Setting up NAT

is routing set up correctly ... is there a default route toward your isp?

BernieM

Cisco 2621 Router:
    2 Fast Ethernet
    2 WIC module slots (1 with serial card)
    1 AIM module slot

Cisco 1602 Router:
    1 Ethernet
    1 Serial

NAT:
This assumes that the 2621 is using FastEthernet 0/0 to the cablemodem =
and FastEthernet 0/1 to your inside network with Serial 0 going to the =
1602 with another Ethernet network behind it.
  config terminal

  interface FastEthernet 0/0
   description Connection to Cable Modem
   ip address dhcp
   ip nat outside

  interface FastEthernet 0/1
   description Connection to Inside LAN
   ip nat inside

  interface Serial 0
   description Connection 1602 Router Serial 0
   ip nat inside

  ip access-list standard ip_nat_range
   permit 10.0.0.0 0.255.255.255
   permit 172.16.0.0 255.224.0.0
   permit 192.168.0.0 255.255.0.0

  ip nat inside source list ip_nat_range interface FastEthernet 0/0 =
overload

  end
The IP address ranges in that access-list are just my example which =
covers all RFC1918 private IP addresses.
Make sure your routing is good as mentioned in the previous reply.
  router rip
   version 2
   network 10.0.0.0
   network 172.16.0.0
   network 192.168.0.0
   passive-interface FastEthernet 0/0
   redistribute connected
Correct routing will make sure the downstream 1602 can connect.  Fool =
around with the use of "redistribute connected" and the use of both =
"redistribute static" and making a static default route to the next hop =
router from your ISP.
Example:
  ip route 0.0.0.0 0.0.0.0 w.x.y.z
Salutaitons,
Lord Balki
1 test remaining for CCNP