From: Brian McGahan (brian@cyscoexpert.com)
Date: Sat Jul 05 2003 - 17:55:20 GMT-3
Scott,
I think you're misinterpreting what I'm saying. You can use a
default route to establish BGP peering, as long as both sides are not
using a default.
HTH
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
Toll Free: 866.CyscoXP
Fax: 847.674.2625
> -----Original Message-----
> From: Scott Morris [mailto:swm@emanon.com]
> Sent: Friday, July 04, 2003 3:03 PM
> To: 'Brian McGahan'; 'Donny MATEO'; 'Volkov, Dmitry (IDS Canada)'
> Cc: ccielab@groupstudy.com; nobody@groupstudy.com
> Subject: RE: BGP peer establishment
>
> Correct. Any prefix longer than /0 would count as a "non-default"
> route. :)
>
> Thanks for the output though!
>
> Scott
>
> -----Original Message-----
> From: Brian McGahan [mailto:brian@cyscoexpert.com]
> Sent: Friday, July 04, 2003 2:18 PM
> To: 'Scott Morris'; 'Donny MATEO'; 'Volkov, Dmitry (IDS Canada)'
> Cc: ccielab@groupstudy.com; nobody@groupstudy.com
> Subject: RE: BGP peer establishment
>
>
> Not necessarily. As long as one side of the connection has a
> longer match than 0.0.0.0/0 adjacency can be established. Take the
> following scenario:
>
> R1-16.0.0.0/8---R6---26.0.0.0/8---R2
>
> R1 is in AS 1, R2 is in AS 2. They are transitting R6 to peer.
> The only route that R1 has to the 26.0.0.0/8 subnet is a default,
while
> R2 has a longer match to 16.0.0.0/8.
>
> R1#sh run | b router bgp
> router bgp 1
> bgp log-neighbor-changes
> network 1.1.1.1 mask 255.255.255.255
> neighbor 26.0.0.2 remote-as 2
> neighbor 26.0.0.2 ebgp-multihop 255
> !
> ip route 0.0.0.0 0.0.0.0 16.0.0.6
>
> R2#sh run | b router bgp
> router bgp 2
> bgp log-neighbor-changes
> network 2.2.2.2 mask 255.255.255.255
> neighbor 16.0.0.1 remote-as 1
> neighbor 16.0.0.1 ebgp-multihop 255
> !
> ip route 16.0.0.0 255.0.0.0 26.0.0.6
>
> R1#sh ip bgp sum | b Neighbor
> Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down
> State/PfxRcd
> 26.0.0.2 4 2 11 11 3 0 0 00:06:32
> 1
>
> R2#sh ip bgp sum | b Neighbor
> Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down
> State/PfxRcd
> 16.0.0.1 4 1 12 12 3 0 0 00:07:10
> 1
>
> R1#sh ip bgp
> BGP table version is 3, local router ID is 16.0.0.1
> 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
> *> 1.1.1.1/32 0.0.0.0 0 32768 i
> *> 2.2.2.2/32 26.0.0.2 0 0 2 i
>
> R2#sh ip bgp
> BGP table version is 3, local router ID is 26.0.0.2
> 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
> *> 1.1.1.1/32 16.0.0.1 0 0 1 i
> *> 2.2.2.2/32 0.0.0.0 0 32768 i
>
> R1#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 16.0.0.6 to network 0.0.0.0
>
> C 16.0.0.0/8 is directly connected, FastEthernet0/6
> 1.0.0.0/32 is subnetted, 1 subnets
> C 1.1.1.1 is directly connected, Loopback0
> 2.0.0.0/32 is subnetted, 1 subnets
> B 2.2.2.2 [20/0] via 26.0.0.2, 00:06:08
> S* 0.0.0.0/0 [1/0] via 16.0.0.6
> R1#
>
> R2#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
>
> S 16.0.0.0/8 [1/0] via 26.0.0.6
> 1.0.0.0/32 is subnetted, 1 subnets
> B 1.1.1.1 [20/0] via 16.0.0.1, 00:06:55
> 2.0.0.0/32 is subnetted, 1 subnets
> C 2.2.2.2 is directly connected, Loopback0
> C 26.0.0.0/8 is directly connected, FastEthernet0/6
>
>
> As you can see from the above output, as long as one side has a
> longer match than 0, BGP adjacency can be established.
