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Hi Guys,
I need some assistance with a problem re BGP on my international gateway routers. What is happening is that I am advertising on both routers a summary address and specific addresses to provide load sharing of traffic between the two links. The problem is with the 202.4.48.0/22 address which is advertised over the router connected to Newskies. It is showing the the next hop as the router 202.4.32.242 but not as 0.0.0.0. I have announced the specific route but can anyone can help me if out why the bgp table is showing is below.
*> 202.4.48.0/22 202.4.32.242 100 32768 i
GP table version is 21093, local router ID is 192.168.100.2 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 * 61.88.170.100/30 210.5.248.249 0 0 23649 i * 63.100.216.0/21 210.5.248.249 0 0 23649 i * 202.0.50.0 210.5.248.249 1 0 23649 i * 202.1.164.0 210.5.248.249 1 0 23649 i * 202.2.96.0/22 210.5.248.249 1 0 23649 i *> 202.4.32.0/21 0.0.0.0 0 32768 i *> 202.4.32.0/19 0.0.0.0 32768 i * i 192.168.100.1 100 0 i *> 202.4.48.0/22 202.4.32.242 100 32768 i * 210.5.248.0/21 210.5.248.249 0 0 23649 i
LAV-Newskies#sh ip bgp summary BGP router identifier 192.168.100.2, local AS number 17993 BGP table version is 21141, main routing table version 21141 9 network entries and 10 paths using 1273 bytes of memory 6 BGP path attribute entries using 720 bytes of memory 5 BGP AS-PATH entries using 168 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 8 BGP filter-list cache entries using 96 bytes of memory BGP activity 13/346 prefixes, 19/9 paths, scan interval 15 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 192.168.100.1 4 17993 3519 3520 21141 0 0 2d10h 1 210.5.248.249 4 23649 137634 3526 21141 0 0 2d10h 6
LAV-Newskies#sh ip bgp neighbors 210.5.248.249 advertised-routes BGP table version is 21147, local router ID is 192.168.100.2 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 *> 202.4.32.0/21 0.0.0.0 0 32768 i *> 202.4.32.0/19 0.0.0.0 32768 i *> 202.4.48.0/22 202.4.32.242 100 32768 i
LAV-Newskies#sh ip route ospf 202.4.36.0/24 is variably subnetted, 2 subnets, 2 masks O E2 202.4.36.0/30 [110/1000] via 202.4.32.241, 2d09h, FastEthernet0/0 O 202.4.36.0/24 [110/2] via 202.4.32.241, 2d09h, FastEthernet0/0 202.4.32.0/24 is variably subnetted, 4 subnets, 3 masks O E2 202.4.32.144/28 [110/100] via 202.4.32.250, 01:31:00, FastEthernet0/0 O 202.4.32.8/30 [110/391] via 202.4.32.241, 2d09h, FastEthernet0/0 O 202.4.32.4/30 [110/51] via 202.4.32.241, 2d09h, FastEthernet0/0 O E2 202.4.34.0/24 [110/1000] via 202.4.32.241, 2d09h, FastEthernet0/0 192.168.100.0/32 is subnetted, 4 subnets O E2 192.168.100.8 [110/100] via 202.4.32.249, 2d09h, FastEthernet0/0 O E2 192.168.100.3 [110/100] via 202.4.32.250, 2d09h, FastEthernet0/0 O E2 202.4.52.0/23 [110/1000] via 202.4.32.241, 2d09h, FastEthernet0/0 O E2 202.4.48.0/22 [110/100] via 202.4.32.242, 2d09h, FastEthernet0/0 O E2 202.4.40.0/23 [110/100] via 202.4.32.241, 2d09h, FastEthernet0/0
Router Configuration from LAV-Newskies ======================================
router ospf 1 log-adjacency-changes network 202.4.32.253 0.0.0.0 area 0 default-information originate metric 1000 route-map DEFAULT_ONLY ! router bgp 17993 no synchronization bgp log-neighbor-changes network 202.4.32.0 mask 255.255.248.0 network 202.4.48.0 mask 255.255.252.0 aggregate-address 202.4.32.0 255.255.224.0 neighbor ebgp-newskies peer-group neighbor ebgp-newskies remote-as 23649 neighbor ebgp-newskies description Ebgp Peer with Newskies neighbor ebgp-newskies version 4 neighbor ebgp-newskies send-community neighbor ebgp-newskies remove-private-AS neighbor ebgp-newskies prefix-list announce out neighbor ebgp-newskies filter-list 20 in neighbor internal peer-group neighbor internal remote-as 17993 neighbor internal description ibgp peers neighbor internal update-source Loopback100 neighbor internal next-hop-self neighbor