topic Re: 2801 not issuing DHCP for my VLAN in Switching

2801 not issuing DHCP for my VLAN

nikalleyne — Wed, 06 Mar 2019 22:09:55 GMT

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

Re: 2801 not issuing DHCP for my VLAN

Giuseppe Larosa — Mon, 22 Nov 2010 20:04:35 GMT

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

Re: 2801 not issuing DHCP for my VLAN

nikalleyne — Mon, 22 Nov 2010 20:19:56 GMT

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

Re: 2801 not issuing DHCP for my VLAN

glen.grant — Mon, 22 Nov 2010 21:07:28 GMT

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.

Re: 2801 not issuing DHCP for my VLAN

nikalleyne — Mon, 22 Nov 2010 21:17:50 GMT

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.

Re: 2801 not issuing DHCP for my VLAN

glen.grant — Mon, 22 Nov 2010 21:26:35 GMT

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

Re: 2801 not issuing DHCP for my VLAN

nikalleyne — Mon, 22 Nov 2010 21:33:32 GMT

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

Re: 2801 not issuing DHCP for my VLAN

Richard Burts — Mon, 22 Nov 2010 22:01:59 GMT

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

Re: 2801 not issuing DHCP for my VLAN

cadet alain — Tue, 23 Nov 2010 09:56:17 GMT

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.

Re: 2801 not issuing DHCP for my VLAN

nikalleyne — Tue, 23 Nov 2010 15:30:19 GMT

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

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