Cisco 1720 1ENET WIC + DSL

[rbanke]

Hello, It's been a long time since I had to do any work on routers and for some reason I cant get this working (memory/old age, or both) so I am appealing to some good natured souls for some help

I have a 1720 with an 1ENET WIC which i would like to connect a zyxel 660 DSL modem to as the internet connection. The service is embarq and they use enet encap not pppoe. I have tried several things and i cant seem to get the router to communicate properly. When setting the modem in bridge mode, and the wic to DHCP, the router does not recieve an IP. If i leave the dsl modem in routing mode, with the DHCP service left on, the router will indeed recieve a modem specified ip. While having the modem in bridge mode, I have also tried manually setting the wic's ip to the ip the router would give a pc client and that also does not work.

If someone could give me a kick in the right direction, or even post a sample config, that would help a ton.

Thanks
-Rich

 

[burtsbees]

With the modem in routing mode and the router's wic set to dhcp, does it still not work? Do you have a default route set? Does the modem NAT? If not, you need to configure the router to NAT. Is this DSL? I am unfamiliar with what you have posted...

Burt

 

[rbanke]

Thanks for the reply Burt!

Yes it is DSL. One of the configurations I did try was to leave the modem setup as it came which was routing mode, nat enabled, dhcp enabled. When I set the router's wic to dhcp it DID gain an ip from the DSL modem however when I set my default route to point to the wic's interface, no clients could reach the internet. If that is the proper way to set it up, I can go back to that setting and then go from there. I mainly want to make sure I start out in the right direction.

Thanks again
-Rich

 

[burtsbees]

What IP and mask did the WIC get? I have had problems when I have done this because the stupid modem I have gave me 192.168.x.x with a 255.255.0.0 mask, which is a supernet! Otherwise, please post a sh run from the router.

Burt

 

[plshlpme]

when you put your modem in router mode did it have an ip statically assigned for the isp?

basically when there is no pppoe you have a lan extension as the telco has built you a permanent pvc and eliminated the need for the pppoe so you shouldnt need anything fancy in your router to get the link up..

the router will treat it just as an ethernet interface.

i just wanted to make sure that you werent assigned statically and maybe there is no dhcp on your isp side for your link...

 

[rbanke]

Plshlbme, the public ip of the dsl modem is not static. If i remember correctly, when the dsl modem is in bridge mode it should pass the public ip to whatever is connected to the dsl modem ethernet port, right? While the dsl modem was in bridging mode, I could connect a laptop to its ethernet port and the laptop would gain a public ip, however when connecting the router's wic to the dsl modem's ethernet port, and set the wic to use dhcp, the cisco router would not gain an ip. Manually setting the information did not work either. Going to try some stuff based on both posts and see where it takes me today.

Thanks
-Rich

 

[plshlpme]

yeah your correct. the modem does the ATM portion of the connection and leaves you with the ethernet portion.

so with the modem bridged you should be able to go with

ip address dhcp ??

set your interface to 10 half probably for the modem as well ?

does your isp have a longer lease time where maybe they have the mac of your laptop and wont let you put the router on? the cable telco up here used to do that..

 

[rbanke]

This is a sh run and sh int with the dsl modem in bridge mode. I can plug the dsl modem into my laptop and recieve the public ip, however as you can see the ethernet interface does not. I checked on the modem and there does not seem to be a way to force 10/half.

sh run
Building configuration...

Current configuration : 1156 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname winterpark
!
boot system flash c1700-k9o3sy7-mz.122-11.t10.bin
boot system flash
enable password 7 15180A0E547E7B777D61347A
!
memory-size iomem 25
ip subnet-zero
!
!
no ip domain lookup
!
ip audit notify log
ip audit po max-events 100
!
--More--  !
!
!
!
interface Ethernet0
ip address dhcp
half-duplex
!
interface FastEthernet0
description connected to Cisco1538
ip address 192.168.4.1 255.255.255.0
ip helper-address 192.168.1.40
speed auto
!
interface Serial0
ip address 192.168.3.2 255.255.255.252
ip helper-address 192.168.1.40
!
interface Serial1
no ip address
shutdown
!
router rip
--More--   version 2
network 192.168.3.0
network 192.168.4.0
network 192.168.6.0
no auto-summary
!
ip classless
ip route 0.0.0.0 0.0.0.0 Ethernet0
no ip http server
!
!
!
snmp-server engineID local 00000009020000B0C2882EEB
snmp-server community public RO
snmp-server enable traps tty
!
line con 0
exec-timeout 0 0
password 7 141D13095C507A78717A326D
login
line aux 0
line vty 0 4
password 7 141D13095C507A78717A326D
--More--   login
!
no scheduler allocate
end

winterpark#sh int e0
Ethernet0 is up, line protocol is up
Hardware is PQUICC Ethernet, address is 001a.6d72.7e70 (bia 001a.6d72.7e70)
Internet address will be negotiated using DHCP
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 10BaseT
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:06:57, output 00:00:02, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue :0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
150 packets input, 12894 bytes, 0 no buffer
Received 11 broadcasts, 0 runts, 0 giants, 0 throttles
240165 input errors, 0 CRC, 0 frame, 0 overrun, 240165 ignored
0 input packets with dribble condition detected
241282 packets output, 29346454 bytes, 0 underruns
240166 output errors, 0 collisions, 4 interface resets
0 babbles, 0 late collision, 0 deferred
--More--   240166 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
winterpark#

 

[rbanke]

Also, With the dsl modem in routing mode, the cisco router will gain an ip from the modem. I can ping to the internet using the router however, clients cannot.

 

[plshlpme]

when you plug in your laptop what settings does the interface auto negotiate?

i have a newer dsl modem at home that only syncs at 100mb... its a black speedstream.. you may want to try configuring it to sync on your fast ethernet port as a test..

im sure when in router mode that your router is missing some nat statememnts and that is why your clients cant browse the web.. basically your cisco will nat to the ip that the modem assigned you.. and then the modem will nat again to the public ip.. double natting is not ideal.. unless your able to add a static ip for your lan subnet in the modem ?