[c-nsp] Cisco IOS DHCP server problem

[Michael Ulitskiy]

It doesn't and I don't see why it would need it as both data and voip vlans 
are properly moved over trunk between the switch and the router via tagged 
traffic. Also, like I said before, I don't think data/voip vlan distinction 
matters in this case as I tried to put phone in plain access vlan with cdp 
disabled and that didn't help.
Anyway, the customer got out of patience and I was forced to put static ip in 
the phone. So this mystery will stay unsolved for the time being...

Thanks,
Michael 

On Wednesday, August 09, 2017 09:16:05 AM Dionisios Karopoulos wrote:
> On second look,
> 
> I don’t see your routers interface (Gi0) having a native vlan to be able to
> move untagged traffic between itself and the switch. Usually ip phones get
> dhcp from data vlan.
> 
> Try changing voice subnet to something else and give x.x.15.0/24 to data
> vlan and see if that works.
> 
> Kind Regards,
> Dennis
> 
> 
> -----Original Message-----
> From: Michael Ulitskiy [mailto:mulitskiy at acedsl.com]
> Sent: Tuesday, August 8, 2017 6:19 PM
> To: Dionisios Karopoulos <d.karopoulos at connecticore.com>
> Cc: cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] Cisco IOS DHCP server problem
> 
> Hello,
> 
> I did.  I tried to disable 'voice vlan' and put the phone in plain access
> vlan and disabled cdp. Still the same. Phone ignores DHCPOFFER.
> Any more ideas?
> Thanks,
> 
> Michael
> 
> -----Original Message-----
> From: Dionisios Karopoulos [mailto:d.karopoulos at connecticore.com]
> Sent: Tuesday, August 8, 2017 2:38 AM
> To: 'Michael Ulitskiy'
> Cc: cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] Cisco IOS DHCP server problem
> 
> Hello,
> 
> Try disabling cdp/lldp towards the ip phone and see if it helps.
> 
> Kind Regards,
> Dennis
> 
> 
> -----Original Message-----
> From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
> Michael Ulitskiy Sent: Monday, August 7, 2017 10:06 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Cisco IOS DHCP server problem
> 
> Hello,
> 
> 
> 
> I'm sorry to ask such a probably basic question, but I'm at loss.
> 
> I have a very trivial setup: router (3825, IOS 15.0(1)M10) - switch (3750,
> IOS 12.2(50)SE5) - ip phone (7962, firmware SCCP42.9-3-1SR3-1S)
> 
> For some reason the phone can't get ip address and I have no clue why. It
> looks like it discards router's DHCPOFFER.
> 
> Here's what I'm getting in debugging after phone powering up:
> 
> 
> 
> c199-41133#
> 
> Aug  7 14:35:50: DHCPD: client's VPN is .
> 
> Aug  7 14:35:50: DHCPD: DHCPDISCOVER received from client 010c.d996.9043.99
> on interface GigabitEthernet0/0.20.
> 
> Aug  7 14:35:50: DHCPD: Sending DHCPOFFER to client 010c.d996.9043.99
> (10.10.15.38).
> 
> Aug  7 14:35:50: DHCPD: broadcasting BOOTREPLY to client 0cd9.9690.4399.
> 
> c199-41133#
> 
> Aug  7 14:35:54: DHCPD: client's VPN is .
> 
> Aug  7 14:35:54: DHCPD: DHCPDISCOVER received from client 010c.d996.9043.99
> on interface GigabitEthernet0/0.20.
> 
> Aug  7 14:35:54: DHCPD: Sending DHCPOFFER to client 010c.d996.9043.99
> (10.10.15.38).
> 
> Aug  7 14:35:54: DHCPD: broadcasting BOOTREPLY to client 0cd9.9690.4399.
> 
> c199-41133#
> 
> Aug  7 14:36:02: DHCPD: client's VPN is .
> 
> Aug  7 14:36:02: DHCPD: DHCPDISCOVER received from client 010c.d996.9043.99
> on interface GigabitEthernet0/0.20.
> 
> Aug  7 14:36:02: DHCPD: Sending DHCPOFFER to client 010c.d996.9043.99
> (10.10.15.38).
> 
> Aug  7 14:36:02: DHCPD: broadcasting BOOTREPLY to client 0cd9.9690.4399.
> 
> 
> 
> The config is very basic, subnet is directly attached, no dhcp relays:
> 
> 
> 
> Router:
> 
> ip dhcp pool DHCP-VOIP
> 
>    network 10.10.15.0 255.255.255.0
> 
>    default-router 10.10.15.1
> 
>    dns-server 10.10.15.1
> 
> !
> 
> interface GigabitEthernet0/0.20
> 
> description VOIP VLAN
> 
> encapsulation dot1Q 20
> 
> ip address 10.10.15.1 255.255.255.0
> 
> no ip redirects
> 
> no ip proxy-arp
> 
> ip verify unicast source reachable-via rx 1
> 
> ip nat inside
> 
> ip virtual-reassembly
> 
> !
> 
> 
> 
> Switch:
> 
> interface FastEthernet2/0/8
> 
> description Universal computer/phone port
> 
> switchport access vlan 10
> 
> switchport mode access
> 
> switchport voice vlan 20
> 
> spanning-tree portfast
> 
> 
> 
> I did some googling, I found several people complaining about similar
> problem, but no solution.
> 
> Does anyone have any idea what might be wrong here or how to further
> troubleshoot it?
> 
> Thanks a lot,
> 
> 
> 
> Michael
> 
> 
> 
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp archive at
> http://puck.nether.net/pipermail/cisco-nsp/