 percent (5/5), round-trip min/avg/max = 28/54/148 ms > RouterA# > > So if Router A can get to the Loopback interfaces advertised by Router B, > and Router C have got the routes in the Routing Table, why can't Router C > trace or ping to Router B's Loopback interfaces?? > > Please find attached a copy of the configs for the 3 routers:- > > > RouterC#sh run > Building configuration... > > Current configuration: > ! > version 11.1 > service timestamps debug datetime msec show-timezone > service timestamps log datetime msec show-timezone > service udp-small-servers > service tcp-small-servers > ! > hostname RouterC > ! > enable secret 5 $1$R1vV$Ld5F0ueggoSyb4z/goBGF. > ! > ! > interface Ethernet0 > no ip address > ! > interface Serial0 > ip address 172.17.1.2 255.255.255.0 > ! > interface Serial1 > no ip address > ! > router bgp 65530 > neighbor 172.17.1.1 remote-as 1 > ! > ip host RouterA 172.17.1.1 > ip classless > logging buffered > ! > line con 0 > line aux 0 > line vty 0 4 > password cisco > login > ! > end > > RouterC# > > -------------------------------------------------------------------------- -- > --------------------------------------------------------- > RouterA#sh run > Building configuration... > > Current configuration : 907 bytes > ! > version 12.2 > no service single-slot-reload-enable > service timestamps debug uptime > service timestamps log uptime > no service password-encryption > ! > hostname RouterA > ! > logging rate-limit console 10 except errors > enable secret 5 $1$hCDv$aQ/xa.CZ7YloCaNRpAaI90 > ! > ip subnet-zero > no ip finger > no ip domain-lookup > ip host RouterC 172.17.1.2 > ip host RouterB 10.1.1.2 > ! > no ip dhcp-client network-discovery > ! > ! > ! > ! > interface Ethernet0 > no ip address > ! > interface Serial0 > ip address 172.17.1.1 255.255.255.0 > clockrate 64000 > ! > interface Serial1 > ip address 10.1.1.1 255.255.255.252 > clockrate 64000 > ! > router bgp 1 > bgp log-neighbor-changes > aggregate-address 172.16.0.0 255.255.252.0 > neighbor 10.1.1.2 remote-as 2 > neighbor 172.17.1.2 remote-as 65530 > ! > ip kerberos source-interface any > ip classless > ip http server > ! > ! > ! > line con 0 > transport input none > line 1 16 > line aux 0 > line vty 0 4 > password cisco > login > ! > end > > RouterA# > > -------------------------------------------------------------------------- -- > --------------------------------------------------------------- > RouterB#sh run > Building configuration... > > Current configuration: > ! > version 12.0 > service timestamps debug uptime > service timestamps log uptime > no service password-encryption > ! > hostname RouterB > ! > enable secret 5 $1$zNVg$hD/CjofG0d4SosB6/7.1I1 > ! > ip subnet-zero > no ip domain-lookup > ip host RouterA 10.1.1.1 > ! > ! > ! > interface Loopback0 > ip address 172.16.0.1 255.255.255.0 > ip directed-broadcast > ! > interface Loopback1 > ip address 172.16.1.1 255.255.255.0 > ip directed-broadcast > ! > interface Loopback2 > ip address 172.16.2.1 255.255.255.0 > ip directed-broadcast > ! > interface Loopback3 > ip address 172.16.3.1 255.255.255.0 > ip directed-broadcast > ! > interface Ethernet0 > no ip address > no ip directed-broadcast > ! > interface Serial0 > ip address 10.1.1.2 255.255.255.252 > ip directed-broadcast > ! > interface Serial1 > no ip address > no ip directed-broadcast > ! > interface BRI0 > no ip address > no ip directed-broadcast > ! > router bgp 2 > network 172.16.0.0 mask 255.255.255.0 > network 172.16.1.0 mask 255.255.255.0 > network 172.16.2.0 mask 255.255.255.0 > network 172.16.3.0 mask 255.255.255.0 > neighbor 10.1.1.1 remote-as 1 > no auto-summary > ! > ip classless > ! > ! > line con 0 > transport input none > line aux 0 > line vty 0 4 > password cisco > login > ! > end > > RouterB# > > > > Thanks in advance, > > Hunt Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=46215&t=46131 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
