08-15-2007 06:53 PM - edited 03-03-2019 06:20 PM
Hi,
I would like to check in-depth how does this BGP with maximum path 2 works. Does it load balance 50 50 between the 2 links that are of the same bandwidth?
The configuration is just by adding maximum path 2 at both the CE and PE end?
08-15-2007 07:08 PM
BGP maximum path 2 allows installation of a second path to a particular destination in the routing table if certain characteristics of the second path match that of the best path. As far the ratio of load balancing is concerned it's based on the switching type, cef/fast/process, configured on the ingress interface. BGP doesn't factor in the link size for choosing the path or load balancing. If process switching is enabled on the ingress interface then the ratio might be probably close to 50:50.
Have a look at this document.
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml#bgpmpath
HTH
Sundar
08-15-2007 07:24 PM
Best way i can suggest you to configure this by Lookpback interface configuration.
If you have Point to Point 2 Links terminated on both end single router.
interface loopback 0
ip address 1.1.1.1 255.255.255.0
router bgp 11
neighbor 2.2.2.2 remote-as 10
neighbor 2.2.2.2 update-source loopback 0
neighbor 2.2.2.2 ebgp-multihop
{Same configuraation at other end.}
Buth if you have two different ISP or two different router you should select another way for load balancing.
Maximum possible way for Load balancing available on below URL:
http://www.cisco.com/warp/public/459/40.html#conf1
Choose appropriate as your scenario.
Regards,
Dharmesh Purohit
08-15-2007 08:32 PM
Hi,
Thanks for the assistance. The BGP is running fine, just that the load balancing wasn't what I had expected. Seem like traffic is going out via 1 link and coming back via the other link.
Below is the config
PE
router bgp 234
redistribute connected
redistribute static
neighbor 192.19.50.1 remote-as 123
neighbor 192.19.50.1 activate
neighbor 192.19.50.1 soft-reconfiguration inbound
neighbor 192.19.50.6 remote-as 123
neighbor 198.19.50.6 activate
neighbor 198.19.50.6 soft-reconfiguration inbound
maximum-paths 2
no auto-summary
no synchronization
network 0.0.0.0
CE
router bgp 123
bgp log-neighbor-changes
neighbor 192.19.50.1 remote-as 234
neighbor 198.19.50.5 remote-as 234
maximum-paths 2
redistribute connected
redistribute static
neighbor 192.19.50.1 activate
neighbor 192.19.50.5 activate
no auto-summary
no synchronization
network 192.168.0.0
08-15-2007 09:21 PM
HI,
Refer link below for Load Sharing with BGP in Single Homed & Multi-Homed Environments:
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml
DO RATE ALL HELPFUL POSTS
Best Regards,
Guru Prasad R
08-16-2007 01:28 AM
It is also possible to load-balance across unequal cost paths for outside traffic using "bgp dmzlink-bw" command and communities (automatic).
Please refer to this document:
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