Solved: how do you connect a cisco router to the internet through a cable modem/ router gateway - Page 3

breynold76 · ‎04-27-2013

I have searched on here but can't find the exact answer i am looking for. I have a cisco 1760 router and a 2950 switch. The router has an ethernet wic card added so i have two ethernet connections available. I would like to connect the cable modem gatway to the router through one of the ethernet connections on the router and then to the switch. I cannot seem to get this setup to work. There are several different ways i have seen posted to accomlish this. dhcp, no dhcp, creating a seperate network, and giving the e0/0 an ip address within the range of the cable gateways network addresses. None of this has worked. Can anybody post the commands that need to be entered on the router to make this possible?

Bilal Nawaz · ‎04-28-2013

Hello Bernard, Could you please show me the outputs of:

show run

show ip route

and from the cisco router please do 'ping 8.8.8.8' and see if you get a response back.

So we know the LAN is all good! and we're saying that the magic jack phone that needs internet is working. Might be something that we've missed.

From the PC, please try to ping 'google.com'

Hope this helps

Please rate useful posts and remember to mark any solved questions as answered. Thank you.

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

breynold76 · ‎04-28-2013

ping to 8.8.8.8 was unsucsessful.

ping to google.com could not find host.

the magic jack was working and now it is not.

show run:

Router#show run

Building configuration...

Current configuration : 1345 bytes

!

! Last configuration change at 03:46:31 UTC Mon Mar 4 2002

! NVRAM config last updated at 03:43:52 UTC Mon Mar 4 2002

!

version 12.3

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

!

hostname Router

!

no logging console

!

no aaa new-model

ip subnet-zero

!

ip dhcp excluded-address 192.168.1.0 192.168.1.99

!

ip dhcp pool MY_LAN

network 192.168.1.0 255.255.255.0

dns-server 8.8.4.4 8.8.8.8

default-router 192.168.1.1

!

no ftp-server write-enable

!

interface Ethernet0/0

no ip address

shutdown

half-duplex

!

interface FastEthernet0/0

no ip address

speed auto

!

interface FastEthernet0/0.1

description ## MY LAN##

encapsulation dot1Q 1 native

ip address 192.168.1.1 255.255.255.0

ip nat inside

!

interface FastEthernet0/0.100

description ##internet##

encapsulation dot1Q 100

ip address dhcp

ip access-group MY_WAN in

!

interface Serial1/0

no ip address

shutdown

no fair-queue

!

interface Serial1/1

no ip address

shutdown

!

ip nat inside source list MY_LAN interface FastEthernet0/0.100 overload

ip classless

!

no ip http server

!

ip access-list standard MY_LAN

permit 192.168.1.0 0.0.0.255

!

ip access-list extended MY_WAN

permit tcp any any established

deny tcp any any

permit ip any any

!

line con 0

line aux 0

line vty 0 4

login

!

end

Router#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

C 192.168.1.0/24 is directly connected, FastEthernet0/0.1

Bilal Nawaz · ‎04-28-2013

Hello,

Two things I can see....

You need the 'ip nat outside' command under the interface fa0/0.100

Also, we don't seem to be getting an IP address from the modem?

Did you see an IP on the router before?

Sent from Cisco Technical Support iPhone App

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

breynold76 · ‎04-28-2013

i added the ip nat outside command to fa0/0.100.

never had an ip address from the modem.

Bilal Nawaz · ‎04-28-2013

On the switch, can you please do a 'show interface fa0/23', or whichever port the modem is connected to

And 'show run interface fa0/23'

Thank you

Sent from Cisco Technical Support iPhone App

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

breynold76 · ‎04-28-2013

Switch#show int fa0/23

FastEthernet0/23 is up, line protocol is up

Hardware is Fast Ethernet, address is 0006.2863.a4d7 (bia 0006.2863.a4d7)

Description: ## Link to Modem ##

MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive not set

Auto-duplex (Full), Auto Speed (100), 100BaseTX/FX

ARP type: ARPA, ARP Timeout 04:00:00

Last input never, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

5 minute input rate 3000 bits/sec, 5 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

69517 packets input, 7928724 bytes

Received 69516 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 39034 multicast

0 input packets with dribble condition detected

8785 packets output, 825676 bytes, 0 underruns

0 output errors, 0 collisions, 3 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out

Switch#show run int fa0/23

Building configuration...

Current configuration:

!

interface FastEthernet0/23

description ## Link to Modem ##

switchport access vlan 100

end

Bilal Nawaz · ‎04-29-2013

Hello Bernard, Everything seems to be correct now. The only problem is that we are not getting a DHCP address on the router, from the modem. Just want to do a few tests if possible?

On the router, we need to do this:

conf t

!

logging console

!

exit

!

debug ip dhcp server packet

debug ip dhcp server events

This will enable debugs on dhcp. After we have done this, could you kindly powercycle the modem wait for around 5 mins and paste the output of any debugs that might have been displayed on the screen.

