Using a Cisco Router

[RichH]

Hi

This is for information really.

I have just spend freeking hours trying to get a Cisco 1720 with an ethernet wic in it to work with 2mb ntl: So anyone wanting to play with a Cisco at home, this what happened.

I set it all up with NAT and was only getting outbound packets, eventully found it was an arp issue, basically you can't use the normal cisco config setting a default route to an interface rather than the next hop router address i.e. your default gateway, this results in arp request for external bound traffic being ignored.

Idealy you would want the cisco to take the default gateway from the dhcp information from ntl's dhcp server, but oh no! :mad:

So you have to work out what the default gateway is, then add

ip route 0.0.0.0 0.0.0.0 [default gateways IP]

which of cause is going to get dull when ntl think its time you got a new IP.

Anyone know of a better way round this?

Running IOS 12.1.5 on a Cisco 1720.

Cheers
Rich

[cybernetic_tiger]

I'm not a home so could not try this out but I think that the below should work. Also thought that you could use :

ip route 0.0.0.0 0.0.0.0 ethernet0

config below :


hostname Cisco1720
!
!
ip subnet-zero
no ip finger
ip dhcp excluded-address 192.168.1.1 192.168.1.10
!
ip dhcp pool lanDHCPpool
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
dns-server 194.168.4.100 194.168.8.100
!
!
!
!
!
interface Ethernet0
description WAN port to VM
ip address dhcp
ip nat outside
no ip route-cache
no ip mroute-cache
!
interface Ethernet1
description Customer LAN
ip address 192.168.1.1 255.255.255.0
ip nat inside
no ip route-cache
no ip mroute-cache
!
ip nat inside source list 1 interface Ethernet0 overload
ip classless
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip route 0.0.0.0 0.0.0.0 ethernet0
!
line con 0
exec-timeout 0 0
password cisco
logging synchronous
login
transport input none
line vty 0 4
password cisco
login
!
end

[RichH]

Thanks for that.

The problem I have is when I use....

ip route 0.0.0.0 0.0.0.0 ethernet0

I get arp problems. The router tries to arp the hosts address and doesn't get a reply.

I'm not sure if there is a command I am missing or there is some trickery built into the cheap Netgear/Linksys routers.

Rich