Running Cable Broadband with a cisco 1720 1

[bussche]

I am trying to setup my Cisco 1720 with 2 ethernet interfaces to connect to the internet via a Motorola Surfboard cable modem.
Basically the setup is I have Ethernet0 connected to my cable modem and FastEthernet0 running to the switch for the LAN. From what I remember I should just have to setup a static route so that any traffic coming from the lan is shot out to the Wan network, and any traffic coming from the Wan is shot back into the Lan network. I was doing some reading on the internet and I configure PAT as well to translate all the internal Lan ip’s to that external wan Ip.

From a host on the inside I can ping the routers internal 192.168.1.3 interface as well as the external 216.36.150.18 interface but not the 216.36.150.18 wan gateway.

Is there another step I’m missing? Here is my config:



User Access Verification
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname yr
!
enable secret (removed)
enable password (removed)
!
memory-size iomem 25
ip subnet-zero
!
!
!
!
interface Ethernet0
ip address 216.36.150.18 255.255.255.0
ip nat outside
half-duplex
!
interface FastEthernet0
ip address 192.168.1.3 255.255.255.0
ip nat inside
speed auto
half-duplex
no cdp enable
!
ip nat inside source list 1 interface Ethernet0 overload
ip classless
ip route 0.0.0.0 0.0.0.0 216.36.150.1
ip route 216.36.150.0 255.255.255.0 FastEthernet0
no ip http server
!
!
access-list 1 permit 192.168.1.0 0.0.0.255
dialer-list 1 protocol ip permit
dialer-list 1 protocol ipx permit
!
line con 0
line aux 0
line vty 0 4
password (removed)
login
!
end


Any Ideas? Thanks in advance, I appreciate any insight.

 

[IPKONFIG]

YES, if your modem is bridging. This is very important. If your modem is performing NAT of any kind then it's not briding the traffic. This is what BurtsBee was talking about in his post.

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[bussche]

Ok thanks, I'll have to wait till after office hours to test the config, but ya I was just confused because of what was suggested earlier.

 

[bussche]

No, I cannot ping 216.36.150.1

 

[burtsbees]

If your modem does do the NAT, then just do the
ip add dhcp
no shut
on the interface that connects to it. I suggested that the modem was not bridging because it appears to be doing the PPPoE/PPPoA negotiations and authentication, since it does have an IP address...if the modem bridges, then you likely need a vpdn and dialer config in the router to do the PPPoE/PPPoA.

Burt

 

[bussche]

I am going to try the dhcp, but I don't think i will need the vpdn or dialer as its not using ppoe.

 

[burtsbees]

What authentication is it using?

Burt

 

[bussche]

I don't think it is using any, when you use the cable connection with a off the shelf consumer level router you do not need to use any login information.

 

[supatech]

Your cable modem is a bridge and is not doing any nat.

as far as your addressing I would bet money they have a dhcp reservation for your static. Meaning you will not assign it to your interface (ip address dhcp)If its not dhcp then your subnet mask IS wrong, would be something like 255.255.255.252 depends on how many ip they reserved for you. I would call and ask.

Cable uses mac address auth (usually the one on the cable modem) so thats not something you should even look at.

I did not see any routing protocol, you can use static routes for everything but I would enable rip

router rip
version 2
network
10.0.0.0
192.168.1.0

ip route 0.0.0.0 0.0.0.0 216.36.150.1 /this should work as long as its your next hop address your cable modem will not have an address assigned except for administration (192.168.100.1)

leave access-list 1 permit 192.168.1.0 0.0.0.255 with nat only specify networks you are using I would not leave it 0.0.0.0

interface Ethernet0 --change this to your cable modem as this is only an 10Mb ethernet port
ip address 216.36.150.18 255.255.255.0
ip nat outside
half-duplex - just remove this
!
interface FastEthernet0 - change this to your inside as this is 100Mb ethernet port
ip address 192.168.1.3 255.255.255.0
ip nat inside
speed auto
half-duplex - remove this
no cdp enable

I am assuming ethernet 0 and ethernet 1 are 10Mb WIC cards

http://www.cisco.com/warp/public/109/router_behind_cm_19268.shtml

CCNA MCSE MCP NET+ A+ Security+