Cisco 3750 Stacking cables connectivity

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Feb 14th, 2011
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Can any one tell me if we need to install any software or extra config for Stacking cables connectivity for Cisco 3750 switches ?

If we use stacking cables and connect all switches as one stack ? does it act like trunk link or etherchannels ?



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ranraju Mon, 02/14/2011 - 04:44
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No you dont have to install anything nor you have to do some extra configurations on the stack.

And as an answer to your second question:

Stackwise cables provide 32G of backplane speed between the switches when connected as full ring and 16G when connected as half ring, and forwards all data packets between the switch members in the stack.

For more information you could refer this link..

Hope this helps..



ajay kondapalli Thu, 02/24/2011 - 23:15
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Thanks,  If we make one switch as Master and 5 other switches as clients in a stack. Is it enough to configure VLANs and other interface config on master switch so that downstream client switches get the config from master switch by replication.  ( like VTP server -client process) .

Can we imagine this technology as Etherchannels where all the trunk links are aggregated to one logical channel. Like that , all switches are bundled into

one big switch which acts a logical unit. we connect all ASICS of all switches using stacking cables.

Is traffic routed by master switch ?  How is the routing table information shared between all swithces ?

Should we Gigabit ports as trunk links always  using SFPs ?  or can we use Fastethernet ports for trunking ?

Can any one share some sample configuration of  Master and Slave switches for better understanding . please..........



hobbe Fri, 02/25/2011 - 00:15
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  1. What type of 3750 are you trying to stack ?
  2. IF you do not want one special switch for some reason to be the stack master, or the different switches be master in a special order then you do not have to do anything. They will take care of it themselves.

What you need to do is 2 things

Make sure they are the same type, ie L2 or L3 (if none of them are 3750X then this is not an issue)

Make sure they have the same IOS.

And then do the most important thing of all, play around with them!. I can not stress the importance of this.

What I would do if I where you is simple!

Take two of the switches and designate them for lab use.

Make shure they have the exact same ios. (command: sh ver)

Erase the configuration on both of them  (command: wr er)

cut the power and connect the stack cables. (if 3750x then add the powerstack cables also)

start the switch you want to be designated master

wait for 5 minutes to have it all booted up.

start the second switch

Most likely they will now be stacked together and the one you have started up first will be the master.

do a sh ru and you will se how it works.

Now play around with it !  Use it to do different things and soon you will start to feel comfortable with it.

Good luck


sdheer Mon, 02/14/2011 - 04:55
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To  add to the above no software is required for stack cable connectiviity.



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Latchum Naidu Thu, 02/24/2011 - 23:33
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Hi Ajay,

You no need to have install any aditional softarew in your switches to do stacking.
The onlything you need to make sure is that all switches in stack (suppose 7) need to have same IOS.

Please see the below ports and cable connectivity types.

Stackwise Ports, Cables, and Connection Types


This is the rear-panel view of the Cisco Catalyst 3750-24TS, 3750G-24T, 3750G-12S, 3750G-16TD, and 3750-48TS:


1StackWise Ports
2RJ-45 Console Port
3Fan Exhaust
4AC Power Connector
5RPS Connector

Note: The location of Fan exhaust, AC power connector, RPS connector, and the number of Fan exhausts varies with the different models of Cisco Catalyst 3750 switches.


Use only approved cables, and connect only to similar Cisco equipment. Equipment can be damaged if connected to other unapproved Cisco cables or equipment.


Cable Part NumberDescription
CAB-STACK-50CMCisco StackWise 50-cm stacking cable
CAB-STACK-1MCisco StackWise 1-m stacking cable
CAB-STACK-3MCisco StackWise 3-m stacking cable

Connection Types

Full Bandwidth Connection

This illustration shows an example of a stack of Catalyst 3750 switches that provides full bandwidth and redundant StackWise cable connections:


When a cable fails at a single place, the stack will run with the half bandwidth connection.


In order to find the stack-ports through which the switches are connected to the stack, issue the show switch stack-ports command.

3750-Stk#show switch stack-ports

  Switch #    Port 1       Port 2
  --------    ------       ------
     1          Ok           Ok
     2          Ok           Ok
     3          Ok           Ok

Alternatively, in order to find the nearby switch on each port, issue the show switch neighbors command.

3750-Stk# show switch neighbors

  Switch #    Port 1       Port 2
  --------    ------       ------
      1         2            3
      2         1            3
      3         2            1

This illustration shows a stack of Cisco EtherSwitch service modules and Catalyst 3750 switches that provides full bandwidth and redundant connections:


Half Bandwidth Connection

This illustration shows an example of a stack of Catalyst 3750 switches with incomplete StackWise cable connections. This stack provides only half bandwidth and does not have redundant connections:


When a cable fails at a single place, the stack will be partitioned into two stacks.


3750-Stk# show switch stack-ports

  Switch #    Port 1       Port 2
  --------    ------       ------
     1          Ok          Down
     2          Ok           Ok
     3          Ok          Down

3750-Stk# show switch neighbors

  Switch #    Port 1       Port 2
  --------    ------       ------
     1          2           None
     2          1            3
     3          2           None

Hope this will help you.

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