Solved: DHCP issue on 1811w does not provide IP to connected Laptop

mahesh18 · ‎10-20-2012

Hi Everyone,

I am setting up 1811w router for accessing internet.

DHCP is configured on it but it is not providing IP to laptop connected on port fa6.

Here is config of router

dot11 ssid internet

vlan 98

authentication open

authentication key-management wpa

guest-mode

wpa-psk ascii 0 010907150A59111C390C

!

ip source-route

!

ip dhcp pool WIRELESS

import all

network 192.168.98.0 255.255.255.0

default-router 192.168.98.1

dns-server 4.2.2.2

lease 3

!

ip cef

no ipv6 cef

!

multilink bundle-name authenticated

!

vtp mode transparent

!

archive

log config

hidekeys

!

vlan 98

!

bridge irb

!

interface Dot11Radio0

no ip address

!

encryption vlan 98 mode ciphers tkip

!

ssid internet

!

speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0

54.0

station-role root

no cdp enable

!

interface Dot11Radio0.1

!

interface Dot11Radio0.98

encapsulation dot1Q 98

no cdp enable

bridge-group 98

bridge-group 98 subscriber-loop-control

bridge-group 98 spanning-disabled

bridge-group 98 block-unknown-source

no bridge-group 98 source-learning

no bridge-group 98 unicast-flooding

!

interface Dot11Radio1

no ip address

shutdown

speed basic-6.0 9.0 basic-12.0 18.0 basic-24.0 36.0 48.0 54.0

station-role root

!

interface FastEthernet0

ip address dhcp

ip nat outside

ip virtual-reassembly

duplex auto

speed auto

!

interface FastEthernet1

no ip address

shutdown

duplex auto

speed auto

!

interface FastEthernet2

!

interface FastEthernet3

!

interface FastEthernet4

!

interface FastEthernet5

!

interface FastEthernet6

switchport access vlan 98

!

interface FastEthernet7

!

interface FastEthernet8

!

interface FastEthernet9

!

interface Vlan1

no ip address

shutdown

!

interface Vlan98

no ip address

!

interface Async1

no ip address

encapsulation slip

!

interface BVI98

ip address 192.168.98.1 255.255.255.0

ip nat inside

ip virtual-reassembly

ip tcp adjust-mss 1452

!

ip forward-protocol nd

no ip http server

no ip http secure-server

!

control-plane

!

bridge 98 protocol ieee

bridge 98 route ip

!

line con 0

line 1

modem InOut

stopbits 1

speed 115200

flowcontrol hardware

line aux 0

line vty 0 4

login

!

end

thanks

mahesh

Richard Burts · ‎10-22-2012

Mahesh

Please try this in addition to my previous suggestion.
Interface VLAN 98
Bridge-group 98 spanning-disabled

HTH

Rick

Sent from Cisco Technical Support iPad App

HTH

Rick

View solution in original post

Richard Burts · ‎10-23-2012

Mahesh

This command disables spanning tree from running on the interface. Here is a link to a command reference which explains a bit more about it.

http://www.cisco.com/en/US/docs/ios/bridging/command/reference/br_a1.html#wp1015030

The logic that I used was this:

- the wired ports are in a vlan.

- for PCs connected to ports in the wired vlan to get addresses from DHCP there must be an IP address on the vlan or the vlan must be related to IRB and the BVI.

- you demonstrated that putting an IP address on the vlan will allow DHCP to work. But it requires that there be a separate DHCP pool. And you wanted to use the same pool for wired and wireless.

- So the wired vlan needed to relate to IRB and the BVI.

- the way to relate the vlan to IRB and the BVI is with the bridge-group command.

- But when you applied the bridge-group 98 command to the vlan then the vlan went to protocol down.,

- So I assumed that there should be some other command related to bridge-group that would allow the vlan to stay up. So I looked for other bridge-group commands.

HTH

Rick

HTH

Rick

View solution in original post

Richard Burts · ‎10-20-2012

Mahesh

It appears to me that the problem is that your DHCP pool is associated with the BVI. Interface fa6 is part of VLAN 98. But there is nothing to associate or connect VLAN 98 with the BVI.

