Solved: Cisco 2950 - 3350 Trunking issue - Port not lighting up

CSCO11511067 · ‎11-12-2013

Hi There,

I have two switches I am trying to connect a 2950 and a 3350. I have a crossover cable connecting them from fa0/24 to fa0/24 setup as a trunk,

however they won't connect and the port on both switches is down, (e.g no port light coming on on switch)

here is some show commands from both switches.. does anyone know where I am going wrong.. thanks in advance

2950#sh ip int brief

Interface IP-Address OK? Method Status Protocol

Vlan1 192.168.0.11 YES NVRAM up up

FastEthernet0/1 unassigned YES unset up up

FastEthernet0/2 unassigned YES unset down down

FastEthernet0/3 unassigned YES unset down down

FastEthernet0/4 unassigned YES unset down down

.......

FastEthernet0/24 unassigned YES unset down down

2950#sh vlan

VLAN Name Status Ports

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

1 default active Fa0/2, Fa0/3, Fa0/4, Fa0/5, Fa0/6, Fa0/7, Fa0/8, Fa0/9, Fa0/10, Fa0/11, Fa0/12, Fa0/13, Fa0/14, Fa0/15, Fa0/16, Fa0/17, Fa0/18, Fa0/19, Fa0/20

Fa0/21, Fa0/22, Fa0/23, Fa0/24

1002 fddi-default act/unsup

1003 token-ring-default act/unsup

1004 fddinet-default act/unsup

1005 trnet-default act/unsup

VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2

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

1 enet 100001 1500 - - - - - 0 0

1002 fddi 101002 1500 - - - - - 0 0

1003 tr 101003 1500 - - - - - 0 0

1004 fdnet 101004 1500 - - - ieee - 0 0

1005 trnet 101005 1500 - - - ibm - 0 0

Remote SPAN VLANs

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

Primary Secondary Type Ports

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

2950#sh run

Building configuration...

Current configuration : 1278 bytes

!

version 12.1

no service pad

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

!

hostname 2950

!

enable secret 5 $1$JKXw$gcYpfOaSQRiQqcCuVF5371

!

ip subnet-zero

!

ip ssh time-out 120

ip ssh authentication-retries 3

!

spanning-tree mode pvst

no spanning-tree optimize bpdu transmission

spanning-tree extend system-id

!

interface FastEthernet0/1

!

interface FastEthernet0/2

!

interface FastEthernet0/3

switchport mode access

!

interface FastEthernet0/4

......

.....

!

interface FastEthernet0/24

switchport mode access

speed 100

duplex full

!

interface Vlan1

ip address 192.168.0.11 255.255.255.0

!

ip http server

!

line con 0

line vty 0 4

password cisco

login

line vty 5 15

login

!

end

2950#

3350#sh vlan

VLAN Name Status Ports

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

1 default active Fa0/1, Fa0/3, Fa0/4, Fa0/5, Fa0/6, Fa0/7, Fa0/8, Fa0/9, Fa0/10, Fa0/11, Fa0/12, Fa0/13, Fa0/14, Fa0/15, Fa0/16, Fa0/17, Fa0/18, Fa0/19, Fa0/20

Fa0/21, Fa0/22, Fa0/23, Fa0/24, Gi0/1, Gi0/2

1002 fddi-default active

1003 token-ring-default active

1004 fddinet-default active

1005 trnet-default active

VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2

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

1 enet 100001 1500 - - - - - 0 0

1002 fddi 101002 1500 - - - - - 0 0

1003 tr 101003 1500 - - - - - 0 0

1004 fdnet 101004 1500 - - - ieee - 0 0

1005 trnet 101005 1500 - - - ibm - 0 0

Remote SPAN VLANs

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

Primary Secondary Type Ports

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

3350#sh ip int brief

Interface IP-Address OK? Method Status Protocol

Vlan1 192.168.0.12 YES NVRAM up up

Vlan200 unassigned YES NVRAM down down

FastEthernet0/1 unassigned YES unset down down

FastEthernet0/2 unassigned YES unset up up

FastEthernet0/3 unassigned YES unset down down

.....

......

FastEthernet0/24 unassigned YES unset down down

GigabitEthernet0/1 unassigned YES unset down down

GigabitEthernet0/2 unassigned YES unset down down

3350#sh run

Building configuration...

Current configuration : 1728 bytes

!

version 12.1

no service pad

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

!

hostname 3350

!

enable secret 5 $1$ojzz$X.gjyIj/4JDGAUDXYP5ie1

!

ip subnet-zero

ip routing

!

spanning-tree mode pvst

spanning-tree extend system-id

!

interface FastEthernet0/1

no ip address

!

interface FastEthernet0/2

no ip address

!

interface FastEthernet0/3

switchport mode access

no ip address

!

......

