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Why would the "switchport voice vlan x" command cause this?

anowell
Level 1
Level 1

We just replaced a switch in our network that our voice-gateway was plugged into.  When we moved the voice-gateway connection over to the new switch we were unable to ping it until we removed the "switchport voice vlan" command on the switch port that was connected to the gateway.  Why would the "switchport voice vlan" command break this connection?  Saying it another way...why would removing the "switchport voice vlan" command allow the connection to work?  It was my understanding that unless a phone was plugged into a port with the "switchport voice vlan" command, the command essential did nothing.

Please note that the command was present on the old switch port but needed to be removed in the new switch port.

OLD SWITCH PORT CONFIG CONNECTED TO THE VOICE-GATEWAY

interface FastEthernet0/46
 description - Link to CL1120VG01 - 3825
 switchport access vlan 100
 switchport mode access
 switchport voice vlan 100
 srr-queue bandwidth share 10 10 60 20
 srr-queue bandwidth shape  10  0  0  0
 mls qos trust device cisco-phone
 mls qos trust cos
 auto qos voip cisco-phone
 spanning-tree portfast

NEW SWITCH PORT CONFIG CONNECTED TO THE VOICE-GATEWAY

interface GigabitEthernet1/0/46
 description - Link to CL1120VG01 - 3825
 switchport access vlan 100
 switchport mode access
 switchport voice vlan 100
 srr-queue bandwidth share 1 30 35 5
 priority-queue out
 mls qos trust device cisco-phone
 mls qos trust cos
 spanning-tree portfast
 service-policy input AUTOQOS-SRND4-CISCOPHONE-POLICY

All of the below outputs are from the NEW switch

CL1120SW17#show interface gi1/0/46 switchport
Name: Gi1/0/46
Switchport: Enabled
Administrative Mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: native
Negotiation of Trunking: Off
Access Mode VLAN: 100 (VLAN0100)
Trunking Native Mode VLAN: 1 (default)
Administrative Native VLAN tagging: enabled
Voice VLAN: 100 (VLAN0100)
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk Native VLAN tagging: enabled
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk associations: none
Administrative private-vlan trunk mappings: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL

CL1120SW17#show cdp neighbor gi1/0/46 details
-------------------------
Device ID: CL1120VG01
Entry address(es):
  IP address: 10.10.4.5
Platform: Cisco 3825,  Capabilities: Router Switch IGMP
Interface: GigabitEthernet1/0/46,  Port ID (outgoing port): GigabitEthernet0/0
Holdtime : 136 sec

Version :
Cisco IOS Software, 3800 Software (C3825-IPVOICEK9-M), Version 12.4(11)T2, RELEASE SOFTWARE (fc4)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2007 by Cisco Systems, Inc.
Compiled Mon 30-Apr-07 23:43 by prod_rel_team

advertisement version: 2
VTP Management Domain: ''
Duplex: full
Power Available TLV:

    Power request id: 0, Power management id: 0, Power available: 0, Power management level: 0
Management address(es):

CL1120SW1#show run interface vlan 100
!
interface Vlan100
 ip address 10.10.4.11 255.255.255.0

_____________________________

The below commands and outputs are from the voice-gateway.

interface GigabitEthernet0/0
 ip address 10.10.4.5 255.255.255.0
 ip pim sparse-dense-mode
 duplex auto
 speed auto
 media-type rj45

CL1120VG01#show interface gi0/0
GigabitEthernet0/0 is up, line protocol is up
  Hardware is BCM1125 Internal MAC, address is 001b.5359.0030 (bia 001b.5359.0030)
  Internet address is 10.10.4.5/24
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is RJ45
  output flow-control is XON, input flow-control is XON
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:14, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 85000 bits/sec, 50 packets/sec
     29 packets input, 14384 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 29 multicast, 0 pause input
     0 input packets with dribble condition detected
     60426 packets output, 12846821 bytes, 0 underruns
     2 output errors, 0 collisions, 1 interface resets
     0 babbles, 0 late collision, 0 deferred
     2 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

CL1120VG01#show cdp neighbor details
-------------------------
Device ID: CL1120SW17
Entry address(es):
  IP address: 10.10.4.27
Platform: cisco WS-C2960X-48LPS-L,  Capabilities: Switch IGMP
Interface: GigabitEthernet0/0,  Port ID (outgoing port): GigabitEthernet1/0/46
Holdtime : 157 sec

Version :
Cisco IOS Software, C2960X Software (C2960X-UNIVERSALK9-M), Version 15.0(2a)EX5, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2015 by Cisco Systems, Inc.
Compiled Mon 16-Feb-15 08:16 by prod_rel_team

advertisement version: 2
Protocol Hello:  OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=00000000FFFFFFFF010221FF0000000000000041D2991980FF0000
VTP Management Domain: ''
Native VLAN: 100
Duplex: full
Application: VoIP using vlan 100

2 Replies 2

Tagir Temirgaliyev
Spotlight
Spotlight

NEW SWITCH PORT CONFIG CONNECTED TO THE VOICE-GATEWAY

interface GigabitEthernet1/0/46
 description - Link to CL1120VG01 - 3825
 switchport access vlan 100
 switchport mode access
 switchport voice vlan 100

when connect to router you dont need switchport voice vlan.

you  need switchport voice vlan only when connect to CISCO IP PHONE

Thanks for the reply!

I understand that you would never need this command if connected to a router.  I'm just trying to understand why having this command on the switch port would cause the connection to break between the router and the switch.  What is it about the command that would cause the connection to fail?

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