HTH

Rick

Sent from Cisco Technical Support iPad App

HTH

Rick

Richard Burts · ‎10-20-2012

Mahesh

In re-reading my response I realize that I tried to identify the problem but did not suggest a solution. So let me suggest this
Interface VLAN 98
Bridge-group 98

Give it a try and let us know if it works.

HTH

Rick

Sent from Cisco Technical Support iPad App

HTH

Rick

mahesh18 · ‎10-20-2012

Hi Rick,

I did as you said.

but after doing this int vlan 98 status has changed from up up to up down.

still dhcp not working.

thanks

Mahesh

mahesh18 · ‎10-21-2012

Hi Rick,

One thing to add is that without int vlan 98

bridge-group 98 command wi fi laptops are able to get the IP from dhcp but wired pc does not.

thanks

mahesh

Richard Burts · ‎10-21-2012

Mahesh

I wonder if the problem has to do with the encapsulation command on the radio. Would you try it and see if this version of the command is supported

interface Dot11Radio0.98

encapsulation dot1Q 98 native

Also it might be helpful if you would post the output of show ip interface brief.

HTH

Rick

HTH

Rick

mahesh18 · ‎10-21-2012

Hi Rick & Reza,

Here is what i did

On the encapsulation command i added native it supports it.

interface Dot11Radio0.98

encapsulation dot1Q 98 native

Also i found that DHCP was working for Wirless connections with out command- bridged group 98 under vlan 98

ip int vlan 98

bridged-group 98

But DHCP was still not working for wired PCs.

So this is what i did

added new dhcp pool

ip dhcp pool vlan1

import all

network 192.168.97.0 255.255.255.0

default-router 192.168.97.1

dns-server 64.59.144.19

lease 0 0 1

interface Vlan1

description Wired connections

ip address 192.168.97.1 255.255.255.0

After adding above config DHCP is working fine for wired PCs as shows below

1811w# sh ip dhcp binding

Bindings from all pools not associated with VRF:

IP address Client-ID/ Lease expiration Type

Hardware address/

User name

192.168.97.6 01f0.bf97.de4f.48 Oct 21 2012 08:32 PM Automatic

192.168.98.2 40fc.894e.c48c Oct 24 2012 06:23 PM Automatic

192.168.98.3 a00b.bacf.37a5 Oct 24 2012 06:21 PM Automatic

1811w#

here is info as per Rick

1811w#             sh ip int brief
Interface                  IP-Address      OK? Method Status                Prot
ocol
Async1                     unassigned      YES NVRAM down                  down

BVI98                      192.168.98.1    YES NVRAM up                    up

Dot11Radio0                unassigned      YES NVRAM up                    up

Dot11Radio0.1              unassigned      YES unset up                    up

Dot11Radio0.98             unassigned      YES unset up                    up

Dot11Radio1                unassigned      YES NVRAM administratively down down

FastEthernet0              192.168.99.1    YES NVRAM up                    up

FastEthernet1              unassigned      YES NVRAM administratively down down

FastEthernet2              unassigned      YES unset up                    down

FastEthernet3              unassigned      YES unset up                    down

FastEthernet4              unassigned      YES unset up                    down

FastEthernet5              unassigned      YES unset up                    down

FastEthernet6              unassigned      YES unset up                    up

FastEthernet7              unassigned      YES unset up                    down

FastEthernet8              unassigned      YES unset up                    down

FastEthernet9              unassigned      YES unset up                    down

NVI0                       192.168.98.1    YES unset up                    up

Vlan1                      192.168.97.1    YES manual up                    up

Vlan98                     unassigned      YES NVRAM up                    down

Interfaces 2 to 9 are under vlan 1 now.

fa6 is connected to wired PC unde rvlan 1.

Need to why we have interface NVI0 even though NAT is done by some other router.??????

Also need to confirm thay vlan 98 is up down is this ok as we have no port which is in vlan 98 that is up up right now??

Many thanks

MAhesh

Reza Sharifi · ‎10-21-2012

Hi Mahesh,

Not very sure about this, but don't you have to also add port 6 to the bridge group?

something like this?

interface FastEthernet6

switchport access vlan 98

bridge-group 98

Reza

Richard Burts · ‎10-21-2012

Reza

I would think that the bridge-group would go on the layer 3 interface (interface vlan x) and not on the layer 2 interface (which is already inherently switching/bridging).

