Hi Group, 199.172.1.0 / 24 --- RTA --- RTB --- RTC
RTA's interface - 172.17.1.2 (connecting to RTB) RTB's interface - 172.17.1.1 (connecting to RTA) RTB's interface - 10.1.1.1 (connecting to RTC) RTC's interface - 10.1.1.2 (connecting to RTB) RTA is in AS 1 RTB & RTC are both in AS 2 I understand that for a router to learn and install an IBGP route from an IBGP neighbor, it will need either "no sync" command or learnt via any IGP. But for the BGP route's next-hop reachability, I have searched on Cisco books & CCO website, but they only said either advertised the next-hop to the IBGP router (in this case, RTC) with IGP routes, or use "next-hop-self" command (on RTB). However, I found that if I advertise the next-hop reachability (the 172.17.1.0/24 subent) via BGP's network command, it would also work. Is this ok to use?? Is there any gotcha on this?? I just thought it is pretty handy to just use BGP, without relying on any IGP. RouterB#sh ip bgp BGP table version is 4, local router ID is 192.168.0.1 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 *> 10.1.1.0/30 0.0.0.0 0 32768 i *> 172.17.1.0/24 0.0.0.0 0 32768 i *> 199.172.1.0 172.17.1.2 0 0 1 i RouterB#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 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 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, 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 172.17.0.0/24 is subnetted, 1 subnets C 172.17.1.0 is directly connected, Ethernet0 10.0.0.0/30 is subnetted, 1 subnets C 10.1.1.0 is directly connected, Serial0 B 199.172.1.0/24 [20/0] via 172.17.1.2, 01:34:38 C 192.168.0.0/24 is directly connected, Loopback0 RouterB# And at RTC, it would be able to reach 199.172.1.0 /24 via next hop of 172.17.1.2, which in turn is reached via 10.1.1.1. RouterC#sh ip bgp BGP table version is 4, local router ID is 172.16.3.1 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 *>i10.1.1.0/30 10.1.1.1 0 100 0 i *>i172.17.1.0/24 10.1.1.1 0 100 0 i *>i199.172.1.0 172.17.1.2 0 100 0 1 i 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 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 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, o - ODR Gateway of last resort is not set 172.17.0.0/24 is subnetted, 1 subnets B 172.17.1.0 [200/0] via 10.1.1.1, 00:26:57 172.16.0.0/24 is subnetted, 2 subnets C 172.16.2.0 is directly connected, Loopback1 C 172.16.3.0 is directly connected, Loopback0 10.0.0.0/30 is subnetted, 1 subnets C 10.1.1.0 is directly connected, Serial0 B 199.172.1.0/24 [200/0] via 172.17.1.2, 00:25:57 RouterC# Any ideas will be greatly appreciated. Thanks!!! H. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=48761&t=48761 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]