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New Member

3750 Switch Stack query

                   Hi. I have a query about a 3750 switch stack that I hope someone can answer. In one of our offices we have a 3750 switch stack with 3 switches. One of the stack cables isnt plugged in correctly (its upside down thanks to my predecessor!), so the stack is operating at 16G half.

My question is - can i reset the stack cable in its correct position on the fly without affecting the network, or will I need to do this out of hours and reboot the stack after?

Hope you can help!!

Cheers

Everyone's tags (5)
1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Gold

3750 Switch Stack query

Yes.  It can be done.

Make sure you have at least ONE cable plugged in and you should be fine to correct the second cable.

12 REPLIES
Hall of Fame Super Gold

3750 Switch Stack query

Yes.  It can be done.

Make sure you have at least ONE cable plugged in and you should be fine to correct the second cable.

New Member

3750 Switch Stack query

That's great - one of the 2 cables is operating fine, so i'll give this a go. Many thanks for your help

New Member

3750 Switch Stack query

It has indeed worked - now operating at 32G full stack ring ...happy days.

Hall of Fame Super Gold

3750 Switch Stack query

Glad to see it's working. 

New Member

Re: 3750 Switch Stack query

Hi Leo,

I am confused with concept of 32 GB with Switch 3750 stack...

what does mean of 32 GB and how can we calculate it ?

--- is it stack cable speed ?

--- is it Switch RAM speed ?

Plz explain with simple example....

KS

Super Bronze

Re: 3750 Switch Stack query

Disclaimer


The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

I am confused with concept of 32 GB with Switch 3750 stack...

what does mean of 32 GB and how can we calculate it ?

--- is it stack cable speed ?

--- is it Switch RAM speed ?

Each StackWise port is 8 Gbps (duplex).  The 32 Gbps stack bandwidth is the pair counting duplex bandwidth.

(NB: StackWise+ ports are 16 Gbps [duplex]).

New Member

Re: 3750 Switch Stack query

Info for theoretical stack speed:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/troubleshooting/switch_stacks.html

StackWise cable is different from SFP. Stacking cable are located behind the switch. SFP is located infront where fiber or copper can be plugged in to.
Sent from Cisco Technical Support iPhone App

Hall of Fame Super Gold

3750 Switch Stack query

The stacking speed of the 3850 is rated at 480 Gbps.

This model is going to start replacing the 3750X.  Expect to hear something from Cisco in about 5 to 8 months time. 

Super Bronze

Re: 3750 Switch Stack query

Disclaimer


The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Yup, 3850 is dual 120 Gbps (duplex).

New Member

Re: 3750 Switch Stack query

To the OP:

How can a stacking cable be upside-down?! AFAIK, it can only be plugged one way.

Sent from Cisco Technical Support iPhone App

New Member

3750 Switch Stack query

Hello Experts,

As Joseph stated, connection of  two cisco 3750 in stacking using 2 port each switch.

and per stack port ( behind switch) speed is 8 Gb.

For example ( as i came to understand that),

Switch1 (stack1 port = 8GB, stack2 port = 8GB)

Switch2 (stack1 port= 8GB, stack2 port = 8GB)

total = 4 x 8 GB = 32 GB

                 OR

Stack 1 support 8 GB Duplex = 8+8 (16) GB

Stack 2 support 8 GB Duplex = 8+8 (16) GB

Stack1 + Stack2 = 32 GB

which one is correct concept behind 32 Gb speed ?

KS

Super Bronze

Re: 3750 Switch Stack query

Disclaimer


The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

The original Stackwise has, as I've noted, two 8 Gbp (duplex) stack ports per switch.  That's where the 32 Gbps, i.e. 8 * 2 (for duplex) = 16 Gbps * 2 (ports) 32 Gbps.

With StackwisePlus, Stackwise is described as all a switch's internal traffic is placed onto the stackring.  Additionally, the switch placing traffic onto the stackring is also the switch that removes the traffic (after it's transversed all the other switchs in the stack).  Effectively, the stackring performs much like the 6500's classic bus (also 32 Gbps [16 Gbps, duplex], BTW).  I.e. All the stack members share this bandwidth.

PS:

BTW, StackWisePlus besides doubling stack port bandwidth, uses its stackring bandwidth much, much better.  First, it only places unicast traffic on the ring that is non-local to the stack member.  Second, the destination stack member removes the traffic from the stackring.

The 3850's new Stack480 hasn't, as far as I know, yet documented how it uses its ring.

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