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New Member

DHCP Issue with ISP on Cisco 2621XM

Hello,

I have a Cisco 2121XM running IOS Version 12.4(17).  I have tried every way I know how to get DHCP to work with my local ISP.  I have TDS Telecom “fiber”, it’s not an actual fiber line coming in but there is no modem.  I connect the Cat5 into the Cisco router and it will not obtain an IP address.

I have connected non-cisco routers and they all obtain without problem, even straight into my laptop.  The IP address is not static, but it has a very long lease time because I can have the same IP for months.  However, even setting static IP on the Cisco router, it was unable to connect to TDS.  I’ve even tried spoofing the mac-address just in case they were blocking the cisco equipment.  Any suggestions would be greatly appreciated.

Steps I’ve attempted

1) Using a crossover from TDS line to Cisco router

2) Updated IOS version

3) Spoofed mac-address

4) Cleared all configs and started from scratch

Below is my running-config I am using,

Thank you again for any suggestions.

  1. Building configuration...
  2. Current configuration : 707 bytes
  3. !
  4. version 12.4
  5. service timestamps debug datetime msec
  6. service timestamps log datetime msec
  7. no service password-encryption
  8. !
  9. hostname WadeRouterOne
  10. !
  11. boot-start-marker
  12. boot system flash:c2600-ipbasek9-mz.124-17.bin
  13. boot-end-marker
  14. !
  15. enable secret 5 $1$dFUQ$Z69xuuyPohIq1mc.uANlS.
  16. !
  17. no aaa new-model
  18. memory-size iomem 15
  19. no network-clock-participate slot 1
  20. no network-clock-participate wic 0
  21. ip cef
  22. !
  23. !
  24. !       
  25. !       
  26. !       
  27. !       
  28. !       
  29. !       
  30. !       
  31. !       
  32. !       
  33. interface FastEthernet0/0
  34. ip address dhcp
  35. duplex auto
  36. speed auto
  37. !       
  38. interface FastEthernet0/1
  39. no ip address
  40. shutdown
  41. duplex auto
  42. speed auto
  43. !       
  44. ip forward-protocol nd
  45. !       
  46. ip http server
  47. no ip http secure-server
  48. !       
  49. !       
  50. control-plane
  51. !       
  52. !       
  53. line con 0
  54. line aux 0
  55. line vty 0 4
  56. login   
  57. !       
  58. !       
  59. end
8 REPLIES
Green

DHCP Issue with ISP on Cisco 2621XM

Lewis,

Can you try a debug

debug dhcp detail

this should show the dhcp send & recive packets and may give a clue as to where things are wrong.

Regards,
Alex.
Please rate useful posts.

Regards, Alex. Please rate useful posts.
Cisco Employee

DHCP Issue with ISP on Cisco 2621XM

Hello ,

Nice suggestion given by Alex to see the debugs. I would like add a following point :-

1. Try to put static ip address on the fa interface and see if it works.

2. Static ip will be the same which is Acquired on the laptop.

3.try to change the port.

4.Mac address can be registered by telco , which can either be cleared by reloading the modem device or can be flused upon calling your provider.

5. Try to shut the port , reload the modem and unshut it.

6. Share the debugs.

-Ashish Arora

Purple

DHCP Issue with ISP on Cisco 2621XM

Hi,

I have TDS Telecom “fiber”, it’s not an actual fiber line coming in but  there is no modem.  I connect the Cat5 into the Cisco router and it will  not obtain an IP address. 

If you've got no modem how are you connected to your ISP ? Is it DSL or Cable provider ?

Can you explain a little bit more.

Regards

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.
New Member

DHCP Issue with ISP on Cisco 2621XM

Thank you for your reply... attached is the DEBUG DHCP

FastEthernet0/0 is up, line protocol is up

  Hardware is AmdFE, address is 000b.5f53.0740 (bia 000b.5f53.0740)

  Internet address will be negotiated using DHCP

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

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

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 100Mb/s, 100BaseTX/FX

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

  Last input never, output 00:00:03, 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

     0 packets input, 0 bytes

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

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

     0 watchdog

     0 input packets with dribble condition detected

     6264 packets output, 1381052 bytes, 0 underruns

     0 output errors, 0 collisions, 50 interface resets

     0 unknown protocol drops

     0 babbles, 0 late collision, 0 deferred

     321 lost carrier, 0 no carrier

     0 output buffer failures, 0 output buffers swapped out

--DHCP log

*Jan 11 10:26:06.545: DHCP: DHCP client process started: 10

*Jan 11 10:26:06.549: DHCP: Waiting for 5 seconds on interface FastEthernet0/0 to come up

*Jan 11 10:26:08.537: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up

*Jan 11 10:26:11.049: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up

*Jan 11 10:26:11.549: RAC: Starting DHCP discover on FastEthernet0/0

*Jan 11 10:26:11.549: DHCP: Try 1 to acquire address for FastEthernet0/0

*Jan 11 10:26:11.561: DHCP: allocate request

*Jan 11 10:26:11.561: DHCP: new entry. add to queue, interface FastEthernet0/0

*Jan 11 10:26:11.561: DHCP: SDiscover attempt # 1 for entry:

*Jan 11 10:26:11.565: Temp IP addr: 0.0.0.0  for peer on Interface: FastEthernet0/0

