Filtering BGP Route Advertisements to AWS Transit Gateway

[Mike Elliott]

I have a 4331 router that has BGP setup on it.  We use BGP to get route updates to our AWS infrastructure.  There are several Transit Gateways that we connect to and exchange BGP information.  The problem is that our BGP instance is advertising routes between Transit gateways.  I'd like to filter out the routing information that is exchanged so that it ONLY advertises the routes I want it to and not any other routes.

I tried using prefix-lists and the distribute command but it didn't work as expected.  If I understand it, ORF can be used to filter routes but both ends need to support it (I am relatively certain AWS does not support ORF).

Is there another way to accomplish this?

Thanks

[Jon Marshall]

Never used AWS but should just be BGP route filtering from your description. 

I usually use a route map with prefix lists and it works fine. 

Did you do a soft reset after applying your configuration ?

Jon

[Mike Elliott]

I did do a soft reset... 

I'll try it again

[paul driver]

Hello

ORF needs to be appended on either side the bgp peering, so from the rtr you want ORF to occur then you send the filter list  towards that router

Example
rtr1 ( your router)
ip prefix-list stan seq 5 deny 1.0.0.0/8
ip prefix-list stan seq 10 deny 2.0.0.0/8
ip prefix-list stan seq 99 permit 0.0.0.0/0 le 32

router bgp 1
neighbor 10.1.12.2 pref stan in
neighbor 10.1.12.2 capability orf prefix-list send

rtr2
router bgp 2

network 1.0.0.0
networt 2.0.0.0
neighbor 10.1.12.1 capability orf prefix-list receive

[Mike Elliott]

Thanks Paul, but I don't think ORF is going to work against a AWS transit gateway

[paul driver]

Yeah 

apologies didnt read your OP correctly in which you stated that  

How are you filtering at present- can you share ?

[Georg Pauwen]

Hello,

post what you have tried with prefix and distribute lists, as stated by Jon, that is the common way to filter routes, so maybe you missed something...