07-30-2011 07:20 AM - edited 03-04-2019 01:08 PM
Dear,
I am an ISP that have multi homing with two upsteam provider. I have BGP configuration with both ISP.
ISP - A : send me full routing BGP table and it worked with me fine when the ISP-B disconnected ( for outgoing and incoming traffic)
ISP-B : send me the defualt route 0.0.0.0 only,
when both are connected the outgoing always from ISP-A and incoming from ISP-B. however, whenever i disconnect ISP-A I cannot receive or send any traffic through ISP-B .
apprciate your help and cooperation.
regards
MHS
07-30-2011 07:27 AM
Since you are multi homing, you need to received full route from both ISP. Ask your ISP B to provide you full route and remove the default route from the advertisement.
Execute ip route google_ip_address and see if its point to your ISP interface IP. If it is;
- you may be receiving full route from ISPB but you may not be advertising your prefix to ISPB correctly
- your ISPB may have ACL in its interface that block your outgoing or incoming
In the first place, why thus ISPB only advertise default route to you? There might be some misunderstanding.
07-30-2011 07:31 AM
Thanks Danilo,
my ISP-B have only the defualt route from their upstream provider. how we can send the full route if he doesnt have it?
There is no other way to do it?
regards
MHS
07-30-2011 07:34 AM
I just edited my reply
Since ISPB can only advertise default route to you from his upstream ISP, check with ISPB whether his upstream ISP know that you are connected to him and you need internet transit. The ISP above ISPB might not know you are connected to ISPB and they may not have open your access to their ACL to ISPB.
07-30-2011 07:39 AM
Yes the upstream provider of ISP-B knows and they allow my prifex through their network.
I tested through looking glasss and I can see that the traffic is coming through ISP-B, but why I cannot receive anything from ISP-B ( no incoming and no outgoing ) when ISP-A become down.
Thanks
MHS
07-30-2011 07:44 AM
This means your BGP advertisement is correct as you can see it in looking-glass thru ISPB (and its upstream). The problem here could be ACL from ISPB and/or ISPB upstream. Check with your ISPB at their network and ask them to check with their upstream ISP as well. Check your ACL also to be sure
Btw, thus the router connected to ISPA and ISPB are the same router or different routers? When you test the connection thru ISPB did you use the router that connected to ISPB (i.e. ping google from router connected to ISPB)?
07-30-2011 07:54 AM
I am working closely with ISP-B and there is no ACL blocking the outgoing traffic.
How we can confirm that I dont have problem in my configuration.
MY show ip bgp out put is
Network Next Hop Metric LocPrf Weight Path
*> 0.0.0.0 ISP-B interface 0 ISP-B i
after this route there is BGP routes from ISP-A
Show ip route is
B* 0.0.0.0/0 [20/0] via ISP-B interfecae , 00:46:24
after that the BGP route to ISP-A
1.0.0.0/8 is variably subnetted, 839 subnets, 14 masks
How I can force my traffic to go through ISP-B, I used to shut ISP-A to do it but still as I inform you it didnt work once I shut down ISP-A
I am using one router for both ISPs
thanks
07-30-2011 08:11 AM
can you execute "show ip route google_ip_address" if it points to ISP-B interface?
07-30-2011 08:24 AM
Router#show ip route 209.85.227.105
Routing entry for 209.85.226.0/23, supernet
Known via "MY_AS", distance 20, metric 0
Tag AS_ISP-A, type external
Last update from IP-interface of ISP-A 02:03:01 ago
Routing Descriptor Blocks:
*IP-interface of ISP-A, from IP-interface of ISP-A, 02:03:01 ago
Route metric is 0, traffic share count is 1
AS Hops 3
Route tag 39273
MPLS label: none
See from the above output only to ISP-A
kindly advice
regards
MHS
07-30-2011 08:27 AM
I thought you shutdown your connection to ISPA?
07-30-2011 08:31 AM
You want me to shut down ISP-A and send the result?
07-30-2011 08:34 AM
sry, i thought you are doing testring now. you can only do that during non-production time. can you post your configuration? you can PM me if you have concern to post here.
07-30-2011 08:37 AM
I can shut down the ISP-A no problem if you want.
I prefer to send you configuration through PM.
regards
07-30-2011 08:41 AM
send me the configuration first.
07-30-2011 08:51 AM
sent
Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: