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Multiple last resort gateways for different types L4 of traffic??

kayasaman
Level 1
Level 1

Hi,

my company was considering implementing a service where multiple layer 4 traffic is routing through different ISP's.

We currently have 3 ISP's with aggrogate 60Mbps bandwidth approx. for our WAN networking system which is connected to the internet. 2 ISR 2921's will be used as the main gateway's to provide gateway of last resort connectivity to our clients.

Our current plan is to use BGP to talk between the ISP's in order to create redundant paths if something goes wrong with the main ISP service. Both routers will be used in an 'active/backup' setup and not to load balance traffic between them.

Is it possible using this topology and hardware to create different destinations for various L4 protocols??

So in this example having ISP: A, B, and C

with all IMAPv4 traffic routed to ISP A

HTTP/HTTPS traffic routed to ISP B

and SMTP traffic to ISP C

can this be done?

We have currently been looking at creating route-maps however within the documentation and IOS internal help commands havne't managed to see anything covering layer 4.....

Our current thoughts are to either create multiple policies covering the different protocols; load balance the WAN links and then create extended ACL's to block traffic from the unrequired links, (although this might result in service time-outs).

Can anyone suggest anything or point us into the correct direction???

Many thanks and best regards,

Kaya

2 Replies 2

Amit Singh
Cisco Employee
Cisco Employee

Kaya,

You can achieve the same by using PBR with L4 ACL's and setting multiple DG's. But this will be a very tedious configuration and less controllable with mor manual intervention and troubleshooting headaches.

You also mentioned that you are planning to use BGP with the providers? Have you got you own AS# and IP Block? Have you looked at the PFR (Performance routing)?

I think PFR a.k.a OER is the right option for you. You use multiple ISP's and route you application to a primary link with other link as the backup based on the metrics and path cost ( mechanisms used by PFR for routing). I recently designed a PFR solution for one of my customer with the same type of requirements. In the initial phase, they will using this for purely load-balancing across ths links and in a few months time, they will put their applications load-balancing policies.

Please see the links below on thorough understanding and design criterias for PFR :

http://docwiki.cisco.com/wiki/PfR:Home

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6554/ps6599/ps8787/prod_white_paper0900aecd806c5077.html

HTH, Please rate if it does.

-AS

Thank you!

I think this is more a long the lines of what we are looking for as ease of maintenance is paramount, and hence I think this works in conjunction with load balancing also (if not mistaken) meaning that if a link goes down the system can use the other 2 links without too much congestion occuring.

We do have our own IP block at this time and our own autonomous system number as we are quite a large firm in our country.

Regards,

Kaya

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