01-24-2008 03:24 PM - edited 03-03-2019 08:25 PM
Hello All,
I have two routers 2811's one with a DS3 and the other with an ethernet feed from two different providers. I am running BGP for the providers and IBGP between routers. I haver very well balanced inbound traffic but I have 90+% of my traffic goes out of one provider. Do you know a way to me to add hops to one of my providers to try to force more traffic to the other. or any other idea ??
Thanks
Casey
01-24-2008 04:52 PM
Casey,
You might want to take a look at these docs..
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml
http://www.cisco.com/en/US/products/ps6017/products_feature_guide09186a00804181b4.html
HTH,
Hieu
01-24-2008 06:09 PM
You might also want to look at OER/PfR which can dynamically load balance.
01-26-2008 01:06 PM
Hi Casey,
I know a way to add AS-numbers to the path attributes in updates from the ISPs to cause traffic to go through the other router.
You should configure a route map to do this and an access-list to select to which routes you add an additional AS-number.
route-map ADD-AS permit 10
match ip address 1
set as-path prepend 65000
route-map ADD-AS permit 20
You should configure this route-map on the overloaded router under the BGP process with the "neighbor x.x.x.x route-map ADD-AS in" command.
This route-map will do the following:
It will add an additional AS-number (e.g. 65000) to the path attribute of an update coming from the x.x.x.x neighbor for routes permitted by access-list 1.
It will do nothing to routes denied by the access-list.
The result may be that BGP will not choose these selected routes for forwarding packets according to the BGP path selection process, step 4.
It is necessary to note, that a more direct way to achieve this result is to configure the local preference for some selected routes. See the BGP path selection process, step 2.
Cheers:
Istvan
01-27-2008 12:52 AM
Hi,
Q1
Do you received full internet route from both provider or you received full internet route from provider-A (>90%) and only default route from provider-B (<10%)?
Q2
If you received full internet route from both providers, do you see from the "show ip bgp" that you have two paths to the same destination? This is to make sure that iBGP is configured and working properly.
Regards,
Dandy
01-28-2008 06:32 AM
Hey Dandy, The answer to both your questions is yes and yes... I have not tried too many things I am still tring to get a pattern to decide the best way to fix this...
Thanks for you reply
Casey
01-30-2008 03:22 AM
Hi,
I have the same situation and my problem is solved by using two HSRP sessions. Each router is used as primary for half of the traffic (I divvied my ip space to two part for example /22 will be 1/23 and 2/23). The traffic from 1/23 is sent to the first router via HSRP and the traffic from 2/23 is sent to the other router via HSRP. This solution also provides you with redundancy in case that one router goes down.
OER is another possible option, but you may end up as test lab for Cisco bugs.
Good luck
A.Amor
02-01-2008 09:04 AM
You are looking for a way to share your traffic outbound.
Recap:
2 Different Providers
Both sending full routes
BGP with both peers
iBGP between your routers
What I don't understand is the bandwidth on both links? are they equal?
Have you tried shutting one bgp session down and seeing doing a sh ip bgp
How does your internal traffic know where to go? Is there something set-up that it allways hits one router over the other? If 90% of your traffic hits one router then it will always assume that outbound because to go to the other router outbound will be one more hop.
04-28-2008 10:11 PM
Dear Casey ,
I think for outbound BGP balancing ( if you receiving default routes from both upstream ) you may have to use PBR .
Prefix A+ Prefix B
Prefix A -----Outgoing thru ISP A
Prefix B -----Outgoing thru ISP B
Route-map ISP_B permit 10
Match as-path 10
Set local preference 200
Router bgp XXXX
neighbor ISP_B route-map ISP_B in
This will set ISP_B routes has a Local preference of 200 and ISP_B will be the default outgoing .
Now make a route-map to make Prefix_A outgoing thru ISP_A , you can use object tracking for this route-map to make sure that prefix_A outgoing is going only when there is reachability thru ISP_A
Route-map outgoing permit 10
Match ip address prefix A
Set ip next-hop ISP_A
Route-map outgoing permit 10
Match ip address prefix A+B
----------this will follow default routing table which is ISP B
Regards,
Haris
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