cwtang
asked on
Cisco 3750 DHCP
Hi,
I have a cisco 3750 stack. I would like to setup dhcp server on the switch itself and issue ip addresses. However, I dont seems to be able to get any ip address when either phone or pc are connected to the switch. I have attached the commands for reference. Thanks
Interface vlan 1
ip address 172.24.224.2 255.255.254.0
ip helper-address 172.24.224.2
interface vlan 2
ip address 10.0.0.2 255.255.255.0
ip helper-address 10.0.0.2
ip dhcp pool data
network 172.24.224.0 255.255.254.0
default-router 172.24.224.2
dns-server 192.168.10.5
lease 3
ip dhcp pool voice
network 10.0.0.0 255.255.255.0
default-router 10.0.0.2
dns-server 192.168.10.5
lease 3
From the debug, I could see request for dhcp being received on the switch, however, I could not see any requests being acknowledge and being sent to the clients.
Can anyone advise what could be preventing the switch itself from issusing ip address? Thanks.
I have a cisco 3750 stack. I would like to setup dhcp server on the switch itself and issue ip addresses. However, I dont seems to be able to get any ip address when either phone or pc are connected to the switch. I have attached the commands for reference. Thanks
Interface vlan 1
ip address 172.24.224.2 255.255.254.0
ip helper-address 172.24.224.2
interface vlan 2
ip address 10.0.0.2 255.255.255.0
ip helper-address 10.0.0.2
ip dhcp pool data
network 172.24.224.0 255.255.254.0
default-router 172.24.224.2
dns-server 192.168.10.5
lease 3
ip dhcp pool voice
network 10.0.0.0 255.255.255.0
default-router 10.0.0.2
dns-server 192.168.10.5
lease 3
From the debug, I could see request for dhcp being received on the switch, however, I could not see any requests being acknowledge and being sent to the clients.
Can anyone advise what could be preventing the switch itself from issusing ip address? Thanks.
What IOS version are you using?
Just out of curiousity, have you tried it without the helper commands? I have not setup multiple scopes on a router/switch and forwarded the request to itself. I always forward it off net, try it with one VLAN and one DHCP pool with the helper command, which should work fine, then start adding each piece until it breaks. I am curious to know how this works for you as we may be forced to do the same with our voice and data at a remote location.
ASKER
Hi, using ios version 12.2(25. Thanks.
ASKER
Without the helper commands, it will not work. Initially i have set up a dhcp scope for voice only, as the phones are not able to pick up the ip address, I have included the data scope to perform debug. From the data, I observe that the switch is not acknowledging dhcp request, but only accepting it, thus clients are not getting ip address.
Can anyone advise what could be preventing the switch itself from issusing ip address? Thanks.
Can anyone advise what could be preventing the switch itself from issusing ip address? Thanks.
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ASKER
Hi, I have attached a config of an interface for reference. Thanks.
interface GigabitEthernet4/0/38
description *** Port to Phone/PC ***
switchport mode access
switchport voice vlan 2
mls qos trust cos
no cdp enable
spanning-tree portfast
interface GigabitEthernet4/0/38
description *** Port to Phone/PC ***
switchport mode access
switchport voice vlan 2
mls qos trust cos
no cdp enable
spanning-tree portfast
when you check the phone it sees the vlan 2 tag correct, I have always put ours in trunk mode or dynamic auto. try changing one of the ports to this. can you make sure this works with an off router DHCP so we can verify the switch is forwarding to the phone and the data portion if you haven't already done so. I am with it really does not make sense why the switch is not issuing this back to the clients...
switch trunk encap dot1q
switch mode trunk
switch trunk native vlan 1 <- I think this is understand with Vlan 1
switch voice vlan 2
mls qos trust cos
switch trunk encap dot1q
switch mode trunk
switch trunk native vlan 1 <- I think this is understand with Vlan 1
switch voice vlan 2
mls qos trust cos
ASKER
Hi, when i check the phone, surprisingly, I do not see the vlan 2 tag. The phone is just in broadcast asking for an ip address. I have changed it to trunk, it seems that still I am not able to get an ip address.
from the switch do:
show interface g4/0/38 switchport
it will give you the operational mode of the port, trunk, tags, etc...
show interface g4/0/38 switchport
it will give you the operational mode of the port, trunk, tags, etc...
ASKER
Hi,
Thanks for the help. It seems that after i rebooted the switch and reconfigure the dhcp, everything seems to work. Thanks.
Thanks for the help. It seems that after i rebooted the switch and reconfigure the dhcp, everything seems to work. Thanks.