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Shipping SMTP packets to a specific Gateway

Is it possible to configure a 3550 switch to make what are essentialy policy routing decisions based upon a port?? I have a 3550 switch in my customers DMZ which is the egress point off of the production network to the Internet. I have 2 ISP connected to the switch; both having great bandwidth.

The tranlation that I have for our MX and RDNS records is out of one of the ISP's only.

I would like to be able to configure the switch if at all possible so that when it received any SMTP packet outbound from our Mail Server, that it will make the decision to send it out the correct ISP.

I would like to the switch to load balance between the two gateways for all other traffic.

Please help. I looke at policy routing, but could not see where I would configure port criteria...


Re: Shipping SMTP packets to a specific Gateway


You can match smtp traffic with ACL. For all other traffic that you want to load balance configure 2 default routes and point it to the two ISPs. On 3550 switches you need to configure 'sdm prefer extended-match' command for PBR to work. You need a config like this one.

route-map test permit 10

match ip address 100

set ip next-hop

access-list 100 permit tcp any any eq smtp

int f0

description 'connects to LAN'

ip policy route-map test

ip route

ip route

sdm prefer extended-match



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