2500 NOT OBTAINING IP ADDRESS FROM CABLE MODEM

[Tigerjoe]

Hi,
I have a 2514 router with two ethernet ports. Iam connecting a cable modem to one port and the other port is going to be hooked up to my LAN. I have configured my WAN port with IP ADDRESS DHCP. For some reason my WAN port will not obtain an IP address from the ISP. I have forced a MAC address to that port but that wouldnt be the case since I can plug in the cable modem to any PC in the house and they will obtain IP address'. Iam running 12.1(T) IOS.

!
version 12.2
no parser cache
no service pad
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname XXXX
!
enable secret 5 $1$9znJ$GeUXEK6BSoN1
!
ip subnet-zero
ip name-server 24.x.x.x
ip dhcp excluded-address 10.10.10.1
ip dhcp excluded-address 10.10.10.2
ip dhcp excluded-address 10.10.10.3
ip dhcp excluded-address 10.10.10.4
ip dhcp excluded-address 10.10.10.5
!
ip dhcp pool client
import all
network 10.10.10.0 255.255.255.0
default-router 10.10.10.1
dns-server 24.x.x.x
!
!
!
!
interface Ethernet0
ip address 10.10.10.1 255.255.255.0
ip nat inside
no ip route-cache
no ip mroute-cache
no cdp enable
!
interface Ethernet1
ip address dhcp
ip nat outside
no ip route-cache
no ip mroute-cache
no cdp enable
!
interface Serial0
no ip address
shutdown
no fair-queue
!
interface Serial1
no ip address
shutdown
!
ip nat inside source list 102 interface Ethernet1 overload
ip classless
ip route 0.0.0.0 0.0.0.0 65.x.x.1
ip http server
!
!
access-list 102 permit ip 10.10.10.0 0.0.0.255 any
!
line con 0
exec-timeout 120 0
stopbits 1
line aux 0
line vty 0 4
exec-timeout 30 0
login local
length 0
!
end

Thanks for any suggestions.

 

[jamin123]

This is a basic working Config for a 2514. You may want to turn of http on your router.


ip dhcp pool CLIENT
network 10.0.0.0 255.0.0.0
default-router 10.0.0.1
dns-server 10.0.0.9
ip domain-name com2jesus.com
!
!
!
!
interface Ethernet0
ip address 10.0.0.1 255.0.0.0
ip nat inside

!
interface Ethernet1
description cable-modem0
ip address dhcp
ip nat outside
!
ip nat inside source list 102 interface Ethernet1 overload
ip classless

!
access-list 102 permit ip 10.0.0.0 0.0.0.255 any
ip route 0.0.0.0 0.0.0.0 168.10.76.1

 

[Tigerjoe]

Hi, I just tried that configuration but I still have the same problem.

when i put the command IP ADDRESS DHCP,

i get the following error.

*Mar 1 00:17:23.511: %IP-4-CLASS: Bad IP address and mask 0.0.0.0/0 in class_resolve()

 

[Tigerjoe]

I searched cisco.com for that error and this is what i got.

Error Message
%IP-4-CLASS: Bad IP address [inet] and mask [inet]
in class_resolve()%IP-3-DESTHOST: src=[inet], dst=[inet], NULL desthost
Explanation An internal software error occurred.

Recommended Action If either of these messages recur, call your technical support representative for assistance.

If anyone has any better suggestions, let me know please

 

[wybnormal]

The first rule when troubleshooting something like this is to remove EVERYTHING that doesnt apply to what it is that you are trying to fix. In this case, for now, dump the DHCP server.. just hard code the IP address for the router's LAN port and the client or even better is to just console in so you dont need Ip to work right now. Dump NAT, Dump routes etc.. just enable the outside interface facing the WAN and configure the DHCP client piece AND mac address if needed. Once that works, then add one piece at a time.

When you start making wholesale changes to the router config (or server etc), it makes it very hard to troubleshoot sine many times you do not exactly what is the problem and where it is..

I would get DHCP working as the client, then routing, then DHCP server and NAT would be the last item since you would need to change a couple of things.

Also, why have you turned of ip route cache? that has a high effect on the router's CPU utilization. Not that it matters much in this case, but it's a bad habit to get into unless absolutely required. And the only real reason is to enable per packet routing instead of per destination routing which is the default.

MikeS
Find me at

http://www.packetattack.com

"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu

 

[Tigerjoe]

Well... I turned off ip route cache because i was doing a step by step thing from cisco. I also tried the sample config from your site (

http://www.packetattack.com)

and i got the same result. And now I did

Router#erase startup-config

reloaded to just start from scratch.


Current configuration : 434 bytes
!
version 12.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
!
ip subnet-zero
!
!
!
!
interface Ethernet0
no ip address
shutdown
!
interface Ethernet1
ip address dhcp
!
interface Serial0
no ip address
shutdown
no fair-queue
!
interface Serial1
no ip address
shutdown
!
ip classless
ip http server
!
!
!
line con 0
line aux 0
line vty 0 4
!
end


Even now when i do

Router#sho in e1

Ethernet1 is up, line protocol is up
Hardware is Lance, address is 00e0.b064.0431 (bia 00e0.b064.0431)
Internet address will be negotiated using DHCP
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
etc... etc...

Any suggestions??

 

[jamin123]

What version IOS are you using? Earlier version doesn't support DHCP.

