topic Re: Interface not accepting DHCP address in Routing and SD-WAN

Interface not accepting DHCP address

Adam_S — Thu, 27 Jul 2023 07:10:57 GMT

Have configured an interface on cisco 2811 for DHCP, it is up/up but not accepting an address. I've attached a basic config and DHCP debug. Any advice would be appreciated, any further info can be provided.

Re: Interface not accepting DHCP address

Peter Paluch — Thu, 27 Jul 2023 08:02:38 GMT

Adam,

There don't seem to be any attachments included with your post. I wonder if they might be getting scrubbed or something. Could you try attaching them again?

Best regards,
Peter

Re: Interface not accepting DHCP address

Adam_S — Mon, 07 Aug 2023 05:50:04 GMT

ive reattached the file. Hopefully it takes. Below are the contents just in case:

Cisco-2811#show ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES DHCP up up
FastEthernet0/1 192.168.1.2 YES NVRAM up up
FastEthernet0/1/0 unassigned YES unset up down
FastEthernet0/1/1 unassigned YES unset up down
FastEthernet0/1/2 unassigned YES unset up down
FastEthernet0/1/3 unassigned YES unset up down
FastEthernet0/1/4 unassigned YES unset up down
FastEthernet0/1/5 unassigned YES unset up down
FastEthernet0/1/6 unassigned YES unset up down
FastEthernet0/1/7 unassigned YES unset up down
FastEthernet0/1/8 unassigned YES unset up down
Serial0/3/0 unassigned YES NVRAM administratively down down
Vlan1 unassigned YES NVRAM administratively down down
Vlan25 192.168.25.1 YES NVRAM up down
NVI0 2.2.2.2 YES unset up up
Loopback0 2.2.2.2 YES NVRAM up up
Cisco-2811#show run int
Cisco-2811#show run interface fa
Cisco-2811#show run interface fastEthernet 0/0
Building configuration...

Current configuration : 204 bytes
!
interface FastEthernet0/0
description internet
ip address dhcp
ip broadcast-address 0.0.0.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip virtual-reassembly
duplex auto
speed auto
end

Cisco-2811#show version
Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 12.4(15)T9, RELEASE SOFTWARE (fc5)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Tue 28-Apr-09 13:09 by prod_rel_team

ROM: System Bootstrap, Version 12.4(13r)T5, RELEASE SOFTWARE (fc1)

Cisco-2811 uptime is 57 minutes
System returned to ROM by power-on
System image file is "flash:c2800nm-advipservicesk9-mz.124-15.T9.bin"