The debugs we're looking for:

*Mar 1 00:06:49.123: DHCPD: IP address change on interface FastEthernet0/0

*Mar 1 00:06:49.131: DHCPD: IP address change on interface FastEthernet0/0

*Mar 1 00:06:49.135: IP: s=0.0.0.0 (local), d=255.255.255.255 (FastEthernet0/0), len 319, sending broad/multicast

*Mar 1 00:06:49.227: IP: s=10.0.0.1 (FastEthernet0/0), d=255.255.255.255, len 328, rcvd 2

*Mar 1 00:06:49.231: IP: s=0.0.0.0 (local), d=255.255.255.255 (FastEthernet0/0), len 337, sending broad/multicast

*Mar 1 00:06:49.267: IP: s=10.0.0.1 (FastEthernet0/0), d=255.255.255.255, len 328, rcvd 2

*Mar 1 00:06:50.215: %SYS-5-CONFIG_I: Configured from console by console

*Mar 1 00:06:51.107: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up

*Mar 1 00:06:52.107: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up

*Mar 1 00:06:52.275: DHCPD: IP address change on interface FastEthernet0/0

*Mar 1 00:06:52.283: DHCPD: IP address change on interface FastEthernet0/0

*Mar 1 00:06:53.363: %DHCP-6-ADDRESS_ASSIGN: Interface FastEthernet0/0 assigned DHCP address 10.0.0.2, mask 255.255.255.0, hostname R2

After this is done, you can go ahead and do the 'no logging console' command to stop the logging displaying on your console session.

Thank you.

Please rate useful posts and remember to mark any solved questions as answered. Thank you.

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

Richard Burts · ‎04-29-2013

I would like to ask again how the router is connected to the cable modem. I am not clear if it has changed since I asked that before.

If the recent suggestions about debugging for DHCP do not get us to a solution I would suggest dropping the subinterfaces - at least for now. I would like to try configuring just the FastEthernet interface to use DHCP to get an address. I still believe that the biggest problem is something between the router and the cable modem. I would like to get that solved. After that is working we can fix issues with the switch and can decide whether router on a stick is the optimum solution.

HTH

Rick

HTH

Rick

Bilal Nawaz · ‎04-29-2013

Agreed, however I believe that it was better to take the e0/0 out of the equation and not waste any time tackling this problem. Bernard has correctly configured the router and the switch for router on a stick. LAN is OK. We know router on a stick works.

And as we already know, the problem is with the modem. The router is fine and the interface is working.

All interfaces are operating at 100mb full duplex.

So we need to work out why the modem is not behaving. I know with some ISPs they require authentication, not sure if this is the case.

Sent from Cisco Technical Support iPhone App

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

breynold76 · ‎04-29-2013

The router is connected to the cable modem with a 35ft cat6 A stp cable. The cable does work because if i connect it directly to the computer i get a fast solid internet connection. I have switched around the cables on the back of the modem/router gateway to try different ports. On this gateway there is only the coax cable input and 4 ethernet connections, no wan port. The modem/router gateway is a motorola sbg6580.

breynold76 · ‎04-29-2013

R1#

Mar 4 20:59:52.885: DHCPD: checking for expired leases.

Mar 4 21:01:05.624: DHCPD: DHCPREQUEST received from client 0164.8099.1392.50.

Mar 4 21:01:05.624: DHCPD: client has moved to a new subnet.

Mar 4 21:01:05.624: DHCPD: Sending DHCPNAK to client 0164.8099.1392.50.

Mar 4 21:01:05.624: DHCPD: broadcasting BOOTREPLY to client 6480.9913.9250.

Mar 4 21:01:05.644: DHCPD: DHCPDISCOVER received from client 0164.8099.1392.50 on interface FastEthernet0/0.100.

Mar 4 21:01:05.644: DHCPD: there is no address pool for 0.0.0.0.

Mar 4 21:01:05.656: DHCPD: DHCPREQUEST received from client 0164.8099.1392.50.

Mar 4 21:01:09.847: DHCPD: DHCPINFORM received from client 0164.8099.1392.50 (192.168.0.5).

Mar 4 21:01:12.848: DHCPD: DHCPINFORM received from client 0164.8099.1392.50 (192.168.0.5).

Mar 4 21:01:52.886: DHCPD: checking for expired leases.

Mar 4 21:02:11.324: DHCPD: DHCPDISCOVER received from client 0100.14d1.e8b5.9e on interface FastEthernet0/0.100.

Mar 4 21:02:11.324: DHCPD: there is no address pool for 0.0.0.0.

Mar 4 21:02:11.336: DHCPD: DHCPREQUEST received from client 0100.14d1.e8b5.9e.

