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switch port "shutdown" and "no shutdown"- what exactly happens?

 

 

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m4rtntns at gmail

Jun 2, 2011, 4:07 AM

Post #1 of 5 (2695 views)
Permalink
switch port "shutdown" and "no shutdown"- what exactly happens?

Hi,
rather stupid subject, but the thing is, that I have one Cisco
WS-C2950-24 switch, which has one Motorola radio device connected to
one of fast-ethernet ports:

WS-C2950-24[Fa0/1] <-> [eth]Motorola_radio_device

Problem is, that about once every 24h this connection stops forwarding
traffic. I have changed the fast-ethernet ports in WS-C2950-24 switch
and even replaced the switch with a new one, I have replaced the
Motorola_radio_device, there are no interface flaps and errors on
switch port, nothing interesting in the Motorola_radio_device log
file. Both devices are behind the proper UPS. Once the traffic between
those two devices stops, simple "shutdown" and "no shutdown" to the
switch port helps. Cat5e cable between the devices is 75m(246 feet)
long. One might suspect the cable/connectors, but on the other hand
there really are no errors on the switch port. What might cause the
issue where reinitialization of the Ethernet port reallows traffic
forwarding? Might there be a possibility to reproduce such situation
in the lab?

regards,
martin
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andrew.koch at gawul

Jun 2, 2011, 6:49 AM

Post #2 of 5 (2619 views)
Permalink
Re: switch port "shutdown" and "no shutdown"- what exactly happens? [In reply to]

On Thu, Jun 2, 2011 at 06:07, Martin T <m4rtntns [at] gmail> wrote:
> Hi,
> rather stupid subject, but the thing is, that I have one Cisco
> WS-C2950-24 switch, which has one Motorola radio device connected to
> one of fast-ethernet ports:
>
> WS-C2950-24[Fa0/1] <-> [eth]Motorola_radio_device
>
> Problem is, that about once every 24h this connection stops forwarding
> traffic. I have changed the fast-ethernet ports in WS-C2950-24 switch
> and even replaced the switch with a new one, I have replaced the
> Motorola_radio_device, there are no interface flaps and errors on
> switch port, nothing interesting in the Motorola_radio_device log
> file. Both devices are behind the proper UPS. Once the traffic between
> those two devices stops, simple "shutdown" and "no shutdown" to the
> switch port helps. Cat5e cable between the devices is 75m(246 feet)
> long. One might suspect the cable/connectors, but on the other hand
> there really are no errors on the switch port. What might cause the
> issue where reinitialization of the Ethernet port reallows traffic
> forwarding? Might there be a possibility to reproduce such situation
> in the lab?

Hi Martin,

You mention this Motorola device is a radio. Is this a receiver only,
or a transmitter also? Is it putting out a signal of considerable
strength? I have seen all sorts of odd troubles when RFI gets induced
into a device that is not intended of receiving it, including
completely seizing up. Assuming this is a transceiver, I wonder if
you have proper grounding of the radio so that it puts its RF to
ground rather than to that nice cable you strung for your ethernet
connectivity. Also, have you isolated the radio from the switch -
used fiber or an isolator block?

This only happens on the 24th? Is the radio setup to do something on
that day, such as a pre-scheduled test?

Being that the cable is 75m, it may also be acting as an antenna.
Again, changing this to a fiber connection would eliminate this
potential pickup of noise. Using a properly terminated shielded cable
may also be a choice. If neither of these are feasible, you could run
the ethernet cabling through a ferrite core at each end that would
prevent some noise from entering the switch and radio.

As far as the specifics in the switch during a shut/no shut, I am not
certain. However, if the radio is inducing bits to flip in registers
or overloading the ethernet port receiver, resetting the port may
refire the receiver correctly.

HTH,
Andy Koch
KC9GXN
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ppauly at gmail

Jun 2, 2011, 7:05 AM

Post #3 of 5 (2615 views)
Permalink
Re: switch port "shutdown" and "no shutdown"- what exactly happens? [In reply to]

You can also try something like this:

http://parts.digikey.com/1/parts/672213-ferrite-cylinder-clamp-black-28a0640-0a2.html

and put it on your ethernet cable. Even better would be to loop it
through a couple times instead of just once.