*Nov 26 05:32:14 AEDST: DHCP: QScan: Purging entry
*Nov 26 05:32:14 AEDST: DHCP: deleting entry 49241A08 0.0.0.0 from list
*Nov 26 05:32:14 AEDST: Temp IP addr: 0.0.0.0 for peer on Interface: FastEthernet0/0
*Nov 26 05:32:14 AEDST: Temp sub net mask: 0.0.0.0
*Nov 26 05:32:14 AEDST: DHCP Lease server: 0.0.0.0, state: 11 Purging
*Nov 26 05:32:14 AEDST: DHCP transaction id: EB4
*Nov 26 05:32:14 AEDST: Lease: 0 secs, Renewal: 0 secs, Rebind: 0 secs
*Nov 26 05:32:14 AEDST: No timer running
*Nov 26 05:32:14 AEDST: Retry count: 0 Client-ID: cisco-0015.633b.8ba0-Fa0/0
*Nov 26 05:32:14 AEDST: Client-ID hex dump: 636973636F2D303031352E363333622E
*Nov 26 05:32:14 AEDST: 386261302D4661302F30
*Nov 26 05:32:14 AEDST: Hostname: Cisco-2811
*Nov 26 05:32:44 AEDST: DHCP: Try 49 to acquire address for FastEthernet0/0
*Nov 26 05:32:44 AEDST: DHCP: allocate request
*Nov 26 05:32:44 AEDST: DHCP: new entry. add to queue, interface FastEthernet0/0
*Nov 26 05:32:44 AEDST: DHCP: SDiscover attempt # 1 for entry:
*Nov 26 05:32:44 AEDST: Temp IP addr: 0.0.0.0 for peer on Interface: FastEthernet0/0
*Nov 26 05:32:44 AEDST: Temp sub net mask: 0.0.0.0
*Nov 26 05:32:44 AEDST: DHCP Lease server: 0.0.0.0, state: 3 Selecting
*Nov 26 05:32:44 AEDST: DHCP transaction id: EB5
*Nov 26 05:32:44 AEDST: Lease: 0 secs, Renewal: 0 secs, Rebind: 0 secs
*Nov 26 05:32:44 AEDST: Next timer fires after: 00:00:04
*Nov 26 05:32:44 AEDST: Retry count: 1 Client-ID: cisco-0015.633b.8ba0-Fa0/0
*Nov 26 05:32:44 AEDST: Client-ID hex dump: 636973636F2D303031352E363333622E
*Nov 26 05:32:44 AEDST: 386261302D4661302F30
*Nov 26 05:32:44 AEDST: Hostname: Cisco-2811
*Nov 26 05:32:44 AEDST: DHCP: SDiscover: sending 299 byte length DHCP packet
*Nov 26 05:32:44 AEDST: DHCP: SDiscover 299 bytes
*Nov 26 05:32:44 AEDST: B'cast on FastEthernet0/0 interface from 0.0.0.0
*Nov 26 05:32:47 AEDST: DHCP: SDiscover attempt # 2 for entry:
*Nov 26 05:32:47 AEDST: Temp IP addr: 0.0.0.0 for peer on Interface: FastEthernet0/0
*Nov 26 05:32:47 AEDST: Temp sub net mask: 0.0.0.0
*Nov 26 05:32:47 AEDST: DHCP Lease server: 0.0.0.0, state: 3 Selecting
*Nov 26 05:32:47 AEDST: DHCP transaction id: EB5
*Nov 26 05:32:47 AEDST: Lease: 0 secs, Renewal: 0 secs, Rebind: 0 secs
*Nov 26 05:32:47 AEDST: Next timer fires after: 00:00:04
*Nov 26 05:32:47 AEDST: Retry count: 2 Client-ID: cisco-0015.633b.8ba0-Fa0/0
*Nov 26 05:32:47 AEDST: Client-ID hex dump: 636973636F2D303031352E363333622E
*Nov 26 05:32:47 AEDST: 386261302D4661302F30
*Nov 26 05:32:47 AEDST: Hostname: Cisco-2811
*Nov 26 05:32:47 AEDST: DHCP: SDiscover: sending 299 byte length DHCP packet
*Nov 26 05:32:47 AEDST: DHCP: SDiscover 299 bytes
*Nov 26 05:32:47 AEDST: B'cast on FastEthernet0/0 interface from 0.0.0.0
*Nov 26 05:32:51 AEDST: DHCP: SDiscover attempt # 3 for entry:
*Nov 26 05:32:51 AEDST: Temp IP addr: 0.0.0.0 for peer on Interface: FastEthernet0/0
*Nov 26 05:32:51 AEDST: Temp sub net mask: 0.0.0.0
*Nov 26 05:32:51 AEDST: DHCP Lease server: 0.0.0.0, state: 3 Selecting
*Nov 26 05:32:51 AEDST: DHCP transaction id: EB5
*Nov 26 05:32:51 AEDST: Lease: 0 secs, Renewal: 0 secs, Rebind: 0 secs
*Nov 26 05:32:51 AEDST: Next timer fires after: 00:00:04
*Nov 26 05:32:51 AEDST: Retry count: 3 Client-ID: cisco-0015.633b.8ba0-Fa0/0
*Nov 26 05:32:51 AEDST: Client-ID hex dump: 636973636F2D303031352E363333622E
*Nov 26 05:32:51 AEDST: 386261302D4661302F30

Re: Interface not accepting DHCP address

Peter Paluch — Mon, 07 Aug 2023 05:53:00 GMT

Hi Adam,

Can you remove the

ip broadcast-address 0.0.0.0 from your Fa0/0

and try again? This is a configuration for very legacy devices that used the destination IP address of

0.0.0.0 as a broadcast

rather than

255.255.255.255

However, DHCP servers commonly listen to

255.255.255.255

this might be the reason. In fact, all you need on your

Fa0/0 is ip address dhcp  and no shutdown

no other manual configuration is required.