internal send-community neighbor internal prefix-list Sclout out neighbor 192.168.100.1 peer-group internal neighbor 210.5.248.249 peer-group ebgp-newskies neighbor 210.5.248.249 ebgp-multihop 255 neighbor 210.5.248.250 peer-group ebgp-newskies neighbor 210.5.248.250 ebgp-multihop 255 no auto-summary ! no ip http server ip classless ip route 0.0.0.0 0.0.0.0 63.100.218.29 ip route 63.100.220.253 255.255.255.255 63.100.218.29 ip route 63.100.220.254 255.255.255.255 63.100.218.29 ip route 172.16.1.0 255.255.255.0 63.100.216.89 ip route 192.168.100.1 255.255.255.255 202.4.32.252 ip route 202.4.32.0 255.255.248.0 Null0 200 ip route 202.4.48.0 255.255.252.0 Null0 200 ip flow-export destination 202.4.32.136 9876 ip flow-export destination 202.4.32.135 9876 ip as-path access-list 20 permit ^[0-9]*$ ip pim bidir-enable
ip prefix-list Sclout seq 5 permit 202.4.32.0/19 ! ip prefix-list announce seq 5 permit 202.4.32.0/19 le 32 logging 202.4.32.132 access-list 5 permit 0.0.0.0 access-list 6 permit 210.5.248.249
route-map DEFAULT_ONLY permit 10 match ip address 5 match ip next-hop 6
Hi Alex,
The problem is with the 202.4.48.0/22 address which is advertised over the router connected to Newskies. It is showing the the next hop as the router 202.4.32.242 but not as 0.0.0.0. I have announced the specific route but can anyone can help me if out why the bgp table is showing is below.
*> 202.4.48.0/22 202.4.32.242 100 32768 i
Yup, this looks confusing, but in fact it isn't a problem. In newer IOSes you will see this as a RIB failure in BGP, but your IOS is older so it doesn't have that feature.
The "problem" is that 202.4.48.0/22 is also know in another routing protocol:
O E2 202.4.48.0/22 [110/100] via 202.4.32.242, 2d09h, FastEthernet0/0 O E2 202.4.40.0/23 [110/100] via 202.4.32.241, 2d09h, FastEthernet0/0
OSPF distance is 110, iBGP distance is 200. So OSPF wins, hence giving you this "strange" result in the BGP table.
philip --
Hi Philip,
Thanks got bgp to annonce it properly. I though that OSPF does not inject its routes into BGP, you needed to have the redistribute command to do this?
Thanks for the assistance.
Regards
Alex
-----Original Message----- From: Philip Smith [mailto:pfs@cisco.com] Sent: Monday, 23 May 2005 12:27 a.m. To: Alex Abraham Cc: pacnog@pacnog.org Subject: Re: [pacnog] BGP Problem
Hi Alex,
The problem is with the 202.4.48.0/22 address which is advertised over the router connected to Newskies. It is showing the
the
next hop as the router 202.4.32.242 but not as 0.0.0.0. I have announced the specific route but can anyone can help me if out why the bgp table is showing is below.
*> 202.4.48.0/22 202.4.32.242 100 32768 i
Yup, this looks confusing, but in fact it isn't a problem. In newer IOSes you will see this as a RIB failure in BGP, but your IOS is older so it doesn't have that feature.
The "problem" is that 202.4.48.0/22 is also know in another routing protocol:
O E2 202.4.48.0/22 [110/100] via 202.4.32.242, 2d09h, FastEthernet0/0 O E2 202.4.40.0/23 [110/100] via 202.4.32.241, 2d09h, FastEthernet0/0
OSPF distance is 110, iBGP distance is 200. So OSPF wins, hence giving you this "strange" result in the BGP table.
philip --
Hi Alex,
Alex Abraham said the following on 24/05/2005 16:01:
Thanks got bgp to annonce it properly. I though that OSPF does not inject its routes into BGP, you needed to have the redistribute command to do this?
No, it's not a redistribution... Your /22 has been injected into OSPF (probably through a redistribute static - I don't have the config any more). And you have injected it into iBGP as well.
When the router comes to populate the *routing* table it will take the prefix with the shortest protocol distance - and OSPF beats iBGP.
What is in the BGP table is what gets announced to other BGP peers. So a "sh ip bgp" should indicate that your /22 is there also.
philip --
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