BGP configuration

[monsun1423]

hi,

we have router with two ISP each 45 mbps link(fast ether) terminating to it. what I want a full network redudancy(in case one down) and best route conveges and load balancing using both links.

pls suggest a configuration

isp A: 192.168.3.1

Isp B:172.16.14.2

lan

192.168.0.2

[Kishore Chennupati]

Hi Monsun,

Since you have one router(I am assuming its Cisco) multihomed to 2 ISP's you can use WEIGHT,  asp-path prepend  attibutes to achieve this so that you get a primary/backup kinda of failover redundancy.

Please see the config below

===ISP A  (Primary)

router bgp 300

neighbor 192.168.3.1 remote-as 100

neighbor 192.168.3.1 weight 40000

===ISP B  (backup)

router bgp 300

neighbor 172.16.14.2 remote-as 200

neighbor 172.16.14.2 route-map AS_PATH_PREPEND out

route-map AS_PATH_PREPEND

match ip address 101

set as-path 300 300 3000

access-list 101 permit ip 192.168.0.2 255.255.255.0 any

HTH,

Please rate if useful

[Latchum Naidu]

Hi,

See the below link will help you with two different ISP's with multihomed setup.
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a008009456d.shtml

Please rate the helpfull posts.

Regards,
Naidu.

[monsun1423]

kishor,

I want to use both ISP link as load-balancing , also in case one down other link can take up without any delay. I want to do tgat on single router itself.

also best path must be choosen from both with minimun latency

[Kishore Chennupati]

Hi Monsun.,

This is what I think you can do

You can use the maximum-paths 2 under bgp process on your router

since you are connected to 2 different ISP's.

BGP maximum-paths 2 works if the following criteria for selecting the BGP best path match:

weight, local preference, AS path length, origin code, MED.

if all these parameters are a match BGP can use two paths

However, there is a workaround .

bgp bestpath as-path multipath-relax    This commands helps you to load balance between 2 diff AS's outbound.

If you want inbound load balancing as well then , split your local LAN into two subnets and advertise with each one with different AS_PATH prepending

to the ISP's

HTH,

Regards

Pleas rate if helpful