Best regards,
Peter

Re: Interface not accepting DHCP address

johnlloyd_13 — Mon, 07 Aug 2023 06:31:59 GMT

hi,

can you do this?

interface FastEthernet0/0
no ip address dhcp
no ip broadcast-address 0.0.0.0
ip address dhcp client-id FastEthernet0/0

Re: Interface not accepting DHCP address

Peter Paluch — Mon, 07 Aug 2023 06:34:13 GMT

Hey John,

Good eye on the

ip broadcast-address 0.0.0.0

A friendful comment: The

client-id Fa0/0

forces the DHCP client to identify itself by deriving its identity from the MAC address of the

Fa0/0

interface. This is required when the DHCP server is offering a stable IP to the client based on its identification. It is very safe to try this out, but if the DHCP server is not intentionally configured in advance for this identifier, then any should do, in which case the

client-id Fa0/0

is not required.

Let's see what Adam comes back with.

Best regards,
Peter

Re: Interface not accepting DHCP address

Adam_S — Mon, 07 Aug 2023 05:54:36 GMT

thanks for the suggestion. I removed the

 ip broadcast 0.0.0.0

command, but
as soon as it tries to broadcast for a DHCP address the router inmediately
adds the command back to the interface config.

##- Please type your reply above this line -#

Re: Interface not accepting DHCP address

Adam_S — Thu, 27 Jul 2023 08:39:50 GMT

Thanks. I tried this, no difference.

Re: Interface not accepting DHCP address

Peter Paluch — Mon, 07 Aug 2023 05:56:18 GMT

Adam,

This is getting very weird.

I would like to ask you to share the full output of the

show version and show running-config

I am particularly interested in seeing the value of your configuration register, and some of the old-style configuration that might for some reason be lurking around (such as

no ip classless no ip routing

etc.).

The configuration register might be important because I do recall that there was one bit in it that forced the broadcast address to be either all-zeros or all-ones.

From the debugs, it's clear you are sending out DHCP Discover but never get back an Offer from the server.

Thank you!

Best regards,
Peter

Re: Interface not accepting DHCP address

MHM Cisco World — Mon, 07 Aug 2023 06:35:07 GMT

You try what ?

The client ID must be same as what

dhcp server

use you need to contact ISP ask them the clinet ID format they use. Then config your router to send same client ID.

Re: Interface not accepting DHCP address

Peter Paluch — Thu, 27 Jul 2023 09:08:50 GMT

Hello buddy,

I touched that topic here already: https://community.cisco.com/t5/routing/interface-not-accepting-dhcp-address/m-p/4893494/highlight/true#M386912

Unless we have an evidence that this is even an ISP scenario and not a lab test, and that the ISP is expecting a specific DHCP client ID to allocate IP addresses, we cannot say that Adam "must" do anything. Let's wait for Adam to come back with more information.

Best regards,
Peter

Re: Interface not accepting DHCP address

MHM Cisco World — Thu, 27 Jul 2023 09:15:39 GMT

Thanks I just clarify point here.

Have a nice summer

MHM

Re: Interface not accepting DHCP address

Adam_S — Thu, 27 Jul 2023 09:20:50 GMT

Right you are. Sorry i probably should of mentioned that this is indded a
test lab, connected to a cisco 3845. With the DHCP pool configured. I will
provide the request config in the next couple of days.

Re: Interface not accepting DHCP address

MHM Cisco World — Mon, 07 Aug 2023 06:36:10 GMT

if it LAB then check
the interface receive the DHCP discover must be in same subnet of DHCP POOL, check the subnet and subnet MASK
also if you use excluded

255.255.255.255 or x.x.x.255

remove it.
and check again.

have a nice summer
MHM

Re: Interface not accepting DHCP address

Georg Pauwen — Mon, 07 Aug 2023 06:38:11 GMT

Hello,

as mentioned by others, you are running a very old IOS version, which requires the DHCP broadcast to go to

0.0.0.0 instead of 255.255.255.255

I somewhere recall that the global config command

no ip source-route disables ip directed broadcasts

can you try that command and check if the interface still adds

ip directed-broadcast 0.0.0.0

to the interface ?