Mar 4 21:02:12.301: DHCPD: DHCPINFORM received from client 01f4.6d04.9da7.72 (192.168.0.4).

Mar 4 21:02:15.302: DHCPD: DHCPINFORM received from client 01f4.6d04.9da7.72 (192.168.0.4).

Mar 4 21:02:17.634: DHCPD: DHCPINFORM received from client 0100.14d1.e8b5.9e (192.168.0.6).

Mar 4 21:02:20.635: DHCPD: DHCPINFORM received from client 0100.14d1.e8b5.9e (192.168.0.6).

Mar 4 21:02:49.022: DHCPD: DHCPINFORM received from client 0164.8099.1392.50 (192.168.0.5).

Mar 4 21:02:52.023: DHCPD: DHCPINFORM received from client 0164.8099.1392.50 (192.168.0.5).

Mar 4 21:03:26.303: DHCPD: DHCPINFORM received from client 01f4.6d04.9da7.72 (192.168.0.4).

Mar 4 21:03:29.304: DHCPD: DHCPINFORM received from client 01f4.6d04.9da7.72 (192.168.0.4).

Mar 4 21:03:37.321: DHCPD: DHCPINFORM received from client 0100.14d1.e8b5.9e (192.168.0.6).

Mar 4 21:03:40.318: DHCPD: DHCPINFORM received from client 0100.14d1.e8b5.9e (192.168.0.6).

Mar 4 21:03:52.886: DHCPD: checking for expired leases.

Mar 4 21:04:54.183: DHCPD: DHCPINFORM received from client 01f4.6d04.9da7.72 (192.168.0.4).

Mar 4 21:04:57.184: DHCPD: DHCPINFORM received from client 01f4.6d04.9da7.72 (192.168.0.4).

Mar 4 21:05:04.768: DHCPD: DHCPINFORM received from client 0100.14d1.e8b5.9e (192.168.0.6).

Mar 4 21:05:07.765: DHCPD: DHCPINFORM received from client 0100.14d1.e8b5.9e (192.168.0.6).

Mar 4 21:05:52.887: DHCPD: checking for expired leases.

Mar 4 21:06:24.379: DHCPD: DHCPINFORM received from client 0164.8099.1392.50 (192.168.0.5).

Mar 4 21:06:27.380: DHCPD: DHCPINFORM received from client 0164.8099.1392.50 (192.168.0.5).

Mar 4 21:07:52.888: DHCPD: checking for expired leases.

Bilal Nawaz · ‎04-29-2013

Hello Bernard,

Im really interested in what these messages are?

Mar 4 21:01:05.644: DHCPD: DHCPDISCOVER received from client 0164.8099.1392.50 on interface FastEthernet0/0.100

Mar 4 21:01:05.644: DHCPD: there is no address pool for 0.0.0.0

Why are we getting a query on this interface when we should be getting offers instead?

Which leaves me to believe you have things cabled up the wrong way...

Can we do this please?

From the Motorola use ethernet port 1 - connect this to the switch on fa0/23

The configuration of this interface should be the same

Switch#show run int fa0/23

Building configuration...

Current configuration:

!

interface FastEthernet0/23

description ## Link to Modem ##

switchport access vlan 100

end

From the Router use fa0/0 - connect this to the switch on fa0/24

I also noticed that the address range 192.168.0.X is in use instead of the 192.168.1.X? Is this correct?

Hope this helps.

Please rate useful posts and remember to mark any solved questions as answered. Thank you.

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

breynold76 · ‎04-29-2013

that is how i have it connected. motorola>fa0/23 and fa0/24>fa0/0 on router.

the address range 192.168.0.x is what is given out by the motorola.

Bilal Nawaz · ‎04-29-2013

That's so strange...

Could we try this....

On the router:

Conf t

!

no interface fa0/0.1

no interface fa0/0.100

!

interface fa0/0

ip address DHCP

Plug the modem directly into fa0/0 on the router and then see if you pick up an IP address.

Thank you

Please rate useful posts and remember to mark any solved questions as answered. Thank you.

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

breynold76 · ‎04-29-2013

R1#config t

Enter configuration commands, one per line. End with CNTL/Z.

R1(config)#no int fa0/0.1

Not all config may be removed and may reappear after reactivating the sub-interface

R1(config)#no int fa0/0.100

Not all config may be removed and may reappear after reactivating the sub-interface

R1(config)#int fa0/0

R1(config-if)#ip address dhcp

R1#show ip int brief

Interface IP-Address OK? Method Status Protocol

Ethernet0/0 unassigned YES TFTP administratively down down

FastEthernet0/0 unassigned YES DHCP up up

FastEthernet0/0.1 unassigned YES manual deleted down

FastEthernet0/0.100 unassigned YES DHCP deleted down

Serial1/0 unassigned YES TFTP administratively down down

Serial1/1 unassigned YES TFTP administratively down down