Force routing using a secondary IP as its source

[noticketnomas]

Hello,

Is it possible to force a router to use its secondary IP on an outside-facing interface as a source IP for traffic that originates from within the router, such as ICMP, NTP, and DNS?

i.e.

interface vlan 200

ip address 10.0.0.2 255.255.255.0

ip address 12.12.12.2 255.255.255.252 secondary

ip route 0.0.0.0 0.0.0.0 12.12.12.1

Every time I try to ping a public network, the router defaults to using 10.0.0.2 as its source, which obviously goes nowhere.  And before you ask, yes I'm stuck with 10.0.0.2 as my primary IP for reasons not listed

Thanks,

Wil

[John Blakley]

Wil,

Cisco routers always source from the primary address. Is the secondary address a public address or is this something on your network?

John

[noticketnomas]

Primary is private, secondary is public.

[John Blakley · Accepted solution]

I have to say, generally you won't run a private/public addresses on the same interface. Unfortunately you won't be able to source your 12.x.x.x traffic as the source packet unless you reverse the 2 addresses on the interface.

John

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