Re: Interface not accepting DHCP address

Peter Paluch — Mon, 07 Aug 2023 06:40:57 GMT

Hi Georg,

A very humble correction: The IOS on Adam's 2811 router is admittedly old but not tragically so - it's 12.4(15)T9. Back in my days at the university and NetAcad, we'd use even older versions (12.2, 12.3, 12.4) which would already be using

255.255.255.255, not 0.0.0.0, as the default limited-broadcast address

So I am very confident that the IOS version itself isn't the problem.

As for the

no ip source-route

that would be an interesting although unexpected correlation. Source routing is about the packet's sender explicitly putting the list of transit hops (up to 9) into the packet's header. But the packet still needs to be unicast... so I'm not sure why would that command have any bearing on the limited-broadcast address. But doesn't harm to test anyway, certainly!

I keep my hopes high about the config register and/or the complete configuration having something odd there.

Best regards,
Peter

Re: Interface not accepting DHCP address

Georg Pauwen — Thu, 27 Jul 2023 12:40:42 GMT

Hello Peter,

I am probably wrong, and you likely right. I just remembered there was something about the source routing. My very first router was running an 11.x version, there were all kinds of 'weird' things going on.

Curious to see how this gets resolved...

Re: Interface not accepting DHCP address

Peter Paluch — Mon, 07 Aug 2023 06:43:47 GMT

Hi Georg,

Oh, yes, there was this

no ip classless

configured by default, and there was the

ip subnet-zero

which allowed or disallowed the use of the first subnet of a major network (for example,

10.0.0.0/24 of 10.0.0.0/8

). Weird classful times indeed! : )

Best regards,
Peter

Re: Interface not accepting DHCP address

Joseph W. Doherty — Mon, 07 Aug 2023 06:47:02 GMT

Georg, if you do recall something

weird

about source routing, please send me a follow up message.

Reason I ask, possibly I'm among the few that liked to use source routing while troubleshooting some network issues.

BTW, I know disabling source routing applied to transit traffic, don't know if it also applies to same device sourced traffic.

Re: Interface not accepting DHCP address

Adam_S — Mon, 07 Aug 2023 05:57:31 GMT

Cisco-2811#show run
Building configuration...


