06-16-2008 05:45 AM - edited 03-03-2019 10:22 PM
As a lab, I am trying to run BGP between a 2811 (running advipsvcs 12.4(15)T1) and a 3560 in L3 switching mode (running ipsvcs 12.2(25)SEE3). The two devices become BGP peers, but never seem to exchange any routes! The configuration is simple -- two different AS with several network statements each (the router has loopback addresses, the switch 2 ports configuring as no swi and with IP addresses). Here are the configs:
Router:
router bgp 6002
no synchronization
bgp log-neighbor-changes
network 108.4.0.0
network 108.6.0.0
network 108.7.0.0
neighbor 108.4.0.1 remote-as 6502
no auto-summary
Switch:
router bgp 6502
no synchronization
bgp log-neighbor-changes
network 100.1.1.0
network 101.1.1.0
network 102.1.1.0
network 105.1.1.0
network 108.4.0.0
neighbor 108.4.0.2 remote-as 6002
no auto-summary
I can't see how it could be simpler than that, but neither device sees any bgp routes. show ip bgp shows the session established and keep-alives being processed...but no route refreshes at all.
Any ideas?
Thanks!
Solved! Go to Solution.
06-16-2008 06:14 AM
The show ip bgp should be populated in the router with the routes received from the neighbor and its local routes.
The local routes are important as they are needed for advertisement.
You need to make sure you are matching the networks in the routing table so they can be added into BGP.
Per your routing table output and your BGP configuration, they are not matching.
For instance, in the router - you have /24 subnets for the interfaces but the BGP network statement does not contain the subnet information (mask).
For example:
Router routing table:
108.0.0.0/16 is subnetted, 1 subnets
C 108.4.0.0 is directly connected, FastEthernet0/0
Your BGP network statement should be:
network 108.4.0.0 mask 255.255.0.0
HTH,
__
Edison.
06-16-2008 06:02 AM
Please post the routing table from both devices along with the bgp table.
show ip route
show ip bgp
Thanks
__
Edison.
06-16-2008 06:06 AM
Certainly -- sho ip bgp is empty, so I added sho ip bgp summary...
Router#sho ip rou
Codes:
Gateway of last resort is not set
102.0.0.0/24 is subnetted, 1 subnets
C 102.1.1.0 is directly connected, Loopback2
100.0.0.0/24 is subnetted, 1 subnets
C 100.1.1.0 is directly connected, Loopback0
101.0.0.0/24 is subnetted, 1 subnets
C 101.1.1.0 is directly connected, Loopback1
108.0.0.0/16 is subnetted, 1 subnets
C 108.4.0.0 is directly connected, FastEthernet0/0
105.0.0.0/24 is subnetted, 1 subnets
C 105.1.1.0 is directly connected, Loopback4
Router#sho ip bgp
Router#
Router#sho ip bgp summ
BGP router identifier 105.1.1.1, local AS number 65001
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
108.4.0.2 4 65002 22 22 1 0 0 00:10:40 0
Router#
pod2-layer3-switch#sho ip rou
Codes:
Gateway of last resort is not set
108.0.0.0/16 is subnetted, 3 subnets
C 108.4.0.0 is directly connected, FastEthernet0/1
C 108.6.0.0 is directly connected, FastEthernet0/2
C 108.7.0.0 is directly connected, FastEthernet0/3
pod2-layer3-switch#sho ip bgp
pod2-layer3-switch#
pod2-layer3-switch#sho ip bgp summ
BGP router identifier 108.7.0.1, local AS number 65002
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
108.4.0.1 4 65001 20 20 1 0 0 00:10:22 0
pod2-layer3-switch#
06-16-2008 06:14 AM
The show ip bgp should be populated in the router with the routes received from the neighbor and its local routes.
The local routes are important as they are needed for advertisement.
You need to make sure you are matching the networks in the routing table so they can be added into BGP.
Per your routing table output and your BGP configuration, they are not matching.
For instance, in the router - you have /24 subnets for the interfaces but the BGP network statement does not contain the subnet information (mask).
For example:
Router routing table:
108.0.0.0/16 is subnetted, 1 subnets
C 108.4.0.0 is directly connected, FastEthernet0/0
Your BGP network statement should be:
network 108.4.0.0 mask 255.255.0.0
HTH,
__
Edison.
06-16-2008 06:29 AM
Edison,
That worked. I thought the mask information was optional in BGP...I guess not. I will obviously have to read some more.
Thanks
Jim
06-20-2008 09:28 PM
BGP works differently when you have no auto-summary in the config. If you leave this out then bgp starts to be classful and any routes in a class that match will allow the class to be advertised not just the specific.
If you put no auto-summary in the config then bgp expects to see the exact route in the routing table before it will announce them.
06-21-2008 04:01 PM
If you are using the no auto-summary option make sure you have a route in place that point s to dest Ex
Sh ip route
x.x.x.x y.y.y.y z.z.z.z
x.x.x.x= src
y.y.y.y sn
z.z.z.z dest
Make sure that the route matches the route in the BGP table and if not you will not see the routes under BGP
Basically there are two tables
1. RIB Routing table
2. BGP Table
for a route to be adv via BGP under these circumstances must have an existing route in the routing table and must match the route in the routing table
Ex.
In RIB
ip route x.x.x.x 255.255.255.0 y.y.y.y
if this is in place BGP should adv your route
To verify
type in the following
show ip bgp x.x.x.x
show ip route
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