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2801 not issuing DHCP for my VLAN

Hi Guys,

I'm testing a 2801 VoIP. I'm using the router on a stick concept to obtained previousl vlans (20 and 21) as well as I defined vlan 22 on the router. I wish to use the 4 switch ports on the router, so I configured a dhcp pool and assigned the interfaces to the vlan which the pool should server. However, I'm not getting any addresses on vlan 22. When I do a show dhcp server I have all 0s. Please see my configs below. All help appreciated

----- show dhcp server

DHCP server: ANY (255.255.255.255)
    Leases:   0
    Offers:   0      Requests: 0     Acks : 0     Naks: 0
    Declines: 0      Releases: 0     Query: 0     Bad: 0

------- Show Running-Config (Extract)

ip dhcp pool IT-VOICE
   network 192.168.22.0 255.255.255.0
   subnet prefix-length 8
   default-router 192.168.22.6
   domain-name maxxam.lab
   dns-server 192.168.2.8
   option 150 ip 192.168.22.253
!

!

interface FastEthernet0/0
description ***** CONNECTED TO LAN ******
no ip address
duplex auto
speed auto
auto qos voip trust
service-policy output AutoQoS-Policy-Trust
!
interface FastEthernet0/0.20
description **** CORP VLAN SUB INTERFACE *****
encapsulation dot1Q 20
ip address 192.168.20.253 255.255.255.0
!
interface FastEthernet0/0.21
description **** CORP-IT VLAN SUB INTERFACE *****
encapsulation dot1Q 21
ip address 192.168.21.253 255.255.255.0
!
interface FastEthernet0/0.22
description **** CORP-IT VOICE-VLAN SUB INTERFACE *****
encapsulation dot1Q 22
ip address 192.168.22.253 255.255.255.0
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet0/1/0
!
interface FastEthernet0/1/1
switchport access vlan 22
!
interface FastEthernet0/1/2
switchport access vlan 22
switchport voice vlan 22
!
interface FastEthernet0/1/3
switchport access vlan 22
switchport voice vlan 22
!
interface Vlan1
no ip address
!
interface Vlan22
no ip address
!

------ show vlan-switch

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1/0
10   VLAN0010                         active
20   VLAN0020                         active
22   VLAN0022                         active    Fa0/1/1, Fa0/1/2, Fa0/1/3
100  VLAN0100                         active
1002 fddi-default                     active
1003 token-ring-default               active
1004 fddinet-default                  active
1005 trnet-default                    active

Does anyone see what may be wrong here.

Thanks

Everyone's tags (3)
1 ACCEPTED SOLUTION

Accepted Solutions
Purple

Re: 2801 not issuing DHCP for my VLAN

Rick,

It is indeed not going to work( you have very good eyes- better than mine anyway  )

so doing a sh int f0/13 switchport will tell us exactly what the switches did with this command.

Regards.

Alain.

Don't forget to rate helpful posts.
9 REPLIES
Hall of Fame Super Silver

Re: 2801 not issuing DHCP for my VLAN

Hello Nikalleyne,

you  should move L3 configuration to SVI interfaces if you have an etherswitch module installed on the router

interface vlan 22

instead of subif fas0/0.20, see the 4 Etherswitch ports as separated from the routed ports

your current configuration could work if one etherswitch would be configured as L2 trunk port and connected to fas0/0 but this would be a waste of interfaces.

Hope to help

Giuseppe

New Member

Re: 2801 not issuing DHCP for my VLAN

giuslar

Hi Giuslar,
I did just that and now the computer gets the IP, however, the phones do not. They are just stuck in "Configuring IP via DHCP". Also using Wireshark I do not see the option 150 in the bootp traces. Any other thoughts?

!
ip dhcp pool IT-VOICE-POOL
   network 192.168.22.0 255.255.255.0
   default-router 192.168.22.6
   domain-name mydomain.lab    
   option 150 ip 192.168.22.253
!

interface FastEthernet0/0
description ***** CONNECTED TO LAN ******
no ip address
shutdown
duplex auto
speed auto
auto qos voip trust
service-policy output AutoQoS-Policy-Trust
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet0/1/0
switchport mode trunk
ip dhcp relay information trusted
!
interface FastEthernet0/1/1
switchport access vlan 22
switchport voice vlan 22
!
interface FastEthernet0/1/2
switchport access vlan 22
switchport voice vlan 22
!
interface FastEthernet0/1/3
switchport access vlan 22
switchport voice vlan 22
!
interface Vlan1
no ip address
!
interface Vlan22
ip address 192.168.22.253 255.255.255.0

Purple

Re: 2801 not issuing DHCP for my VLAN

   I think you misunderstood what Giuslar  meant .  You would have to move all your connections and routing info to  one the switchports . Create the layer3 SVI's for 20,21,22   and then trunk those vlans down to your lan switch . You would not use interface f0/0 at all , use one of the hwic switchports. You would then run your trunk from your hwic switchport to your lan switch .  It will not work  just putting vlan  22 on the switchports unless you are wiring the phones directly into those switchports .   Your default router in the dhcp pool should be .253 .

vlan database

vlan 20

vlan 21

vlan 22

Int vlan 20

ip address

Int vlan 21

ip address

Int vlan 22

ip address

Hwic switchport setup as a hardcoded trunk,  "switchport mode trunk " to the lan switch.

New Member

Re: 2801 not issuing DHCP for my VLAN

Hi Glen,

What you mentioed is exactly what I've done and it works for issuing dhcp. I configured f1/0/0 as a trunk and it learnt the other VLANS via VTP. I then use f0/1/1 to test whether my computer is getting IP addresse and it is. My other problem has to to do with the phones being stuck in Configuring IP via dhcp. So I think I have to research a bit more or go to another forum.

Thanks for the help guys, its much appreciated.

Purple

Re: 2801 not issuing DHCP for my VLAN

  If you are testing dhcp off those switchports be sure to add "spanning tree portfast"  to the ports before testing then see what happens.

New Member

Re: 2801 not issuing DHCP for my VLAN

That did not work. However, paying close attention to the Wireshark Capture should I not see the TFTP server when option 150 is advertised? I can see the router, DNS servers, etc. However, I see the Option 150 but not its value. I think I should be seeing the TFTP Server's ip addres. Am I correct?

I've used this document. http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a00800942f4.shtml

Hall of Fame Super Silver

Re: 2801 not issuing DHCP for my VLAN

I am not sure whether you have changed this or not. But when you showed part of the config you had this:

interface FastEthernet0/1/3
switchport access vlan 22
switchport voice vlan 22

I do not think that it works to have the access vlan and the voice vlan have the same vlan number.

HTH

Rick

Purple

Re: 2801 not issuing DHCP for my VLAN

Rick,

It is indeed not going to work( you have very good eyes- better than mine anyway  )

so doing a sh int f0/13 switchport will tell us exactly what the switches did with this command.

Regards.

Alain.

Don't forget to rate helpful posts.
New Member

Re: 2801 not issuing DHCP for my VLAN

Rick and Alain,

You guys, were both correct. However, I needed to change from

interface FastEthernet0/1/3
switchport access vlan 22
switchport voice vlan 22

TO

interface FastEthernet0/1/3
switchport access vlan 22


I now have dial tone, thanks for paying attention for me. The funny thing is in my Packe tracer lab I did not have switchport access vlan22 and switchport voice configured so how I ended up doing it in the production environment I really don't know.

Cheers guys

Thanks

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