Fault Tolerance

Unanswered Question
Dec 18th, 2007

Hi!

I've got 1841 series router with IPbase IOS . I've two Internet leased lines coming from two different ISP. First ISP giving me Ethernet termination which is going to my routers fe0/0. second ISP is giving v.35 termination which is going to my serial interface in router.

Now i want to have load balancing and fault tolerance, is it possible me to do.

Also let me know if i need to add any more information to above.

thanks in advance...

I have this problem too.
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nordick26 Tue, 12/18/2007 - 22:50

Hi,

do you run BGP with your ISP?

If yes, you can configure route-map to achieve load balancin for both incoming and outgoing traffic.

It should looks like this:

route-map LB_ISPA permit 10

match ip address [acl1 for one part of your network]

set metric 200

!

route-map LB_ISPB permit 10

match ip address [acl2 for second part of your network]

set metric 200

!

route-map LP_ISPA permit 10

match ip address [some IPSA routes if possible]

set local-preference 90

!

route-map LP_ISPB permit 10

match ip address [some ISPB routes if possible]

set local-preference 90

!

#under BGP process#

neighbor ISPA route-map LB_ISPA out

neighbor ISPA route-map LP_ISPA in

neighbor ISPB route-map LB_ISPB out

neighbor ISPB route-map LB_ISPB in

Like this, traffic from ACL1 will go throught ISPB and traffic from ACL2 will go throught ISPA.

If you are not running BGP with you ISPs, how do you route now? Default routes? or any other dynamic routing protocol?

HTH

Regards

Ivan

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Deepak Mahajan Thu, 12/20/2007 - 20:10

Hi Ivan!

No i'm not using any of the routing protocol including BGP. using default routes as of now. So unable to use second Link, finding any solution on this...

Richard Burts Fri, 12/21/2007 - 05:00

Deepak

If you are not using any dynamic routing protocol and are using only static routes then you can achieve load sharing over both links by using 2 equal cost static default routes. Configure one static default route with the serial interface next hop address and configure the other static default route with the FE interface next hop.

The static default route over the serial link will be withdrawn from the routing table is there is a failure on the serial link. However the static default route over the FE interface may still remain in the routing table even though the next hop address may no longer be available. To address this issue Cisco has introduced the feature of Reliable Static Routing using Object Tracking. This link will give information about this feature:

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a00804457cd.html

HTH

Rick

Deepak Mahajan Sat, 12/22/2007 - 01:47

Hi Rick!

Thanks for your reply...i'll just go thru and try to implement whatever said in link...

for your information following is my network setup...

LAN---->FW1--->RTR1--->(fe0/0)ISP1

LAN---->FW1--->RTR1---->(S0/0)ISP2

(Lan is connected to Firewall, firewall is connected to rtr, and on same rtr ISP1 is terminating on Fe0/0 and ISP2 is terminating on s0/0)

so do you think is it possible for me to use fail over using Reliable Static Routing using Object Tracking, and how can i get load balancing?

thanks in advance.

Richard Burts Sat, 12/22/2007 - 14:53

Deepak

There is an aspect of your environment that we need to clarify. I assume that to go to 2 different ISPs that your internal IP addresses must be translated into public addresses for each ISP. Is the address translation to be done on the firewall or on the router?

If there is a single LAN connected to a single firewall which is connected to a single router with 2 outbound connections, and if the address translation is to be done on the router then I believe that load balancing and failover can be accomplished using Reliable Static Routing using Object Tracking. If the address translation is to be done in the firewall then I do not see how the failover will work.

HTH

Rick

Deepak Mahajan Sun, 12/23/2007 - 23:29

Hi Rick,

Its 2nd aspect....single lan is connected to single firewall which is doing nating..which then connects to single router which have two outbound (two Internet leased lines) connections.

So now here is the problem can i do something with this, so that i can get fault tolerance...

thanks for your reply...

Deepak Mahajan Wed, 12/26/2007 - 00:47

Hi Sushil!

Thanks for your reply... so after all I've to purchase another router :( [which I've already guessed]

Please let me know if theres any solution arises...

Deepak Mahajan Thu, 12/27/2007 - 04:42

hi sushil!

do i need to get one more router?

as my current 1841 modular router is having one interface slot empty where i can fit any WIC(Fast Ethernet or serial).

will it help me?

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