Router & Firewall Operation

[cisconoobie]

Can someone tell me exactly how a router and firewall work in this example.

Router connects to internet

Firewall connects to router

Router has IP range 10.0.0.0/26

Firewall outside interface is 10.0.0.3

Firewall also has some Nat policies for some 10.0.0.0/26 IPs that translate to internal IPs

Now my question is does the Router send Arp requests to the firewall and does the firewall respond? Does the firewall check its NAT table ? How does this oepration work, anyone can explain ?

[Jon Marshall]

Hi

The firewall runs proxy arp and will respond to arp requests from the router for hosts that it has a static mapping for.

Attached is a link that explains it in more detail. Have a look at no 8 under "Troubleshoot Connectivity Problems"

http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_tech_note09186a008009402f.shtml#trouble

HTH

Jon