*Jan 11 10:26:11.565: Temp  sub net mask: 0.0.0.0

*Jan 11 10:26:11.565:    DHCP Lease server: 0.0.0.0, state: 1 Selecting

*Jan 11 10:26:11.565:    DHCP transaction id: 15EC

*Jan 11 10:26:11.565:    Lease: 0 secs,  Renewal: 0 secs,  Rebind: 0 secs

*Jan 11 10:26:11.565:    Next timer fires after: 00:00:04

*Jan 11 10:26:11.565:    Retry count: 1   Client-ID: cisco-000b.5f53.0740-Fa0/0

*Jan 11 10:26:11.565:    Client-ID hex dump: 636973636F2D303030622E356635332E

*Jan 11 10:26:11.565:                        303734302D4661302F30

*Jan 11 10:26:11.569:    Hostname: WadeRouterOne

*Jan 11 10:26:11.569: DHCP: SDiscover: sending 302 byte length DHCP packet

*Jan 11 10:26:11.569: DHCP: SDiscover 302 bytes

*Jan 11 10:26:11.569: IP: s=0.0.0.0 (local), d=255.255.255.255 (FastEthernet0/0), len 604, sending broad/multicast

*Jan 11 10:26:11.569:     UDP src=68, dst=67

*Jan 11 10:26:11.569:             B'cast on FastEthernet0/0 interface from 0.0.0.0

*Jan 11 10:26:14.949: DHCP: SDiscover attempt # 2 for entry:

*Jan 11 10:26:14.949: Temp IP addr: 0.0.0.0  for peer on Interface: FastEthernet0/0

*Jan 11 10:26:14.949: Temp  sub net mask: 0.0.0.0

*Jan 11 10:26:14.949:    DHCP Lease server: 0.0.0.0, state: 1 Selecting

*Jan 11 10:26:14.949:    DHCP transaction id: 15EC

*Jan 11 10:26:14.949:    Lease: 0 secs,  Renewal: 0 secs,  Rebind: 0 secs

*Jan 11 10:26:14.949:    Next timer fires after: 00:00:04

*Jan 11 10:26:14.949:    Retry count: 2   Client-ID: cisco-000b.5f53.0740-Fa0/0

*Jan 11 10:26:14.949:    Client-ID hex dump: 636973636F2D303030622E356635332E

*Jan 11 10:26:14.953:                        303734302D4661302F30

*Jan 11 10:26:14.953:    Hostname: WadeRouterOne

*Jan 11 10:26:14.953: DHCP: SDiscover: sending 302 byte length DHCP packet

*Jan 11 10:26:14.953: DHCP: SDiscover 302 bytes

*Jan 11 10:26:14.953: IP: s=0.0.0.0 (local), d=255.255.255.255 (FastEthernet0/0), len 604, sending broad/multicast

*Jan 11 10:26:14.953:     UDP src=68, dst=67

*Jan 11 10:26:14.957:             B'cast on FastEthernet0/0 interface from 0.0.0.0

*Jan 11 10:26:18.957: DHCP: SDiscover attempt # 3 for entry:

*Jan 11 10:26:18.957: Temp IP addr: 0.0.0.0  for peer on Interface: FastEthernet0/0

*Jan 11 10:26:18.957: Temp  sub net mask: 0.0.0.0

*Jan 11 10:26:18.957:    DHCP Lease server: 0.0.0.0, state: 1 Selecting

*Jan 11 10:26:18.957:    DHCP transaction id: 15EC

*Jan 11 10:26:18.957:    Lease: 0 secs,  Renewal: 0 secs,  Rebind: 0 secs

*Jan 11 10:26:18.957:    Next timer fires after: 00:00:04

*Jan 11 10:26:18.957:    Retry count: 3   Client-ID: cisco-000b.5f53.0740-Fa0/0

*Jan 11 10:26:18.957:    Client-ID hex dump: 636973636F2D303030622E356635332E

*Jan 11 10:26:18.961:                        303734302D4661302F30

DHCP Issue with ISP on Cisco 2621XM

Hello Lewis,

Is that the entire output you get? Nothing else.

I mean based on this we can tell you that the router is sending the DHCP Discovery Packet and there is no DHCP Offer Packet with the IP address provided.

As Ashish said:

Reload the Modem so we can clear the different tables maintained on their site regarding our client and then shut no shut the Interface of the router to see what's going on (Please leave the debugs on while you try this process).

Looking for some Networking Assistance? 
Contact me directly at jcarvaja@laguiadelnetworking.com

I will fix your problem ASAP.

Cheers,

Julio Carvajal Segura
http://laguiadelnetworking.com

Looking for some Networking Assistance? Contact me directly at jcarvaja@laguiadelnetworking.com I will fix your problem ASAP. Cheers, Julio Carvajal Segura http://laguiadelnetworking.com
New Member

DHCP Issue with ISP on Cisco 2621XM

   Thank you for your reply, there is no "modem" with my connection.  It comes from the pole to the ONT on the side of the house and into the house via Cat5e.  I've reset the ONT with the same debug result.

Bronze

Re: DHCP Issue with ISP on Cisco 2621XM

Looks to me like a duplex mismatch between cisco and ont.
Try with fixed speed (100) and duplex (probably half)

Sent from Cisco Technical Support iPad App

New Member

Re: DHCP Issue with ISP on Cisco 2621XM

Thank you for your reply -- I set it to 10 and 100 (speed) with no change... I also then set half duplex and full, with no change in DHCP logs.

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