No link: 2950 to 4006 via fiber

Unanswered Question

I am replacing a D-link with fiber connection that my predecessor installed. (It's unmanaged and doesn't recognize vlans.)

Current setup is D-link>>>fiber>>>media conv>>>4006 gig port.

However, I have tried 2 different 2950's (fiber port) using the same media conv and gig port on the 4006 and I cannot get a link to come up. I could understand the possibility of one 2950 having bad ports (unlikely as that may be) but not two different switches.

Here's the config for the pertinent ports on the 4006 and the 2950:

THIS IS THE 4006 PORT:


show int fa 5/38 switchport

Name: Fa5/38

Switchport: Enabled

Administrative Mode: trunk

Operational Mode: trunk

Administrative Trunking Encapsulation: dot1q

Operational Trunking Encapsulation: dot1q

Negotiation of Trunking: On

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Administrative Native VLAN tagging: enabled

Voice VLAN: none

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 private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled

Capture VLANs Allowed: ALL

Unknown unicast blocked: disabled

Unknown multicast blocked: disabled

Appliance trust: none

Main_Switch#



THIS IS THE 2950 PORT:

show int gi0/2 switchport

Name: Gi0/2

Switchport: Enabled

Administrative Mode: trunk

Operational Mode: down

Administrative Trunking Encapsulation: dot1q

Negotiation of Trunking: Off

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Voice VLAN: none

Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk encapsulation: dot1q

Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled

Capture VLANs Allowed: ALL


I tried the "no shut" command on both ports and even tried turning off trunking. Neither of which helped.


This is a real "hair puller." Since the D-link operates over the same hardware, I would think the 2950 would, too.


Protected: false

Appliance trust: none

MOB1#quit

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Giuseppe Larosa Mon, 03/09/2009 - 06:21
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Hello Paul,

the port is down on the C2950 side


Operational Mode: down


you may need a cross-over cable or a straight cable between the port and the transceiver.


the D-link might be able to autosense the cable type and the gig uplink of the c2950 isn't.

This could explain what you see.


Hope to help

Giuseppe


Leo Laohoo Mon, 03/09/2009 - 14:40
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On the 2950, can you do a "show post", "show run int Gi0/2", "show int Gi0/2" and "show int Gi0/2 status"?

Here is the readout from those commands:

show post

Passed

Mob1#show run int gi0/1

Building configuration...


Current configuration : 36 bytes

!

interface GigabitEthernet0/1

end


Mob1#show int gi01 /1

GigabitEthernet0/1 is down, line protocol is down (notconnect)

Hardware is Gigabit Ethernet, address is 0017.5a02.aed9 (bia 0017.5a02.aed9)

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)

Auto-duplex, Auto-speed, media type is SX

input flow-control is off, output flow-control is off

ARP type: ARPA, ARP Timeout 04:00:00

Last input never, output 00:08:38, 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 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 0 multicast, 0 pause input

0 input packets with dribble condition detected

0 packets output, 0 bytes, 0 underruns

--More-- 0 output errors, 0 collisions, 2 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 PAUSE output

0 output buffer failures, 0 output buffers swapped out

Mob1#show int gi0/1 status


Port Name Status Vlan Duplex Speed Type

Gi0/1 notconnect 1 auto auto 1000BaseSX

Mob1#

viyuan700 Mon, 03/09/2009 - 16:36
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Current setup is D-link>>>fiber>>>media conv>>>4006 gig port.


Are you replacing 2950 instead of D-Link


or your current setup is

2950>>Fiber>>>4006.


Could you please tell which Optical card (SFP/GBIC etc)you are using in 2950 and 4006 or check yourself? Cards in 2950 and 4006 shd be working on same wavelength?


It is possible that there is no problem with your configurationbut the wavelength of the optical card you are using in 2950 is not matching with your media converter/4006.


Have come across few cases on this forum where we are trying to find problem with switch config but problem is with wavlength of optical card.


As an addendum to my previous message:

I took some machines off-line so I could use the same media conv, fiber d/l as the "live" system (one using the d-link). this time I plugged in the 2950 in place of the d-link. I was able to get a link light showing activity on the media converter.

I next checked the gig port on the 4006. I did a show int on that port. It showed in the "up" state. This is something I hadn't seen before.

However, I got no replies when I pinged the 2950. Now, I'm really confused. I wouldn't think a show int would result in an "up" state (whereas before it was showing "down").

I would think it would only show "up" if the other end is also "up" and transmitting data.


glen.grant Tue, 03/10/2009 - 17:53
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Is trunking set up on both sides ? Can you post a show run of both interfaces ?

From the 4006:

interface GigabitEthernet2/18

description MMGDR

switchport trunk encapsulation dot1q

switchport mode trunk

speed 1000

duplex full

no snmp trap link-status

spanning-tree portfast

end


From the 2950:

ob1#show int gi0/1 switchport

Name: Gi0/1

Switchport: Enabled

Administrative Mode: dynamic desirable

Operational Mode: down

Administrative Trunking Encapsulation: dot1q

Negotiation of Trunking: On

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Voice VLAN: none

Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk encapsulation: dot1q

Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled

Capture VLANs Allowed: ALL

Protected: false

Appliance trust: none

Giuseppe Larosa Wed, 03/11/2009 - 11:22
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Hello Paul,


>> I would think it would only show "up" if the other end is also "up" and transmitting data.


But there is the media converter in the middle and it is this the endpoint for the C4006.

For this reason you can see up on one side while the other side is down.



Hope to help

Giuseppe


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