Over the past few years, we have been recommending the use of switch stacks in all your MDF and IDF locations. This has been done to aid in simplifying switch management, but it has led to some confusion from time to time when someone is physically working in one of the network closets.
Traditionally we have been used to seeing each of the devices in the rack in our network closet labeled with an independent name and IP address. However, the use of switch stacks changes all that. Switch stacks have only one single name and IP address assigned to them. The other devices simply just have “switch member numbers”, that is all.
A switch stack operates as a team and “elects” one member of the stack to be the “master switch” for that stack. That “stack master” switch is the only switch that has an IP address and represents the name of the “stack”. The rest of the “stack members” just appear as additional units or “cards” in the stack similar to what you would see with the multiple line cards when managing a chassis-based switch.
There is only one configuration with a switch stack and that configuration is pushed across and sync’d with all stack members. Port configurations for a specific stack member are derived from that particular switch’s stack member ID number.
Should the switch that is currently the stack master fail for any reason, the remaining members will automatically elect a new member of the stack to be the new master. So, in addition to simplified management, switch stacks can provide some amount of operational redundancy as well.
Below are some quick examples of what a 4-device switch stack looks like on the management interface:
WC3-2960X-1#show switch
Switch/Stack Mac Address : c4b3.6a3d.3600
Switch# Role Mac Address Priority Version State
*1 Master c4b3.6a3d.3600 1 4 Ready
2 Member c4b3.6a3d.a000 1 4 Ready
3 Member c4b3.6a3d.6300 1 4 Ready
4 Member c4b3.6a3c.b280 1 4 Ready
Notice in this case switch 1 is the master and the stack adopts the MAC address of the master switch.
Here is a truncated version of what the switch port listing looks like. Notice the switch member number becomes the first part of the identifier in the port number:
WC3-2960X-1#sh int status
Port Name Status Vlan Duplex Speed Type
Gi1/0/1 notconnect 31 auto auto 10/100/1000BaseTX
Gi1/0/2 connected 31 a-full a-1000 10/100/1000BaseTX
Gi1/0/3 connected 31 a-full a-1000 10/100/1000BaseTX
……..
Gi1/0/46 connected 31 a-full a-1000 10/100/1000BaseTX
Gi1/0/47 notconnect 31 auto auto 10/100/1000BaseTX
Gi1/0/48 notconnect 31 auto auto 10/100/1000BaseTX
Te1/0/1 notconnect 1 full 10G Not Present
Te1/0/2 notconnect 1 full 10G Not Present
Gi2/0/1 notconnect 31 auto auto 10/100/1000BaseTX
Gi2/0/2 notconnect 31 auto auto 10/100/1000BaseTX
Gi2/0/3 notconnect 31 auto auto 10/100/1000BaseTX
…..
Gi2/0/46 notconnect 31 auto auto 10/100/1000BaseTX
Gi2/0/47 notconnect 31 auto auto 10/100/1000BaseTX
Gi2/0/48 notconnect 31 auto auto 10/100/1000BaseTX
Te2/0/1 notconnect 1 full 10G Not Present
Te2/0/2 notconnect 1 full 10G Not Present
Gi3/0/1 notconnect 32 auto auto 10/100/1000BaseTX
Gi3/0/2 notconnect 32 auto auto 10/100/1000BaseTX
Gi3/0/3 notconnect 32 auto auto 10/100/1000BaseTX
…………….
Gi3/0/46 notconnect 32 auto auto 10/100/1000BaseTX
Gi3/0/47 notconnect 32 auto auto 10/100/1000BaseTX
Gi3/0/48 notconnect 1 auto auto 10/100/1000BaseTX
Te3/0/1 TO CORE connected trunk full 10G SFP-10GBase-LRM
Te3/0/2 notconnect 1 full 10G Not Present
Gi4/0/1 notconnect 32 auto auto 10/100/1000BaseTX
Gi4/0/2 notconnect 32 auto auto 10/100/1000BaseTX
Gi4/0/3 notconnect 32 auto auto 10/100/1000BaseTX
…………….
Gi4/0/46 notconnect 32 auto auto 10/100/1000BaseTX
Gi4/0/47 notconnect 1 auto auto 10/100/1000BaseTX
Gi4/0/48 notconnect 32 auto auto 10/100/1000BaseTX
Te4/0/1 notconnect 1 full 10G Not Present
Te4/0/2 connected trunk full 10G SFP-10GBase-LRM
Po1 TO CORE connected trunk a-full 10G
Fa0 disabled routed auto auto 10/100BaseTX
WC3-2960X-1#
This is very similar to what you would see if you were running this command on chassis-based 4500 / 6500 / 6800 switch.
Hopefully this clarifies a bit how management of switch stacks work and how the use of stacks affect labeling and port identifiers when you are working in an IDF and attempting to determine what port a device is actually plugged into.
As always if you need more information please contact our support team at support@csiny.com
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