On Thu, Jun 2, 2011 at 9:49 AM, Andrew Koch <andrew.koch [at] gawul> wrote:
> On Thu, Jun 2, 2011 at 06:07, Martin T <m4rtntns [at] gmail> wrote:
>> Hi,
>> rather stupid subject, but the thing is, that I have one Cisco
>> WS-C2950-24 switch, which has one Motorola radio device connected to
>> one of fast-ethernet ports:
>>
>> WS-C2950-24[Fa0/1] <-> [eth]Motorola_radio_device
>>
>> Problem is, that about once every 24h this connection stops forwarding
>> traffic. I have changed the fast-ethernet ports in WS-C2950-24 switch
>> and even replaced the switch with a new one, I have replaced the
>> Motorola_radio_device, there are no interface flaps and errors on
>> switch port, nothing interesting in the Motorola_radio_device log
>> file. Both devices are behind the proper UPS. Once the traffic between
>> those two devices stops, simple "shutdown" and "no shutdown" to the
>> switch port helps. Cat5e cable between the devices is 75m(246 feet)
>> long. One might suspect the cable/connectors, but on the other hand
>> there really are no errors on the switch port. What might cause the
>> issue where reinitialization of the Ethernet port reallows traffic
>> forwarding? Might there be a possibility to reproduce such situation
>> in the lab?
>
> Hi Martin,
>
> You mention this Motorola device is a radio.  Is this a receiver only,
> or a transmitter also?  Is it putting out a signal of considerable
> strength?  I have seen all sorts of odd troubles when RFI gets induced
> into a device that is not intended of receiving it, including
> completely seizing up.  Assuming this is a transceiver, I wonder if
> you have proper grounding of the radio so that it puts its RF to
> ground rather than to that nice cable you strung for your ethernet
> connectivity.  Also, have you isolated the radio from the switch -
> used fiber or an isolator block?
>
> This only happens on the 24th?  Is the radio setup to do something on
> that day, such as a pre-scheduled test?
>
> Being that the cable is 75m, it may also be acting as an antenna.
> Again, changing this to a fiber connection would eliminate this
> potential pickup of noise.  Using a properly terminated shielded cable
> may also be a choice.  If neither of these are feasible, you could run
> the ethernet cabling through a ferrite core at each end that would
> prevent some noise from entering the switch and radio.
>
> As far as the specifics in the switch during a shut/no shut, I am not
> certain.  However, if the radio is inducing bits to flip in registers
> or overloading the ethernet port receiver, resetting the port may
> refire the receiver correctly.
>
> HTH,
> Andy Koch
> KC9GXN
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp [at] puck
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>

_______________________________________________
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jkrejci at usinternet

Jun 2, 2011, 7:22 AM

Post #4 of 5 (2629 views)
Permalink
Re: switch port "shutdown" and "no shutdown"- what exactly happens? [In reply to]

Also check for stp related port blockings. Perhaps there is some sort of loop or other weird issue the switch sees. Do a "show int status" and "show span int f0/1" for port blocking status.

Sent via BlackBerry from T-Mobile

-----Original Message-----
From: Peter Pauly <ppauly [at] gmail>
Sender: cisco-nsp-bounces [at] puck
Date: Thu, 2 Jun 2011 10:05:11
To: Martin T<m4rtntns [at] gmail>
Cc: Cisco NSPs<cisco-nsp [at] puck>
Subject: Re: [c-nsp] switch port "shutdown" and "no shutdown"- what exactly happens?

You can also try something like this:

http://parts.digikey.com/1/parts/672213-ferrite-cylinder-clamp-black-28a0640-0a2.html

and put it on your ethernet cable. Even better would be to loop it
through a couple times instead of just once.