>
> HTH,
>
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@cyscoexpert.com
>
> CyscoExpert Corporation
> Internetwork Consulting & Training
> Toll Free: 866.CyscoXP
> Fax: 847.674.2625
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > Scott Morris
> > Sent: Friday, July 04, 2003 8:57 AM
> > To: 'Donny MATEO'; 'Volkov, Dmitry (IDS Canada)'
> > Cc: ccielab@groupstudy.com; nobody@groupstudy.com
> > Subject: RE: BGP peer establishment
> >
> > There must be a non-default route to reach the other side. So
> anything
> > other than a 0/0 route will work.
> >
> > Scott
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > Donny MATEO
> > Sent: Friday, July 04, 2003 1:58 AM
> > To: Volkov, Dmitry (IDS Canada)
> > Cc: 'ccielab@groupstudy.com'; nobody@groupstudy.com
> > Subject: Re: BGP peer establishment
> >
> >
> > If I remember correctly there was an old thread discussing this. The
> > conclusion is something like BGP need specific route to establish
> > peering. Not sure if there is anymore information as to why and so
on.
> >
> > Donny
> >
> >
> >
> >
> >
> > "Volkov, Dmitry
> >
> > (IDS Canada)" To:
> > "'ccielab@groupstudy.com'" <ccielab@groupstudy.com>
> >
> > <dmitry_volkov@ca cc:
> >
> > .ml.com> Subject: BGP peer
> > establishment
> > Sent by:
> >
> > nobody@groupstudy
> >
> > .com
> >
> >
> >
> >
> >
> > 07/04/2003 06:22
> >
> > AM
> >
> > Please respond to
> >
> > "Volkov, Dmitry
> >
> > (IDS Canada)"
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > R5(172.50.50.5)---------(.1)pix(.10)--------(172.50.10.1)R1
> >
> > R5 can ping R1; R5 uses default route to reach R1. R5 can not
> establish
> > BGP peering with R1 until I put static route - more specific than
> > 0.0.0.0 0.0.0.0 - WHY ?
> >
> > r5#sh ip bgp sum
> > BGP router identifier 60.5.5.5, local AS number 55
> > BGP table version is 1, main routing table version 1
> >
> > Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down
> > State/PfxRcd
> > 172.50.10.1 4 65 0 0 0 0 0 never
> > Active
> >
> > r5#sh ip ro
> > <snip>
> > R* 0.0.0.0/0 [120/1] via 172.50.50.1, 00:00:06, FastEthernet0/0
> >
> > r5#conf t
> > Enter configuration commands, one per line. End with CNTL/Z.
> > r5(config)#ip route 172.50.10.1 255.255.255.255 172.50.50.1
> >
> > 00:55:02: %BGP-5-ADJCHANGE: neighbor 172.50.10.1 Up bgp ev
> >
> > r5#sh ip bgp sum
> > BGP router identifier 60.5.5.5, local AS number 55
> > BGP table version is 1, main routing table version 1
> >
> > Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down
> > State/PfxRcd
> > 172.50.10.1 4 65 5 5 1 0 0 00:02:01
> > 0
> > r5# sh ip ro
> > <snip>
> >
> > S 172.50.10.1/32 [1/0] via 172.50.50.1
> > R* 0.0.0.0/0 [120/1] via 172.50.50.1, 00:00:13, FastEthernet0/0
> >
> > r5#
> > router bgp 55
> > bgp log-neighbor-changes
> > neighbor 172.50.10.1 remote-as 65
> > neighbor 172.50.10.1 ebgp-multihop 2
> > r1#
> > router bgp 65
> > bgp log-neighbor-changes
> > neighbor 172.50.50.5 remote-as 55
> > neighbor 172.50.50.5 ebgp-multihop 2
> >
> > Thank You,
> >
> > Dmitry Volkov
> > CCIE # 10292
> >
> >
> >
>
This archive was generated by hypermail 2.1.4 : Wed Aug 06 2003 - 06:52:25 GMT-3