03-21-2008 07:15 AM - edited 03-03-2019 09:13 PM
We have a public AS that we are advertising using two BGP peers. How can we change the weight or administrative distance on one to make it less preferable to incoming traffic?
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03-21-2008 07:51 AM
The sample will work for both (1 x Router or 2 x Router in iBGP)
03-21-2008 07:29 AM
Hi,
To enfluence incoming traffic, use PREPEND. You can also use MED but not all ISP honors MED.
If its not enough, try advertising your prefix in two in your preferred ISP and in one in your less-preferred ISP.
Regards,
Dandy
03-21-2008 07:35 AM
Hey Dandy!
I appreciate the response. I cant seem to find good documentation anywhere regarding prepend or its use. This is what I dont understand at this point.
Thanks
03-21-2008 07:45 AM
Hi,
Check this link http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080093f2c.shtml
The link is HSRP and BGP, just focus on the prepend :) in your situation (R2 for example) you can PREPEND more....
set as-path prepend 100 100 100 100 nnn
...I think the maximum is 8 prepend
BTW, what is your setup? 2 x Router (each peer to different ISP) or 1 Router that peers to both ISP.
Regards,
Dandy
03-21-2008 07:46 AM
Currently it is 1 router that peers to both ISPs. Within the next couple weeks- it will be 2 routers (then 3) peered to 3 different spots.
03-21-2008 07:51 AM
The sample will work for both (1 x Router or 2 x Router in iBGP)
03-21-2008 08:41 AM
Thanks! I am implementing changes tonite. I will update on here if it fixed the issue.
Thanks again!
03-24-2008 07:13 AM
This resolved the issue. Thanks!
03-26-2008 06:06 AM
for incoming traffic, you just have limited influence over the remote side's decision like AS prepend, or route origin (IGP/incomplete). MEDS will not work in multihomed scenario. If the remote side decides to use LP, it will override all your efforts.
The best way to control incoming traffic is to use different subnet mask to advertise the same route to different remote sides.
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