Dhcp problem

frank2812 · ‎02-24-2015

The client have a switch core Catalyst 4500 L3 Switch Software (cat4500-IPBASEK9-M). In this switch the custumer have configured a dhcp pool for each floor as well as vlans for VoIP. But in Floor 3 the dhcp pool is only delivering 21 ip addresses from 126 ip available as you could see in the "sh ip dhcp binding" down here. You could see that the ip addreses are been leasing from the ip address 172.16.3.200 when it should be from 172.16.3.134. i hope you could help me. I attached the sh tech from switch core and log from switch 3 from floor 3

----------------------------------------------------------------------

interface Vlan50
description Vlan VoIP Piso 3
ip address 172.16.3.129 255.255.255.128
!
interface Vlan60
description Vlan VoIP Piso 4
ip address 172.16.4.129 255.255.255.128

----------------------------------------------------------

ip dhcp excluded-address 172.16.3.129 172.16.3.133
ip dhcp excluded-address 172.16.4.129 172.16.4.133

ip dhcp pool VoIP-P3
network 172.16.3.128 255.255.255.128
domain-name seguroscanarias.com.ve
dns-server 172.16.65.2 192.67.67.2
default-router 172.16.3.129
option 150 ip 172.16.65.51 172.16.65.52

ip dhcp pool VoIP-P4
network 172.16.4.128 255.255.255.128
domain-name seguroscanarias.com.ve
dns-server 172.16.65.2 192.67.67.2
default-router 172.16.4.129
option 150 ip 172.16.65.51 172.16.65.52

---------------------------------------------------------------------------------------------------------------------------------------------------------

sh ip dhcp binding

172.16.3.200 0100.1e7a.c470.83 Feb 24 2015 03:52 AM Automatic
172.16.3.221 0100.1e7a.c415.75 Feb 24 2015 11:28 AM Automatic
172.16.3.222 0100.1930.6f45.d4 Feb 24 2015 03:48 AM Automatic
172.16.3.223 0100.1e7a.c36b.3d Feb 24 2015 03:51 AM Automatic
172.16.3.225 0100.1e4a.f32a.da Feb 24 2015 04:27 AM Automatic
172.16.3.226 0100.1e7a.26ca.bd Feb 24 2015 03:51 AM Automatic
172.16.3.227 0100.1e7a.c41d.04 Feb 24 2015 03:51 AM Automatic
172.16.3.228 0100.1e7a.c40b.e9 Feb 24 2015 03:52 AM Automatic
172.16.3.229 0100.260b.d909.51 Feb 24 2015 05:20 AM Automatic
172.16.3.231 0100.1e7a.c36b.43 Feb 24 2015 03:50 AM Automatic
172.16.3.232 0100.1e4a.0be1.bd Feb 24 2015 06:38 AM Automatic
172.16.3.233 0100.1e4a.0c3f.35 Feb 24 2015 03:52 AM Automatic
172.16.3.234 0100.1e7a.c41d.40 Feb 24 2015 04:14 AM Automatic
172.16.3.235 0100.1e7a.c40d.e3 Feb 24 2015 03:51 AM Automatic
172.16.3.236 0100.1e7a.c40d.cc Feb 24 2015 07:58 AM Automatic
172.16.3.237 0100.1e7a.c41b.21 Feb 24 2015 07:58 AM Automatic
172.16.3.238 0100.1e7a.c40e.7d Feb 24 2015 03:02 AM Automatic
172.16.3.244 0100.1e7a.c2fa.6f Feb 24 2015 10:56 AM Automatic
172.16.3.245 0100.1e7a.c41b.c9 Feb 24 2015 03:51 AM Automatic
172.16.3.246 0100.1e7a.c41b.28 Feb 24 2015 10:16 AM Automatic
172.16.3.247 0100.1e7a.c40d.c0 Feb 24 2015 03:52 AM Automatic

Charles Hill · ‎02-24-2015

Is there a problem with vlan 3 not handing out ip addresses or is it just a concern that the dhcp server is not starting at 134?

I do see a couple of ip address below 200, first one being 177.

I see vlan 2 is not starting at 134 as well.

If ip addresses are not being handed out on vlan 3, i would create a monitor session on a port and look for the dhcp messages/errors.

I do see a unrelated issue in the network with a lot of speed/duplex mismatch errors on the switch. This is probably causing a lot of slowness on these ports. Switchport side and pc both need to be hard coded or both sides need to be auto.

CPU is extremely high as well.

ERROR: Total CPU Utilization is at 96% for the past 5 seconds, which is very
  high (>90%).
  This can cause the following symptoms:
    - Input queue drops
    - Slow performance
    - Slow response in Telnet or unable to Telnet to the router
    - Slow response on the console
    - Slow or no response to ping
    - Router doesn't send routing updates

frank2812 · ‎02-24-2015

yes in this case the problem is that vlan 50 (floor 3) is not handing out all ip addresses from pool dhcp. the other problem is the cpu high utilization. In the floor 3 some users are using vlan50 like you see in the show ip dhcp binding output command.

Charles Hill · ‎02-24-2015

A little confused about the cisco phones that are experiencing the duplex mismatch.

Ports that are seeing some cisco ip phones are configured as trunk ports. (G4/6)

Is SEP001E7AC3FA77 one of the devices not getting an ip address?

If so try matching the speed and duplex the same on the switchport, pc and phone. I would suspect all three devices should be set to auto.

Try

interface g4/6

switchport mode access

switchport access vlan x

switchport voice vlan 50

spanning-tree portfast

no shut

interface Mac flapping usually indicates a loop in your network.

Show spanning-tree blockedports

show spanning-tree vlan 65

This will show you what ports are forwarding and its is also where you should discover what port shouldn't be in a forwarding state which is causing the stp loop

frank2812 · ‎02-24-2015

OK tomorrow i´ll go to the client and do all the test that you said and i´ll do some debugs

debug dhcp detail
debug ip dhcp server packet

tomorrow i´ll let you know the results

Thanks