I would think that the additional information given by Mahesh sounds like the switch interfaces built into the router were in vlan 1 and not in vlan 98 as his original post suggests. If Mahesh would post the output of show interface status it might give us some insight into what is going on with vlan assignments.

HTH

Rick

HTH

Rick

mahesh18 · ‎10-21-2012

Hi Rick,

Here is info i provided in earlier post.

Seems you did not read it ----

Hi Rick & Reza,

Here is what i did

On the encapsulation command i added native it supports it.

interface Dot11Radio0.98

encapsulation dot1Q 98 native

Also i found that DHCP was working for Wirless connections with out command- bridged group 98 under vlan 98

ip int vlan 98

bridged-group 98

But DHCP was still not working for wired PCs.

So this is what i did

added new dhcp pool

ip dhcp pool vlan1

import all

network 192.168.97.0 255.255.255.0

default-router 192.168.97.1

dns-server 64.59.144.19

lease 0 0 1

interface Vlan1

description Wired connections

ip address 192.168.97.1 255.255.255.0

After adding above config DHCP is working fine for wired PCs as shows below

1811w# sh ip dhcp binding

Bindings from all pools not associated with VRF:

IP address Client-ID/ Lease expiration Type

Hardware address/

User name

192.168.97.6 01f0.bf97.de4f.48 Oct 21 2012 08:32 PM Automatic

192.168.98.2 40fc.894e.c48c Oct 24 2012 06:23 PM Automatic

192.168.98.3 a00b.bacf.37a5 Oct 24 2012 06:21 PM Automatic

1811w#

here is info as per Rick

1811w#             sh ip int brief
Interface                  IP-Address      OK? Method Status                Prot
ocol
Async1                     unassigned      YES NVRAM down                  down

BVI98                      192.168.98.1    YES NVRAM up                    up

Dot11Radio0                unassigned      YES NVRAM up                    up

Dot11Radio0.1              unassigned      YES unset up                    up

Dot11Radio0.98             unassigned      YES unset up                    up

Dot11Radio1                unassigned      YES NVRAM administratively down down

FastEthernet0              192.168.99.1    YES NVRAM up                    up

FastEthernet1              unassigned      YES NVRAM administratively down down

FastEthernet2              unassigned      YES unset up                    down

FastEthernet3              unassigned      YES unset up                    down

FastEthernet4              unassigned      YES unset up                    down

FastEthernet5              unassigned      YES unset up                    down

FastEthernet6              unassigned      YES unset up                    up

FastEthernet7              unassigned      YES unset up                    down

FastEthernet8              unassigned      YES unset up                    down

FastEthernet9              unassigned      YES unset up                    down

NVI0                       192.168.98.1    YES unset up                    up

Vlan1                      192.168.97.1    YES manual up                    up

Vlan98                     unassigned      YES NVRAM up                    down

Interfaces 2 to 9 are under vlan 1 now.

fa6 is connected to wired PC unde rvlan 1.

1811w#sh int status

Port Name Status Vlan Duplex Speed Type

Fa2 notconnect 1 auto auto 10/100BaseTX

Fa3 notconnect 1 auto auto 10/100BaseTX

Fa4 notconnect 1 auto auto 10/100BaseTX

Fa5 notconnect 1 auto auto 10/100BaseTX

Fa6 connected 1 a-full a-100 10/100BaseTX

Fa7 notconnect 1 auto auto 10/100BaseTX

Fa8 notconnect 1 auto auto 10/100BaseTX

Fa9 notconnect 1 auto auto 10/100BaseTX

Need to why we have interface NVI0 even though NAT is done by some other router.??????

Also need to confirm thay vlan 98 is up down is this ok as we have no port which is in vlan 98 that is up up right now??

Many thanks

MAhesh

Richard Burts · ‎10-21-2012

Mahesh

In fact I did read the information in your previous post. But thanks for posting it again to be sure that it was part of the conversation.

The show interface status clearly shows that all the router built in switch ports are in vlan 1. And that explains several parts of the problem.

- vlan 98 status is up/down because there are no ports active in the vlan.

- your original post showed that fa6 was assigned to vlan 98 but somewhere along the line that configuration was changed and you did not tell us about that.

- wired ports are not learning DHCP because DHCP is for the network in vlan 98 but there are no ports in vlan 98.

