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New Member

Catalyst 2940- Switch drops connection when anothr is added.

Having an issue with two Cat 2940, they have fiber 100Base-TX. Added a new Cat switch (the second on the VLAN), the existing Cat switch drops the fiber connection. Any thoughts???

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1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Catalyst 2940- Switch drops connection when anothr is added.

The log gives you the answer: "NATIVE_VLAN_MISMATCH"

type "show vlan brief" from exec mode

make sure vlans exist on both switches, if not add them

check that the link between the two devices is trunking on the same native vlan

example:

switchA#show run interface fastethernet0/9

switchport mode trunk

switchport trunk native vlan 27

spanning-tree portfast trunk

SwitchB#show run interface fastethernet0/9

switchport mode trunk

switchport trunk native vlan 27

spanning-tree portfast trunk

Also, if running VTP make sure domain and password are the same and one is server and the other is client. You can also set them to transparent and update vlans manually.

6 REPLIES

Catalyst 2940- Switch drops connection when anothr is added.

Sounds like a physical problem. Check cabling, sfp, etc....

HTH, John *** Please rate all useful posts ***
New Member

Catalyst 2940- Switch drops connection when anothr is added.

Mandlenkosi,

     Sh logs listed below as requested.

sh log
Syslog logging: enabled (0 messages dropped, 0 messages rate-limited, 0 flushes, 0 overruns)
    Console logging: level debugging, 7 messages logged
    Monitor logging: level debugging, 0 messages logged
    Buffer logging: level debugging, 7 messages logged
    Exception Logging: size (4096 bytes)
    File logging: disabled
    Trap logging: level informational, 11 message lines logged
--More--                          
Log Buffer (4096 bytes):

00:00:11: %PLATFORM_CATALYST2940-3-C2940_UPLINK_SELECT: Fa0/9 is selected as uplink port
00:00:14: %SPANTREE-5-EXTENDED_SYSID: Extended SysId enabled for type vlan
000003: *Mar  1 00:00:16: %SYS-5-CONFIG_I: Configured from memory by console
000004: *Mar  1 00:00:16: %SYS-5-RESTART: System restarted --
Cisco Internetwork Operating System Software
IOS (tm) C2940 Software (C2940-I6Q4L2-M), Version 12.1(22)EA12, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2008 by cisco Systems, Inc.
Compiled Mon 07-Jul-08 23:44 by amvarma
000005: *Mar  1 00:00:16: %SNMP-5-COLDSTART: SNMP agent on host HC_NH_Construction_2940 is undergoing a cold start
000006: *Mar  1 00:00:16: %SNMP-5-COLDSTART: SNMP agent on host HC_NH_Construction_2940 is undergoing a cold start
000007: *Mar  1 00:00:17: %LINK-5-CHANGED: Interface Vlan1, changed state to administratively down
HC_NH_Construction_2940#

sh log

Syslog logging: enabled (0 messages dropped, 0 messages rate-limited, 0 flushes, 0 overruns)

    Console logging: level debugging, 2005 messages logged

    Monitor logging: level debugging, 0 messages logged

    Buffer logging: level debugging, 2005 messages logged

    Exception Logging: size (4096 bytes)

    File logging: disabled

    Trap logging: level informational, 2009 message lines logged

--More--                          

Log Buffer (4096 bytes):

E_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001980: *Oct 27 04:57:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001981: *Oct 27 04:58:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001982: *Oct 27 04:59:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001983: *Oct 27 05:00:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001984: *Oct 27 05:01:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001985: *Oct 27 05:02:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001986: *Oct 27 05:03:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

--More--                           001987: *Oct 27 05:04:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001988: *Oct 27 05:05:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001989: *Oct 27 05:06:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001990: *Oct 27 05:07:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001991: *Oct 27 05:08:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001992: *Oct 27 05:09:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001993: *Oct 27 05:10:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001994: *Oct 27 05:11:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

--More--                           001995: *Oct 27 05:12:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001996: *Oct 27 05:13:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001997: *Oct 27 05:14:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001998: *Oct 27 05:15:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

001999: *Oct 27 05:16:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).

002000: *Oct 28 15:27:18: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down

002001: *Oct 28 15:27:19: %LINK-3-UPDOWN: Interface FastEthernet0/7, changed state to down

002002: *Oct 28 15:27:51: %LINK-3-UPDOWN: Interface FastEthernet0/7, changed state to up

002003: *Oct 28 15:27:52: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up

--More--                           002004: *Oct 29 17:44:00: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down

002005: *Oct 29 17:44:02: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up

NH_Grd_HS_2940_01# sh log
Syslog logging: enabled (0 messages dropped, 0 messages rate-limited, 0 flushes, 0 overruns)
    Console logging: level debugging, 2005 messages logged
    Monitor logging: level debugging, 0 messages logged
    Buffer logging: level debugging, 2005 messages logged
    Exception Logging: size (4096 bytes)
    File logging: disabled
    Trap logging: level informational, 2009 message lines logged
--More--                          
Log Buffer (4096 bytes):
E_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001980: *Oct 27 04:57:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001981: *Oct 27 04:58:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001982: *Oct 27 04:59:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001983: *Oct 27 05:00:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001984: *Oct 27 05:01:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001985: *Oct 27 05:02:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001986: *Oct 27 05:03:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
--More--                           001987: *Oct 27 05:04:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001988: *Oct 27 05:05:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001989: *Oct 27 05:06:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001990: *Oct 27 05:07:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001991: *Oct 27 05:08:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001992: *Oct 27 05:09:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001993: *Oct 27 05:10:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001994: *Oct 27 05:11:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
--More--                           001995: *Oct 27 05:12:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001996: *Oct 27 05:13:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001997: *Oct 27 05:14:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001998: *Oct 27 05:15:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
001999: *Oct 27 05:16:27: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/9 (1), with HC_NH_Construction_Cisco2940 FastEthernet0/9 (27).
002000: *Oct 28 15:27:18: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down
002001: *Oct 28 15:27:19: %LINK-3-UPDOWN: Interface FastEthernet0/7, changed state to down
002002: *Oct 28 15:27:51: %LINK-3-UPDOWN: Interface FastEthernet0/7, changed state to up
002003: *Oct 28 15:27:52: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up
--More--                           002004: *Oct 29 17:44:00: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down
002005: *Oct 29 17:44:02: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up
NH_Grd_HS_2940_01#

Catalyst 2940- Switch drops connection when anothr is added.

Please post the "sh log"

New Member

Catalyst 2940- Switch drops connection when anothr is added.

Mandlenkosi,

     i posted the sh logs in the discussion.

New Member

Catalyst 2940- Switch drops connection when anothr is added.

The log gives you the answer: "NATIVE_VLAN_MISMATCH"

type "show vlan brief" from exec mode

make sure vlans exist on both switches, if not add them

check that the link between the two devices is trunking on the same native vlan

example:

switchA#show run interface fastethernet0/9

switchport mode trunk

switchport trunk native vlan 27

spanning-tree portfast trunk

SwitchB#show run interface fastethernet0/9

switchport mode trunk

switchport trunk native vlan 27

spanning-tree portfast trunk

Also, if running VTP make sure domain and password are the same and one is server and the other is client. You can also set them to transparent and update vlans manually.

New Member

Catalyst 2940- Switch drops connection when anothr is added.

Jszapipes,

    thanks, this solved the issue.

i did not need the "switchport trunk native vlan". But everything else was right on point.

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