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New Member

1841 router with second default route?

Hello,

I am new to routers, and am hoping someone can help me configure this simple setting.

Basically we have two 1841 routers, each with an internet connection (different ISPs). One is primary (all internal clients point their Default Gateway to this routers LAN interface IP), and the second router is in-case the primary router loses internet connectivity.

I want the primary router to auto fail over all requests it receives from inside clients, to the secondary router's LAN Interface IP, when it detects its internet interface is DOWN, or not functioning.

Is all I need to do is specify a second 0.0.0.0 0.0.0.0 route that points to the IP of the second router, or will I need to configure something else? Or is what I am trying to do even possible?

Thanks a lot for any help or suggestions on how better to accomplish my goal.

6 REPLIES

Re: 1841 router with second default route?

HSRP will fulfil your requirements. You need a config like the one below - susbstitute IP and other values as per your setup. Configure the standby IP of the HSRP as the default gateway for all your clients.

The primary router will track the ISP_interface and decrement the priority when the interface goes down and the backup router will start routing traffic at that point. Once the ISP_interface comes back up on the primary router it would preempt and start routing for the LAN clients.

Primary:

int f0/0

ip address 172.16.1.1 255.255.255.0

standby 1 ip 172.16.1.254

standby 1 priority 105

standby 1 track (int_to_isp)

standby 1 preempt

ip route 0.0.0.0 0.0.0.0 (ip_of_isp_next_hop)

Secondary:

int f0/0

ip address 172.16.1.2 255.255.255.0

standby 1 ip 172.16.1.254

standby 1 preempt

ip route 0.0.0.0 0.0.0.0 (ip_of_isp_next_hop)

HTH

Sundar

New Member

Re: 1841 router with second default route?

Thanks for the info. I will give that a try.

Re: 1841 router with second default route?

Good Luck and let us know how you did!!

New Member

Re: 1841 router with second default route?

Hey, one last question.

what will happen if the primary router itself dies? Will the secondary router still function as the backup? Or does HSRP require that the primary router actually be up and running IOS wise?

Thanks again.

Re: 1841 router with second default route?

When primary goes down the backup router will become the active router. On non-receipt of 3 (i believe) hellos from the active router, the backup router would consider the active router to be down and will become the active router.

HTH

Sundar

Re: 1841 router with second default route?

Hi,

If you are paying for both internet connections then you might want to consider GLBP as an alternative to HSRP - this would allow you to load balance between the two ISP's.

GLBP is described here:

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a008042fb97.html

HTH

Andrew.

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