- your new DHCP pool is working because it is providing addresses in vlan 1 and all the router built in switch ports are in vlan 1.

Now that we have a better understanding of the issue - do you want to leave things as they are (and are working I guess) or do you want to go back to the original configuraton where fa8 was in vlan 98?

HTH

Rick

HTH

Rick

mahesh18 · ‎10-21-2012

Hi Rick,

Thanks for reply

- your original post showed that fa6 was assigned to vlan 98 but somewhere along the line that configuration was changed and you did not tell us about that.

Earlier the port fa6 was in assigned to vlan 98 and it had wired connection to PC.

Then i config new DHCP pool vlan1 and assigned all ports to vlan 1

after this PC connected to port fa6 got IP from DHCP pool vlan1.

Note Fa6 was wired conenction and it got IP from Vlan1.

Now question is if we assign fa6 back to vlan 98 will it get the IP from DHCP.

I tested and assigned port fa6 back to vlan 98 and it did not get the IP

here is info

1811w# sh ip int brief

Interface IP-Address OK? Method Status Prot

ocol

Async1 unassigned YES NVRAM down down

BVI98 192.168.98.1 YES NVRAM up up

Dot11Radio0 unassigned YES NVRAM up up

Dot11Radio0.1 unassigned YES unset up up

Dot11Radio0.98 unassigned YES unset up up

Dot11Radio1 unassigned YES NVRAM administratively down down

FastEthernet0 192.168.99.1 YES NVRAM up up

FastEthernet1 unassigned YES NVRAM administratively down down

FastEthernet2 unassigned YES unset up down

FastEthernet3 unassigned YES unset up down

FastEthernet4 unassigned YES unset up down

FastEthernet5 unassigned YES unset up down

FastEthernet6 unassigned YES unset up up

FastEthernet7 unassigned YES unset up down

FastEthernet8 unassigned YES unset up down

FastEthernet9 unassigned YES unset up down

NVI0 192.168.98.1 YES unset up up

Vlan1 192.168.97.1 YES manual up down

Vlan98 unassigned YES NVRAM up up

So my only question remains is port fa6 when assigned to vlan 98 and has wired connection should get IP from DHCP

or not?

If yes is there any reason why it is not getting IP from DHCP?

Regards

Mahesh

Richard Burts · ‎10-22-2012

Mahesh

It should be possible for hosts connected to the wired ports to get addresses from the DHCP that supplies the wireless also. This would require that the wired ports and the wireless are in the same VLAN and both participate fully in IRB. If it is not working then there is probably some issue in the configuration. Please post the current configuration so that we can try to find the issue.

HTH

Rick

[edit] it would also be helpful if you post the output of show interface status

HTH

Rick

mahesh18 · ‎10-22-2012

Hi Rick,

Good Morning !

Here is current config

1811w#sh running-config

Building configuration...

Current configuration : 3162 bytes

!

! Last configuration change at 22:37:51 MST Sun Oct 21 2012

! NVRAM config last updated at 15:15:11 MST Sun Oct 21 2012

!

version 12.4

service timestamps debug datetime msec localtime show-timezone

service timestamps log datetime msec localtime show-timezone

no service password-encryption

!

hostname 1811w

!

boot-start-marker

boot-end-marker

!

logging message-counter syslog

logging buffered 4096 informational

no logging console

!

no aaa new-model

clock timezone MST -7

clock summer-time MST recurring

!

dot11 syslog

!

dot11 ssid ACDinternet

vlan 98

authentication open

authentication key-management wpa

guest-mode

wpa-psk ascii 0 zaq12wsx

!

ip source-route

!

ip dhcp excluded-address 192.168.98.1

ip dhcp excluded-address 192.168.99.1

ip dhcp excluded-address 192.168.99.2

!

ip dhcp pool WIRELESS

import all

network 192.168.98.0 255.255.255.0

default-router 192.168.98.1

dns-server 64.59.144.19

lease 3

!

ip dhcp pool vlan1

import all

network 192.168.97.0 255.255.255.0

default-router 192.168.97.1

dns-server 64.59.144.19

lease 0 0 1

!

ip cef

no ipv6 cef

!

multilink bundle-name authenticated

!

vtp mode transparent

!