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sohail161982
Beginner

need help on BGP load balancing between 4 links

Hello everyone

I need some help regarding BGP load balance and failover. Here is my scenario. I am currently connected with two upstream provider with four physical interface for failover/redundancy. Now I need to configure loadbalance with failover between those pair of interfaces. To make my scenario more clear please see the attached picture.

1 ACCEPTED SOLUTION

Accepted Solutions

"maximum-paths 2" will load-balance only your outbound traffic. the load-balancing will be towards only one ISP

In-bound load-balanccing can be acheived to some extend by

1.dividing your /21 subnet to two /22 and avertise it to both neighbors

2. for one neighbor add extra as-path using as-path prepedning for one subnet of /22

3. for the other neighbor, advertise the other /22 with as-path prepend

This will help only  if you have good amount of traffic to both subnets of /22

Thank you

Raju

View solution in original post

7 REPLIES 7
Raju Sekharan
Cisco Employee

Hi Monirul

1. you have 2 links to each ISP. Are you going to have peering using single IP address for these 2 links? Are you going to use any bundling on these interfaces?

2. Are you going to receive complete routing table from ISPs or default-routes?

3. Do you have your own public AS and do you need to advertise your rnage of Public addresses to outside?

Raju

Hi Raju

Please find the answer inline.

1. you have 2 links to each ISP. Are you going to have peering using  single IP address for these 2 links? Are you going to use any bundling  on these interfaces?

---Yes i am using peering IP for all the individual link. That means i have four peer ip.

---No I am not using any bundling on these interfaces right now.

2. Are you going to receive complete routing table from ISPs or default-routes?

---- I am receiving default route only.

3. Do you have your own public AS and do you need to advertise your rnage of Public addresses to outside?

---Yes i have my own AS along with /21 IP and I advertise them as per requirement.

Hi,

to load-balance outbound then simply configure maximum-paths 2 under BGP process

Regards.

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.

Hi Alain

Thanks for your reply. I need to load-balance my inbound traffic. Will "maximum-paths 2" accomplish the task ? I need failover and load-balance both. Currently I am doing manual inbound load-balance with prefix-list.

Hi,

no maximum-paths is only for outbound load balancing.

Regards.

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.

"maximum-paths 2" will load-balance only your outbound traffic. the load-balancing will be towards only one ISP

In-bound load-balanccing can be acheived to some extend by

1.dividing your /21 subnet to two /22 and avertise it to both neighbors

2. for one neighbor add extra as-path using as-path prepedning for one subnet of /22

3. for the other neighbor, advertise the other /22 with as-path prepend

This will help only  if you have good amount of traffic to both subnets of /22

Thank you

Raju

View solution in original post

Thanks Raju its working. Initialy it was not working because of the prepending to same SP restriction on my upstram.

Thanks for your help.

Thanks

Sohail