dual router with dual ISP load balancing

Unanswered Question
Apr 13th, 2009

Dear Pros,

I need your help in designing the dual isp scenarios. There are 2 cisco routers installed as edge internet routers. Each router's WAN connected to defferent ISP.The gigabit 0/0 of both routers are connected in the common 172.20.21.0 network segment with hsrp VIP 172.20.21.1. The physical interface IP of those routers is 172.20.21.5, 172.20.21.6. The failover firewall outside interface connected to this same segment with IP of 172.20.21.3 and 172.20.21.4. The firewall default gateway is HSRP VIP of router 172.20.21.1.


Please help me how can we achieve the dual ISP load balancing using those 2 separate rouetrs. If one router fails another should take over as redundant router.

Thanks in advance

swami

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Giuseppe Larosa Mon, 04/13/2009 - 11:38

Hello Arumugasamy,


see the following examples for BGP multihoming (if you are interested in BGP).


If you haven't got your own public ip address block you need to use NAT and this leads to be able to achieve redundancy but not load balancing.


See also:


http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml#conf5


and for NAT multihoming design


http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a0080091c8a.shtml



Hope to help

Giuseppe


arumugasamy Fri, 04/17/2009 - 23:01

Dear,


The customer does not like to go for BGP solution.


Is there any way to do this?


Thanks

swami



Giuseppe Larosa Sat, 04/18/2009 - 01:40

Hello Swami,

without BGP you can still offer at least redundancy.

You can consider to use reliable static routing on the two edge routers.

In this way you use an ip sla or rtr object to check the healthy of each WAN link /ISP network with an IP reachability test.


see


http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html


Then you should redistribute these static routes in an IGP protocol (EIGRP or OSPF) with better seed metric on the primary router.

Using HSRP or GLBP on the client Vlans complete your solution.


Hope to help

Giuseppe


arumugasamy Fri, 04/17/2009 - 23:05

Dear,


My customer requirement is dual edge routers scenarios.

There are no way except BGP

SWAMI

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