From: Omer Ansari (omer@xxxxxxxxxx)
Date: Thu Jul 11 2002 - 13:46:07 GMT-3
Unless you add the loopback interface as a network statement into BGP.
but then you could avoid the two commands, and extra routes in the route
table by just using next-hop-self.
On Thu, 11 Jul 2002, Peter van Oene wrote:
> If RB has a loopback, it will use that as the next hop and then its not so
> nice.
>
> At 05:37 PM 7/10/2002 -0700, ccie candidate wrote:
> > i think what you did is nice ..when RB advertises 172.17.1.0 subnet to
> > RC , it will be propagated to RC with next hop of RB , so RC will be able
> > to add this network into the routing table ( because the two conditions
> > are satisfied , no sync and next hop ,)
> >as long as this subnet appears in RC routing table , the router again will
> >be able to push the 199.172.1.0 into its routing table , because no sync
> >and now the next hop is known ( 172.17.1.0 ) which is RA address .
> >
> >interesting :)
> >
> >
> >
> >--
> >
> >On Wed, 10 Jul 2002 23:53:45
> > Hunt Lee wrote:
> > >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.
> > >
> > >
> > >
> > >http://www.sold.com.au - SOLD.com.au
> > >- Find yourself a bargain!
This archive was generated by hypermail 2.1.4 : Sat Sep 07 2002 - 19:36:26 GMT-3