Cisco stacking help

Answered Question
Jul 13th, 2010

guys we have currently 3 cisco 3750 swicthes in a stack the requirment is to add three more into stack.....just wondering can someone tell me do's and dont as i dont want to mess it up as its my first time.....the three new swcithes will be new.....can someone explain steps and important info to share with as i have heard that the new swicth can wipeoff the config of others....thanks heaps

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Correct Answer by Nagaraja Thanthry about 6 years 4 months ago

Hello,

Once you connect the switch to the stack, the stack master will push a copy of the configuration to all the switches. So, all of them will have identical configuration. But you can just access the master switch so you will not be able to see any other configuration. When the master goes down, the next switch that takes over as the master will continue with the current running configuration (one that it got from the master).

As soon as you provision the new switch, the master will add those ports to the configuration. Now, you might want to configure individual ports in appropriate vlans.The interface numbering format will be Switchnumber/0/portnumber (for example Gigabit 1/0/1 is for port 1 of the first switch. Similarly Gigabit 4/0/23 will be for 23rd port of the 4th switch)

interface GigabitEthernet 5/0/1

switchport access vlan

exit

As far as your last question is concerned, it is a good idea to wipe off the configuration from an old switch before attaching it to a running stack. That will ensure that the switch will not interfere with current stack operations.

Hope this helps.

Regards,

NT

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Nagaraja Thanthry Tue, 07/13/2010 - 21:45

Hello,

Here are the steps involved in adding a switch to the stack:

Add a stack member

- Provision the switch on the stack

Switch(config)# switch 2 provision WS-C3750G-12S

Switch(config)# end

- Power off the new switch.

- Through their StackWise ports, connect the new switch to a powered-on switch stack.

- Power on the new switch.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/relea...

In this case, the stack master is retained. The new switch is added to the switch stack. I would also suggest you to save a copy of the running configuration in the flash with a different name. That way, you will not lose any configuration in case something gets corrupted.

Hope this helps.

Regards,

NT

Ganesh Hariharan Tue, 07/13/2010 - 23:17
guys we have currently 3 cisco 3750 swicthes in a stack the requirment
is to add three more into stack.....just wondering can someone tell me
do's and dont as i dont want to mess it up as its my first time.....the
three new swcithes will be new.....can someone explain steps and
important info to share with as i have heard that the new swicth can
wipeoff the config of others....thanks heaps

Hi,

Just disconnect the cable going from the bottom of the lower switch to the top of the stack, use the new switch's cable to go from the bottom of sw2 to the top of sw3 and then plug the top port on switch 1 to the bottom of switch 3.Leave the first two switches powered on when adding the third switch and do not power on the 3 switch until the stack cabling is complete. Once you complete the stack, start and monitor the console on the new switch and you can then watch the stackwise negotiations and verify everything,ios version needs to be same on all switches.

Check out the below link for adding a switch on existing stack

http://www.ciscosystems.com.ro/en/US/docs/switches/lan/catalyst3750/software/release/12.1_19_ea1/configuration/guide/swstack.html

Hope to Help !!

Ganesh.H

The_guroo_2 Wed, 07/14/2010 - 02:31

Thanks now i am bit confused.....three switches are already configured infect i have just noted there are 4 in total.

1 first switch is connected to the 4th switch and 1st switch is connected to the second switch.

2nd switch is connected with third and first switch

3rd switch is connected with second and fourth switch

4th is connected with 3rd and first switch.

now we have to add three more.....u have said

Just disconnect the cable going from the bottom of the lower switch to  the top of the stack, use the new switch's cable to go from the bottom  of sw2 to the top of sw3 and then plug the top port on switch 1 to the  bottom of switch 3.Leave the first two switches powered on when adding  the third switch and do not power on the 3 switch until the stack  cabling is complete.

Now i have racked the three switches already.....i have put th esame level of IOS already and they are ready to go.....now interims of vtp domain and vlan info will it get automatically but before that i would like you to advise the steps in stacking and powering up the devices.....so keeping in mind 4 switches are connected as stated above and they are on....so do i have to shut the switch down to take the cable stacking off from first to last (4th swicth) or shd it be on.....secondly shd i power all switches up and then do the cabling.....ie stacking cable....sorry dude i am v confused......please advise..how we see which is stack master in current 4 switches??????

Thanks heaps

Nagaraja Thanthry Wed, 07/14/2010 - 06:55

Hello,

You do not need to turn-off the existing stack when you are connecting new switches. But the new switches need to be turned off when they are getting connected to an existing stack.

Step 1: Remove the connection between switch 4 and Switch 1

Step 2: Connect the removed connection from Switch 4 (stack port 2) to Switch 5 (new switch) stack port 1

Step 3: Connect a new stack cable between Switch 5 stack port 2 to Switch 6 stack port 1

Step 4: Connect a new stack cable between Switch 6 stack port 2 to Switch 7 stack port 1

Step 5: Connect a new stack cable between Switch 7 stack port 2 to Switch 1 stack port 1

Once all the connections are made and you have verified that they are all correct, turn on each of the new switches. As they come up, they will see that the stack is already present and a stack master has been selected. So, they just become part of the stack.

If you want to know the current master, you can issue "show switch" command and see the member number in front of which ther is a star. You can also check the LED's on the front panel. The MSTR LED will be on for the stack master indicating that it is the master.

Hope this helps.

Regards,

NT

The_guroo_2 Wed, 07/14/2010 - 21:27

Thanks for a very nice explaination now in stack i can see swicth one has priority 10 and secondary is

9 the other two has 1 which is default. Now do i ahve to config anything on new swicthes or they will get auto sonfig them selfs like SNMP etc.......my question is how has all that info stack master???? thanks........these swicthes are new if we have to put old one do we need to wipe off something thanks buddy you derserve 5 out of 5 shich is coming shortly :-) thanks again

Correct Answer
Nagaraja Thanthry Wed, 07/14/2010 - 21:37

Hello,

Once you connect the switch to the stack, the stack master will push a copy of the configuration to all the switches. So, all of them will have identical configuration. But you can just access the master switch so you will not be able to see any other configuration. When the master goes down, the next switch that takes over as the master will continue with the current running configuration (one that it got from the master).

As soon as you provision the new switch, the master will add those ports to the configuration. Now, you might want to configure individual ports in appropriate vlans.The interface numbering format will be Switchnumber/0/portnumber (for example Gigabit 1/0/1 is for port 1 of the first switch. Similarly Gigabit 4/0/23 will be for 23rd port of the 4th switch)

interface GigabitEthernet 5/0/1

switchport access vlan

exit

As far as your last question is concerned, it is a good idea to wipe off the configuration from an old switch before attaching it to a running stack. That will ensure that the switch will not interfere with current stack operations.

Hope this helps.

Regards,

NT

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