On Thu, Jun 2, 2011 at 9:49 AM, Andrew Koch <andrew.koch [at] gawul> wrote:
> On Thu, Jun 2, 2011 at 06:07, Martin T <m4rtntns [at] gmail> wrote:
>> Hi,
>> rather stupid subject, but the thing is, that I have one Cisco
>> WS-C2950-24 switch, which has one Motorola radio device connected to
>> one of fast-ethernet ports:
>>
>> WS-C2950-24[Fa0/1] <-> [eth]Motorola_radio_device
>>
>> Problem is, that about once every 24h this connection stops forwarding
>> traffic. I have changed the fast-ethernet ports in WS-C2950-24 switch
>> and even replaced the switch with a new one, I have replaced the
>> Motorola_radio_device, there are no interface flaps and errors on
>> switch port, nothing interesting in the Motorola_radio_device log
>> file. Both devices are behind the proper UPS. Once the traffic between
>> those two devices stops, simple "shutdown" and "no shutdown" to the
>> switch port helps. Cat5e cable between the devices is 75m(246 feet)
>> long. One might suspect the cable/connectors, but on the other hand
>> there really are no errors on the switch port. What might cause the
>> issue where reinitialization of the Ethernet port reallows traffic
>> forwarding? Might there be a possibility to reproduce such situation
>> in the lab?
>
> Hi Martin,
>
> You mention this Motorola device is a radio.  Is this a receiver only,
> or a transmitter also?  Is it putting out a signal of considerable
> strength?  I have seen all sorts of odd troubles when RFI gets induced
> into a device that is not intended of receiving it, including
> completely seizing up.  Assuming this is a transceiver, I wonder if
> you have proper grounding of the radio so that it puts its RF to
> ground rather than to that nice cable you strung for your ethernet
> connectivity.  Also, have you isolated the radio from the switch -
> used fiber or an isolator block?
>
> This only happens on the 24th?  Is the radio setup to do something on
> that day, such as a pre-scheduled test?
>
> Being that the cable is 75m, it may also be acting as an antenna.
> Again, changing this to a fiber connection would eliminate this
> potential pickup of noise.  Using a properly terminated shielded cable
> may also be a choice.  If neither of these are feasible, you could run
> the ethernet cabling through a ferrite core at each end that would
> prevent some noise from entering the switch and radio.
>
> As far as the specifics in the switch during a shut/no shut, I am not
> certain.  However, if the radio is inducing bits to flip in registers
> or overloading the ethernet port receiver, resetting the port may
> refire the receiver correctly.
>
> HTH,
> Andy Koch
> KC9GXN
>_______________________________________________
> cisco-nsp mailing list  cisco-nsp [at] puck
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>

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archive at http://puck.nether.net/pipermail/cisco-nsp/

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ryan at deadfrog

Jun 2, 2011, 7:35 AM

Post #5 of 5 (2656 views)
Permalink
Re: switch port "shutdown" and "no shutdown"- what exactly happens? [In reply to]

On Jun 2, 2011, at 6:07 AM, Martin T wrote:

> Hi,
> rather stupid subject, but the thing is, that I have one Cisco
> WS-C2950-24 switch, which has one Motorola radio device connected to
> one of fast-ethernet ports:
>
> WS-C2950-24[Fa0/1] <-> [eth]Motorola_radio_device
>
> Problem is, that about once every 24h this connection stops forwarding
> traffic. I have changed the fast-ethernet ports in WS-C2950-24 switch
> and even replaced the switch with a new one, I have replaced the
> Motorola_radio_device, there are no interface flaps and errors on
> switch port, nothing interesting in the Motorola_radio_device log
> file. Both devices are behind the proper UPS. Once the traffic between
> those two devices stops, simple "shutdown" and "no shutdown" to the
> switch port helps. Cat5e cable between the devices is 75m(246 feet)
> long. One might suspect the cable/connectors, but on the other hand
> there really are no errors on the switch port. What might cause the
> issue where reinitialization of the Ethernet port reallows traffic
> forwarding? Might there be a possibility to reproduce such situation
> in the lab?

Have you noticed if the port goes into a "err-disable" state?
Also, have you checked spanning-tree to see if it's blocking the port for some reason?
What radio are you running? I've got a couple pairs of Motorola PTP 800 radios and a couple pairs of BridgeWave FlexPort 80 radios on my switches (3560G) with no real issues. Some of the radios have a feature built in where they'll momentarily drop the Ethernet link if there is a perceived problem with the radio link, although you'd think it'd log if it did this. I'm just wondering if the port detects a loop and shuts down.
As others have suggested, you may have RF leaking back into your switch. RFI can cause all sorts of strange problems. Are there other transmitters near by yours that may possibly be causing problems?

Regards,
Ryan Wilkins


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