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Adding a Second T1 for load sharing and failover Questions

Hi Guys,

I have two Cisco 3825 routers at he edge of my network i.e. the public side connecting us to the Internet. Currrently one T1 is active and the other one at stand by using HSRP between the routers. we have made a request tomake the stand by T1 active and I have issues withthe configuration since wedo not run any IGP between the routers.

there is BGP configuration on the routers for failover and I am sure the next configuration will be using BGP too but having static routes, I don't know if I can assign metrics to the link and BGP configuration to have both T1s actrive and have load sharing between them. any thought tohelp me configure this scenarion is greatly appreciated.

Thx,

Masood

1 REPLY

Re: Adding a Second T1 for load sharing and failover Questions

More info on the topology would help us provide you the optimal solution.

You can configure two HSRP groups on the 3825s and add two default routes on the layer 3 device connected to the 3825s to load balance outbound traffic.

3825_1:

int f0/0

172.16.1.1 255.255.255.0

standby 1 ip 172.16.1.3

standby 1 priority 150

standby 2 ip 172.16.1.254

3825_2

ip add 172.16.1.2 255.255.255.0

standby 1 ip 172.16.1.3

standby 2 ip 172.16.1.254

standby 2 priority 150

On the router/layer 3 device connecting to the two 3825s, add two static routes as follows.

ip route 0.0.0.0 0.0.0.0 172.16.1.3

ip route 0.0.0.0 0.0.0.0 172.16.1.254

This would make the traffic leaving your network load balanced across both 3825s. To load balance inbound traffic from the Internet provide more info on your topology like;

a. are you connected to one or two ISPs?

b. how many public IP blocks do you have? If you are using more than one ISP then which provider does the IP belong to?

c. Are you learning default route via BGP or partial/full routing from the ISP?

d. what's connected to the two 3825s on your end?

e. is running IGP an option on your inside router or firewall?

HTH

Sundar

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