Current configuration : 4851 bytes
!
version 12.4
service timestamps debug datetime localtime show-timezone
service timestamps log datetime localtime show-timezone
service password-encryption
!
hostname Cisco-2811
!
boot-start-marker
boot system flash:c2800nm-advipservicesk9-mz.124-15.T9.bin
boot-end-marker
!
logging buffered 4096 informational
enable secret 5 X.X.X
!
no aaa new-model
clock timezone AEST 10
clock summer-time AEDST recurring 1 Sun Oct 2:00 1 Sun Apr 2:00
dot11 syslog
!
!
no ip cef
no ip dhcp use vrf connected
ip dhcp excluded-address 192.168.25.1 192.168.25.100
!
ip dhcp pool LAN
network 192.168.25.0 255.255.255.0
dns-server 1.1.1.1
default-router 192.168.25.1
lease 24
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!
voice-card 0
no dspfarm
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
vtp domain home
vtp mode transparent
archive
log config
hidekeys
!
!
!
!
vlan 25
name LAN
!
!
!
!
!
interface Loopback0
ip address 2.2.2.2 255.255.255.255
ip broadcast-address 0.0.0.0
h323-gateway voip interface
!
interface FastEthernet0/0
description internet
ip address dhcp client-id FastEthernet0/0
ip broadcast-address 0.0.0.0
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 192.168.1.2 255.255.255.252
ip broadcast-address 0.0.0.0
duplex full
speed auto
!
interface FastEthernet0/1/0
switchport access vlan 25
!
interface FastEthernet0/1/1
!
interface FastEthernet0/1/2
!
interface FastEthernet0/1/3
!
interface FastEthernet0/1/4
!
interface FastEthernet0/1/5
!
interface FastEthernet0/1/6
!
interface FastEthernet0/1/7
!
interface FastEthernet0/1/8
!
interface Serial0/3/0
no ip address
ip broadcast-address 0.0.0.0
encapsulation frame-relay
shutdown
clock rate 2000000
!
interface Vlan1
no ip address
ip broadcast-address 0.0.0.0
shutdown
!
interface Vlan25
description LAN
ip address 192.168.25.1 255.255.255.0
ip broadcast-address 0.0.0.0
ip nat inside
ip virtual-reassembly
!
router ospf 100
log-adjacency-changes
network 2.2.2.2 0.0.0.0 area 0
network 192.168.1.0 0.0.0.3 area 0
network 193.168.1.0 0.0.0.3 area 0
!
no ip forward-protocol nd
ip route 0.0.0.0 0.0.0.0 FastEthernet0/0
!
!
no ip http server
no ip http secure-server
ip nat source list NAT interface FastEthernet0/0 overload
!
ip access-list extended NAT
permit ip 192.168.25.0 0.0.0.255 any
!
!
!
!
!
!
tftp-server flash:/c7921/APPS-1.0.4.SBN alias APPS-1.0.4.SBN
tftp-server flash:/c7921/CP7921G-1.0.4.LOADS alias CP7921G-1.0.4.LOADS
tftp-server flash:/c7921/GUI-1.0.4.SBN alias GUI-1.0.4.SBN
tftp-server flash:/c7921/SYS-1.0.4.SBN alias SYS-1.0.4.SBN
tftp-server flash:/c7921/TNUX-1.0.4.SBN alias TNUX-1.0.4.SBN
tftp-server flash:/c7921/TNUXR-1.0.4.SBN alias TNUXR-1.0.4.SBN
tftp-server flash:/c7921/WLAN-1.0.4.SBN alias WLAN-1.0.4.SBN
tftp-server flash:/c7911new/c7911/apps11.8-3-2-27.sbn alias apps11.8-3-2-27.sbn
tftp-server flash:/c7911new/c7911/cnu11.8-3-2-27.sbn alias cnu11.8-3-2-27.sbn
tftp-server flash:/c7911new/c7911/cvm11sccp.8-3-2-27.sbn alias cvm11sccp.8-3-2-27.sbn
tftp-server flash:/c7911new/c7911/dsp11.8-3-2-27.sbn alias dsp11.8-3-2-27.sbn
tftp-server flash:/c7911new/c7911/jar11sccp.8-3-2-27.sbn alias jar11sccp.8-3-2-27.sbn
tftp-server flash:/c7911new/c7911/SCCP11.8-3-3S.loads alias SCCP11.8-3-3S.loads
tftp-server flash:/c7911new/c7911/term06.default.loads alias term06.default.loads
tftp-server flash:/c7911new/c7911/term11.default.loads alias term11.default.loads
!
control-plane
!
!
!
voice-port 0/2/0
!
voice-port 0/2/1
!
ccm-manager redundant-host 10.12.0.21
ccm-manager mgcp
no ccm-manager fax protocol cisco
ccm-manager music-on-hold bind Loopback0
ccm-manager config server 10.12.0.21
ccm-manager config
!
mgcp
mgcp call-agent 10.12.0.25 2427 service-type mgcp version 0.1
mgcp rtp unreachable timeout 1000 action notify
mgcp modem passthrough voip mode nse
mgcp package-capability rtp-package
mgcp package-capability sst-package
mgcp package-capability pre-package
no mgcp package-capability res-package
no mgcp timer receive-rtcp
mgcp sdp simple
mgcp rtp payload-type g726r16 static
mgcp behavior g729-variants static-pt
!
mgcp profile default
!
!
!
dial-peer voice 999020 pots
service mgcpapp
port 0/2/0
!
dial-peer voice 999021 pots
service mgcpapp
port 0/2/1
!
dial-peer voice 999030 pots
service mgcpapp
!
dial-peer voice 1 voip
destination-pattern 10924
session target ipv4:10.255.255.255
!
!
!
!
call-manager-fallback
max-conferences 8 gain -6
transfer-system full-consult
ip source-address 10.255.255.255 port 2000
max-ephones 5
max-dn 5
!
!
line con 0
line aux 0
line vty 0 4
exec-timeout 0 0
privilege level 15
password 7 X.X.X
login
line vty 5
exec-timeout 0 0
password 7 X.X.X
login
!
scheduler allocate 20000 1000
ntp clock-period 17180114
ntp update-calendar
ntp server 216.239.35.4
sntp broadcast client
!
end