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Community Member

load balance accross 2 point to point t/1's

I have 2 offices connected using 1720 routers with 2 t/1's connected to each router. I would like to utilize both t/1's bandwidth. It seems as only 1 t/1 as used at a time. Config below:

Router A

e0

ip address 192.168.71.1 255.255.255.0

s0

ip address 192.168.5.2 255.255.255.252

s1

ip address 192.168.5.6 255.255.255.252

ip route 0.0.0.0 0.0.0.0 192.168.71.4

ip route 172.17.4.0 255.255.255.0 192.168.5.1

ip route 172.17.4.0 255.255.255.0 192.168.5.5

ip route 192.168.4.0 255.255.255.0 192.168.5.1

ip route 192.168.4.0 255.255.255.0 192.168.5.5

ip route 192.168.71.0 255.255.255.0 192.168.71.4

Router B

e0

ip address 192.168.4.1 255.255.255.0

s0

ip address 192.168.5.2 255.255.255.252

s1

ip address 192.168.5.6 255.255.255.252

ip route 0.0.0.0 0.0.0.0 192.168.4.2

ip route 172.17.4.0 255.255.255.0 192.168.4.2

ip route 192.168.71.0 255.255.255.0 192.168.5.2

ip route 192.168.71.0 255.255.255.0 192.168.5.6

7 REPLIES
Silver

Re: load balance accross 2 point to point t/1's

on the B router you are missing the static utilizing the other T1

missing

ip route 172.17.4.0 255.255.255.0 192.168.5.1

I

Bronze

Re: load balance accross 2 point to point t/1's

To many typos on the cleanup config to figure out what your doing. This has the same addresses on both ends of the t1s

Community Member

Re: load balance accross 2 point to point t/1's

Made a mistake when I pasted the config.

Router A

e0

ip address 192.168.71.1 255.255.255.0

s0

ip address 192.168.5.2 255.255.255.252

s1

ip address 192.168.5.6 255.255.255.252

ip route 0.0.0.0 0.0.0.0 192.168.71.4

ip route 172.17.4.0 255.255.255.0 192.168.5.1

ip route 172.17.4.0 255.255.255.0 192.168.5.5

ip route 192.168.4.0 255.255.255.0 192.168.5.1

ip route 192.168.4.0 255.255.255.0 192.168.5.5

ip route 192.168.71.0 255.255.255.0 192.168.71.4

Router B

e0

ip address 192.168.4.1 255.255.255.0

s0

ip address 192.168.5.1 255.255.255.252

s1

ip address 192.168.5.5 255.255.255.252

ip route 0.0.0.0 0.0.0.0 192.168.4.2

ip route 172.17.4.0 255.255.255.0 192.168.4.2

ip route 192.168.71.0 255.255.255.0 192.168.5.2

ip route 192.168.71.0 255.255.255.0 192.168.5.6

Community Member

Re: load balance accross 2 point to point t/1's

Router B does not need to send 172.17.4.0 out the t/1's that destination is on the ethernet side of the router.

Bronze

Re: load balance accross 2 point to point t/1's

I wonder why you still have 'ip route 192.168.71.0 255.255.255.0 192.168.71.4' configured on Router A when this route is a directly connected network. The same case with Router B. Afaik, for directly connected networks, you don't need to add it in the routing table.

The serial interfaces could be using the default 'per-destination' load-balancing. Check if the serial interface is configured for fast-switching ('ip route-cache' command). To utilize both links at the same time, use per-packet load-balancing by disabling fast-switching. For more information on per-destination and per-packet load-balancing, check out the following link:

http://www.cisco.com/en/US/tech/tk826/tk365/technologies_tech_note09186a0080094820.shtml

HTH.

Community Member

Re: load balance accross 2 point to point t/1's

thanks I will try turning off ('ip route-cache' ).

Silver

Re: load balance accross 2 point to point t/1's

Warning: Turning of fast switching (no ip route-cache) forces all packets to be process switched, which greatly increases CPU consumption and forwarding delays. Instead, you should use "Cisco Express Forwarding" and specify "per packet" load sharing. CEF consumes lots of RAM, but RAM can be added while CPU cycles are limited.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

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