11-30-2010 03:41 PM - edited 03-04-2019 10:37 AM
We have 2 routers (3925) connect to the ISP through individual DS3 (T3) Connection. I want to ensure redundancy and proper load balancing. Sample configs and recommendations would be appreciated.
11-30-2010 04:28 PM
Considering the size of your infrastructure and speed acces, the best solution would be BGP.
In alternative, a load-balancing appliance between firewall and routers.
In either case, I recommend you hire a reputable consultant or certified cisco partner for the job.
11-30-2010 07:50 PM
Hello,
Please find below inputs
> Run HSRP between swich and two routers
> Run BGP between Router and ISP. I am just briefing BGP part below
> Let's assume you have one pool of /23. Divide it into two /24 parts
> Prepare three prefix list
ip prefix-list ISP-A-PRIMARY permit
ip prefix-list ISP-B-PRIMARY permit
ip prefix-list BACKUP permit
> Prepare two route-map for out direction
route-map ISP-A-PRIMARY permit 10
match ip address prefix-list ISP-A-PRIMARY
route-map ISP-A-PRIMARY permit 20
match ip address prefix-list BACKUP
set as-path prepend
route-map ISP-B-PRIMARY permit 10
match ip address prefix-list ISP-B-PRIMARY
route-map ISP-B-PRIMARY permit 20
match ip address prefix-list BACKUP
set as-path prepend
> Put this route-map in out direction with bgp peer respectively
neighbor x.x.x.x route-map ISP-A-PRIMARY out
neighbor y.y.y.y route-map ISP-B-PRIMARY out
Above will ensure load sharing between two ISP for incoming traffic. For out direction you can play with local-preference . It is much depends upon what
you are learning from provider end (default-route, Full BGP, Partial table)
Hope this helps
Regards
Mahesh
02-25-2011 04:12 AM
I am working in an ISP, facing a similar issue for a customer...
but the problem is the pool he's advertising is /24 one...if we divide further it will go to /25 & that is not acceptable in ISP's any suggestions???
04-08-2011 12:39 AM
Can any one update when the customer has /24 IP block.
04-08-2011 01:17 AM
Hi,
If customer is having /24 pool ISP will not accept in bracket of /25.
Now say If ISP agree on this then there is a way.
There are two approaches
1/ Accept /25 from customer and also ask customer to advt. /24 along with this. Advt. only /24 to upstream (from ISP) and hide /25 one. (no need to do
anything upstream will deny that).
So if someone on internet send traffic for first /25 it will follow /24 route and once that packet is entered the ISP network it will have two /25
route so once will be prefered.
Internet User------/24--------Upstream-------/24---------ISP-------First/25------CustomerA
|
|
Second /25
|
CustomerA.
2/ Next approach is customer advt. only two /25 and ISP itself advt. /24 by putting /24 route pointing toward null0 in one of his router.
Regards
Mahesh
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