I once use a sample config from cisco site but I can't find it so look at this link.

http://www.cisco.com/warp/public/109/config_nat_on_cm.html

 

[jamin123]

Your erro means that your IP is not in your subnet rage.

I add some explanation to the below config. Hope that helps.


RouterP#sh run
Building configuration...

!
version 12.2
!
hostname
!
!
ip subnet-zero
ip dhcp excluded-address 10.0.0.1 (int e0 to my LAN)
!
ip dhcp pool CLIENT
network 10.0.0.0 255.0.0.0
(I've a 10.0.0.0 network on a 255.0.0.0 sutbnet)
default-router 10.0.0.1 (int e0 to LAN)
dns-server 10.0.0.9 (DNS server)
!
!
!
!
interface Ethernet0
ip address 10.0.0.1 255.0.0.0 (int e0 to LAN)
ip nat inside
no ip route-cache
no ip mroute-cache
!
interface Ethernet1
description cable-modem0
ip address dhcp
ip nat outside
no ip route-cache
no ip mroute-cache
!
ip nat inside source list 102 interface Ethernet1 overload
ip classless
ip route 0.0.0.0 0.0.0.0 68.100.176.1
(68.100.176.1 cable modem IP. I got it by #sh ip interface brief)
no ip http server
ip pim bidir-enable
!
access-list 102 permit ip 10.0.0.0 0.0.0.255 any
(This permit all traffic from 10.0.0.0 network)
!
line con 0
line aux 0
transport input all
line vty 0 4
login
!
end

RouterP#

 

[wybnormal]

One *trick* you can try as a troublesooting aid is this.. hook your workstation/laptop/something to the line and get an address. Make a note of the IP address/subnet mask AND the mac address. Install the router and use this IP AND mac address for the WAN port. It *should* come up since it's all static at this point. Now we have verified that the router/WAN will in fact work together and the issue is with the DHCP serving the IP.

I did find this on the CCO

::snip::
Some ISPs require that the DHCPDISCOVER message have a specific host name and client identifier that is the MAC address of the interface. The most typical usage of the ip address dhcp client-id interface-name hostname host-name command is when interface-name is the Ethernet interface where the command is configured and host-name is the host name provided by the ISP.

A client identifier (DHCP option 61) can be a hexadecimal or an ASCII value. By default, the client identifier is an ASCII value. The client-id interface option overrides the default and forces the use of the hexadecimal MAC address of the named interface.
::snip::

This might explain your problem?

Here is the original text:

http://www.cisco.com/en/US/products...ference_chapter09186a0080087376.html#xtocid14

MikeS
Find me at

http://www.packetattack.com

"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu

 

[Tigerjoe]

I did exactly the way you said, but the router was still not able to get an IP address from the cable modem. It will get an IP address if i connect it to another DHCP server. The thing is that if I connect the cable modem to different pc's around the house they get ip address'. So does my netgear router. But my cisco router just wont get the ip address from the cable modem. BTW Iam running 12.2(T)IOS on 16f/16d just in case that might help any.

Router(config-if)#shutdown
Router(config-if)#
*Mar 1 00:14:33.451: %IP-4-CLASS: Bad IP address and mask 0.0.0.0/0 in class_resolve()

But I get this error only after putting the command IP ADDRESS DHCP, right after i shut down the interface. Thats the only time it happens.

 

[Tigerjoe]

Mike iam supposed to have dynamic ip, but the last time they change my ip was more than a year ago. I dont think that the mac address would have anything to do with it, since i plug in other pc's directly to the cable modem and they all connect fine.

 

[wybnormal]

Error Message
%IP-4-CLASS: Bad IP address and mask [int][inet] in class_resolve()

Explanation An internal software error has occurred.

Recommended Action Copy the error message exactly as it appears on the console or in the system log, call your Cisco technical support representative, and provide the representative with the gathered information.

This sounds ominous doesnt it? At this point I might guess at a corrupted IOS load.. or a bug. Is there any way you can bump up the rev level of your code?

What is the exact code you have? the file name of the code can give a clue so a show version is in order.

MikeS
Find me at

http://www.packetattack.com

"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu

 

[Tigerjoe]

I hope the IOS is not the problem because i went through a lot just to get the file.

Router#sho ver
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-I-L), Version 12.2(11)T, RELEASE SOFTWARE (fc1)
TAC Support:

http://www.cisco.com/tac

Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Thu 01-Aug-02 21:19 by ccai
Image text-base: 0x03052264, data-base: 0x00001000

ROM: System Bootstrap, Version 5.2(8a), RELEASE SOFTWARE
BOOTLDR: 3000 Bootstrap Software (IGS-RXBOOT), Version 10.2(8a), RELEASE SOFTWAR
E (fc1)

Router uptime is 2 minutes
System returned to ROM by power-on
System image file is "flash:c2500-i-l.122-11.T.bin"

cisco 2500 (68030) processor (revision L) with 14336K/2048K bytes of memory.
Processor board ID 05689184, with hardware revision 00000000
Bridging software.
X.25 software, Version 3.0.0.
2 Ethernet/IEEE 802.3 interface(s)
2 Serial network interface(s)
32K bytes of non-volatile configuration memory.
16384K bytes of processor board System flash (Read ONLY)

 

[Tigerjoe]

BTW I only get that error when its connected to the cable modem not when its connected to any other dhcp server.