10-08-2024 09:35 AM
Hello Everyone,
We are having 2 neighbors on BGP with different ASNs on each neighbor. Is it possible to load balance the traffic on 2 neighbors? If yes what configuration will help to do the same. And also not seeing any traffic on second neighbor due to the Age factor of the neighbor(recently changed ASN on one of the neighbor) Following is the current BGP config. TIA
router bgp 46732
bgp log-neighbor-changes
neighbor 66.xx.xx.193 remote-as 22xxx
neighbor 66.xx.xx.193 description Provider A
neighbor 66.xx.xx.197 remote-as 12xxx
neighbor 66.xx.xx.197 description Provider B
!
address-family ipv4
network 67.xx.xx.xx mask 255.255.255.0
network 198.245.240.176 mask 255.255.255.240
neighbor 66.xx.xx.193 activate
neighbor 66.xx.xx.193 soft-reconfiguration inbound
neighbor 66.xx.xx.193 route-map FROM_22xxx in
neighbor 66.xx.xx.193 route-map TO_22xxx out
neighbor 66.xx.xx.197 activate
neighbor 66.xx.xx.197 soft-reconfiguration inbound
neighbor 66.xx.xx.197 route-map FROM_12xxx in
neighbor 66.xx.xx.197 route-map TO_12xxx out
maximum-paths 2
exit-address-family
Solved! Go to Solution.
10-08-2024 11:01 AM - edited 10-08-2024 11:03 AM
Hi @Mr.Kumar ,
If you want to load balance between the default routes received from the two service providers, you need to add the following commands to you bgp configuration:
router bgp 46732
bgp bestpath as-path multipath-relax <+++++ needed to ignore the fact that the paths come different ASNs
maximum-path 2 <++++++ needed to install both default routes in the RIB
Regards,
10-08-2024 09:55 AM
Hello,
One way to achieve your desired outcome it to configure the WEIGHT command. Assuming you're getting each route from both neighbors:
-Create a route map identifying half of the routes received from the neighbors (using a prefix list), then create a second route map identifying the other half of the routes.
-Make sure to include a separate permit statement in each route map to permit all other routes but no weight applied.
-Apply a weight to these routes (let's say 3000).
Apply one route-map IN to one neighbor and the other route-map on to the other neighbor.
Keep in mind this will load balance outbound traffic to those networks. It does not affect how your neighbors reach your netowrks.
Example:
ip prefix-list ONE halfOFroutes/prefix
ip prefix-list TWO halfOFroutes/prefix
route-map ONE permit 10
match ip address prefix-list ONE
weight 3000
route-map TWO permit 10
match ip address prefix-list TWO
weight 3000
route-map TWO permit 20
neighbor 66.xx.xx.197 route-map ONE in
neighbor 66.xx.xx.197 route-map TWO in
-David
10-08-2024 10:28 AM - edited 10-08-2024 10:29 AM
Hello David,
Firstly Thank you for your quick response. We are only getting one route on both the neighbors. Below is the prefix list and route map config.