!

interface FastEthernet0/24

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

duplex full

speed 100

!

interface GigabitEthernet0/1

no ip address

!

interface GigabitEthernet0/2

no ip address

!

interface Vlan1

ip address 192.168.0.12 255.255.255.0

!

interface Vlan200

no ip address

!

ip classless

ip http server

!

line con 0

line vty 0 4

password cisco

login

line vty 5 15

login

!

end

3350#

Leo Laohoo · ‎11-12-2013

I am using are cross over cables and that may be why it is not working....

Without TDR, it's hard to determine.

Loop the cable: Plug the cable in one port (access) and plug the other end to another port of the same switch (access). If the ports light up, you have a good cable. If the ports don't light up, then you've got a bad cable.

View solution in original post

Karthick Murugan · ‎11-12-2013

Hi Jessse,

In 2950, auto-mdix is not enabled by default. Can you try configuring auto-mdix under the interface and check the status?

Thanks & Regards,
Karthick Murugan
CCIE#39285

Thanks & Regards, Karthick Murugan CCIE#39285

CSCO11511067 · ‎11-12-2013

Hi Karthick,

I had a look under the interface however I don't appear to have any command for mdix-auto?

2950(config-if)#?

Interface configuration commands:

arp Set arp type (arpa, probe, snap) or timeout

bandwidth Set bandwidth informational parameter

carrier-delay Specify delay for interface transitions

cdp CDP interface subcommands

channel-group Etherchannel/port bundling configuration

channel-protocol Select the channel protocol (LACP, PAgP)

default Set a command to its defaults

delay Specify interface throughput delay

description Interface specific description

dot1x Interface Config Commands for 802.1x

down-when-looped Force looped interface down

duplex Configure duplex operation.

exit Exit from interface configuration mode

fair-queue Enable Fair Queuing on an Interface

help Description of the interactive help system

hold-queue Set hold queue depth

ip Interface Internet Protocol config commands

keepalive Enable keepalive

lacp LACP interface subcommands

load-interval Specify interval for load calculation for an interface

logging Configure logging for interface

mac-address Manually set interface MAC address

macro Command macro

mls mls interface commands

mvr MVR per port configuration

no Negate a command or set its defaults

pagp PAgP interface subcommands

random-detect Enable Weighted Random Early Detection (WRED) on an

Interface

rmon Configure Remote Monitoring on an interface

shutdown Shutdown the selected interface

snmp Modify SNMP interface parameters

spanning-tree Spanning Tree Subsystem

speed Configure speed operation.

storm-control storm configuration

switchport Set switching mode characteristics

timeout Define timeout values for this interface

transmit-interface Assign a transmit interface to a receive-only interface

tx-ring-limit Configure PA level transmit ring limit

udld Configure UDLD enabled or disabled and ignore global UDLD

setting

2950(config-if)#

Leo Laohoo · ‎11-12-2013

In 2950, auto-mdix is not enabled by default.

The reason why MDIX is not enabled by default on 2940/2950/2955 & 3550 is because MDIX is NOT SUPPORTED on this platform. MDIX support started appearing with the release of the 2960, 3750 and 3560 switches.

duplex full

speed 100

Remove these two lines from either switches.

Rashid Thompson · ‎11-12-2013

Jesse,

Have you tried a straight through cable? Also I would change the 2950's interface FastEthernet0/24 to switchport mode trunk.

CSCO11511067 · ‎11-12-2013

Ah yes, sorry, I noticed that when I posted, I did change this and both ends are indeed trunks.

I tried removing duplex full / speed 100 on one side and then both sides, this seemed to make no difference

Ive tried a straight through cable and multiple other cables

I'm starting to think that none of the cables I am using are cross over cables and that may be why it is not working....

I have lots of cables from isps etc for connection your modem to pc, but im starting to think and on closer inspection of the cable that these are all straight through cables. and as these are like devices it should only work with cross over so maybe thats why the ports are failing to light up ?

3350#sh run

interface FastEthernet0/24

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

!

2950#sh run

interface FastEthernet0/24

switchport mode trunk

Leo Laohoo · ‎11-12-2013

I am using are cross over cables and that may be why it is not working....

Without TDR, it's hard to determine.

Loop the cable: Plug the cable in one port (access) and plug the other end to another port of the same switch (access). If the ports light up, you have a good cable. If the ports don't light up, then you've got a bad cable.

CSCO11511067 · ‎11-12-2013

Good test, I was wondering... as I could plug my pc into the ports (which proved the ports were fine)

I just tried looping multiple cables like you said by plugging them into access ports on the same switch and none of them are lighting up...

So from this it appears none of my cables are cross over cables....

ill source one tomorrow and try again.

thanks for your help!

Leo Laohoo · ‎11-12-2013

I just tried  looping multiple cables

Make sure they are cross-over cables. MDIX is not supported so you won't get anything if you loop straight-through cables.

CSCO11511067 · ‎11-16-2013

Got hold of a cross over cable, worked fine - trunk established.

lesson learnt! - will have to check to make sure im using correct cables in future!

Leo Laohoo · ‎11-16-2013

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