12-16-2020 11:01 AM
I have 1 router with 3 ethernets.
2 of interfaces are ISP connections and I would prefer to 1 over the other. I added the weight command to neighbor statement. It took a while but it did start to prefer that. I want to make sure this is all I need to do to prefer this ISP over the other. I don't want it to flip unless we have an isssue with the preferred ISP circuit.
The 3rd interface is local subnets that are populated into BGP.
12-16-2020 11:20 AM
Hello,
weight is actually your best choice, since it is the first attribute for best path selection on a Cisco router. There is no way it can 'flip', so you should be fine.
12-16-2020 12:40 PM
Hello
@Georg Pauwen wrote:
Hello,
There is no way it can 'flip', so you should be fine.
Disagree, you can manaully shutdown a neigbour bgp peering to accomplish such a task
router bgp xx
neighbour x.x.x.x shutdown
12-16-2020 12:52 PM
I agree, there are even more ways to 'flip' this:
1. Pour a bucket of water over the router
2. Set the router on fire
3. Smash the router with a sledgehammer
Just kidding. I meant under normal operation of course, without manual intervention. I thought that was obvious...:)
12-16-2020 11:26 AM - edited 12-16-2020 12:37 PM
Hello
If you have a single wan rtr with dual isp ebgp peering then bgp weight attribute is applicable for egress traffic from your lan, and the reason why you say it took a while for that the weight to be appllied to your received routes is because after you applied the weight attribute you should have performed a soft reset on the bgp peers which would have applied the changes straight away to the bgp rib
(clear ip bgp soft * in/out)
The other thing you need to consider is ingress traffic from your ISP, I assume you would like the return traffic come via the same ISP your egress and to do that you could use as-path prepending on the least preferred ISP
route-map prepend
set as-path prepend <local ASN local ASN local ASN>
router bgp xx
neigbourt <isp2> route-map prepend out
12-16-2020 12:27 PM
100% right
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