Internet switch#sh run | sec route-map
neighbor 66.xx.xx.193 route-map FROM_22xxx in
neighbor 66.xx.xx.193 route-map TO_22xxx out
neighbor 66.xx.xx.197 route-map FROM_12xxx in
neighbor 66.xx.xx.197 route-map TO_12xxx out
route-map TO_12xxx permit 10
match ip address prefix-list TO_12xxx
route-map TO_22xxx permit 10
match ip address prefix-list TO_22xxx
route-map FROM_22xxx permit 10
match ip address prefix-list FROM_22xxx
route-map FROM_12xxx permit 10
match ip address prefix-list FROM_12xxx
Internet switch#sh run | i prefix-list
ip prefix-list FROM_12xxx seq 15 permit 0.0.0.0/0
ip prefix-list FROM_22xxx seq 15 permit 0.0.0.0/0
ip prefix-list FROM_3356 seq 5 permit 0.0.0.0/0
ip prefix-list TO_12xxx seq 30 permit xx.xx.105.0/24
ip prefix-list TO_22xxx seq 30 permit xx.xx.105.0/24
match ip address prefix-list TO_12xxx
match ip address prefix-list TO_22xxx
match ip address prefix-list FROM_22xxx
match ip address prefix-list FROM_12xxx
What are the possibilities in this case? TIA
10-08-2024 10:58 AM
10-08-2024 11:01 AM - edited 10-08-2024 11:03 AM
Hi @Mr.Kumar ,
If you want to load balance between the default routes received from the two service providers, you need to add the following commands to you bgp configuration:
router bgp 46732
bgp bestpath as-path multipath-relax <+++++ needed to ignore the fact that the paths come different ASNs
maximum-path 2 <++++++ needed to install both default routes in the RIB
Regards,
10-08-2024 11:21 AM
Hi Harold,
Thank you for the response, these command will restarts the BGP sessions right? Is there any other way that avoids the restart of current BGP sessions? TIA
10-08-2024 11:24 AM
first check if the both AS path have same count of AS
do
show ip bgp 0.0.0.0
check the AS
MHM
10-08-2024 11:29 AM
Hi MHM,
Here is the output
Internet switch#show ip bgp 0.0.0.0
BGP routing table entry for 0.0.0.0/0, version 34
Paths: (2 available, best #2, table default)
Multipath: eBGP
Not advertised to any peer
Refresh Epoch 1
12xxx, (received & used)
66.xx.xx.197 from 66.xx.xx.197 (148.51.255.173)
Origin incomplete, localpref 100, valid, external
rx pathid: 0, tx pathid: 0
Refresh Epoch 1
22xxx, (received & used)
66.xx.xx.193 from 66.xx.xx.193 (148.51.255.172)
Origin incomplete, localpref 100, valid, external, best
rx pathid: 0, tx pathid: 0x0
10-08-2024 11:50 AM
Multipath: eBGP <<- you already have this
Not advertised to any peer
Refresh Epoch 1
12xxx, (received & used) <<- one AS count
66.xx.xx.197 from 66.xx.xx.197 (148.51.255.173)
Origin incomplete, localpref 100, valid, external <<- this must be show multipath
rx pathid: 0, tx pathid: 0
Refresh Epoch 1
22xxx, (received & used) <<- one AS count
66.xx.xx.193 from 66.xx.xx.193 (148.51.255.172)
Origin incomplete, localpref 100, valid, external, best
rx pathid: 0, tx pathid: 0x0
I need to check why the router refuse to add second path as multipath
MHM
10-09-2024 01:00 AM
Multipath: eBGP <<- you already have this
Not advertised to any peer
Refresh Epoch 1
12xxx, (received & used) <<- one AS count & different AS
66.xx.xx.197 from 66.xx.xx.197 (148.51.255.173)
Origin incomplete, localpref 100, valid, external <<- this must be show multipath
rx pathid: 0, tx pathid: 0
Refresh Epoch 1
22xxx, (received & used) <<- one AS count & different AS
66.xx.xx.193 from 66.xx.xx.193 (148.51.255.172)
Origin incomplete, localpref 100, valid, external, best
rx pathid: 0, tx pathid: 0x0
what you need additional as @Harold Ritter mention
router bgp xxx
address family ipv4 unicast
bgp bestpath as-path multipath-relax <<-
GoodLuck
MHM
10-08-2024 11:28 AM
Hi @Mr.Kumar ,
I do not think these commands will reset the session, but it is safer to implement these changes inside a maintenance window.
BTW, it is always a good idea to do a "clear bgp ipv4 uni * soft in" after you modify the inbound policy.
Regards,
10-15-2024 09:27 AM
Thanks to each and everyone, i have tested this last night and it worked perfectly.
10-15-2024 09:35 AM
You are so welcome
MHM
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