The Email Security — Server appliance is equipped with an ether1 management interface and a pether3 network monitoring interface.
Note
If IP routing is not configured, inbound and outbound SMTP traffic can use both the ether1 and pether3 interfaces.
The following example illustrates how to configure IP routing where ether1 and pether3 interfaces are on different subnets. Because ether1 and pether3 are on different subnets, no SMTP traffic is allowed on ether1. As a result, remote MTAs cannot be on the same subnet as ether1.
In this example, the default gateway (172.16.1.1) will be on ether1, but a different gateway will be on pether3 for SMTP traffic. As shown below, a static IP route is configured for the next-hop MTA (10.2.74.131) to use a different gateway (10.2.75.254).
hostname (config) # interface ether1 ip address 172.16.216.60 /12 hostname (config) # interface pether3 ip address 10.2.75.13 /24 hostname (config) # ip default-gateway 172.16.1.1 hostname (config) # ip route 10.2.74.130 255.255.255.255 10.2.75.254 hostname (config) # ip route 10.2.74.131 255.255.255.255 10.2.75.254
Note
If the remote MTA is on the same subnet as pether3, no static route is needed.