First decide whether you want to add the new switch as master of the stack or as just a member switch. Depending on that, go through this link to follow the steps:
Tips to ad d as masterhttp://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_example09186a00807811ad.shtml#stack4
The few basic configs will syunh up from the master switch.
Cheers
Sweta
Please rate the answers if it was helpul.
Document ID: 71925 |
Introduction
This document provides the procedures to create and maintain the Cisco Catalyst 3750 Switch Stacks with the Cisco StackWise feature.
Prerequisites
Requirements
There are no specific requirements for this document.
Components Used
The information in this document is based on the Cisco Catalyst 3750 Series Switches.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Conventions
Refer to the Cisco Technical Tips Conventions for more information on document conventions.
Background Information
Stacking Technologies
Cisco Catalyst switches can be stacked with two different features.
Cisco StackWise Feature
Supported Devices/Modules:
Cisco Catalyst 3750 Series Switches
Cisco EtherSwitch Service Modules
A switch stack is a set of Cisco EtherSwitch service modules or Catalyst 3750 switches connected through their Cisco StackWise ports. One of the Cisco EtherSwitch service modules or Catalyst 3750 switches controls the operation of the stack and is called the stack master. The master LED in the front panel of the 3750 switch turns green when the switch becomes master in the stack. The stack master and the other Cisco EtherSwitch service modules or Catalyst 3750 switches in the stack are stack members. The stack members use the Cisco StackWise technology to behave and work together as a unified system. Layers 2 and 3 protocols present the entire switch stack as a single entity to the network.
The stack master is the single point of stack-wide management. From the stack master, configure these:
System-level (global) features that apply to all stack members
Interface-level features for each stack member
A switch stack is identified in the network by its bridge ID and, if the switch stack operates as a Layer 3 device, its router MAC address. The MAC address of the stack master determines the bridge ID and router MAC address. Every stack member is uniquely identified by its own stack member number.
All stack members are eligible stack masters. If the stack master becomes unavailable, the stack members that remain participate in the election of a new stack master from among themselves. A set of factors determines which Cisco EtherSwitch service module or Catalyst 3750 switch is elected as the stack master.
Note: A Cisco 3750 switch can be stacked with any other model of Cisco 3750 switches. Catalyst 3750 switches that run Cisco IOS® Release 12.2(25)SEB are compatible with Cisco EtherSwitch service modules that run Cisco IOS Release 12.2(25)EZ. Catalyst 3750 switches and Cisco EtherSwitch service modules can be in the same switch stack. Within this switch stack, the Catalyst 3750 switch or the Cisco EtherSwitch service module can be the stack master.
Cisco GigaStack Feature
Supported Devices/Modules:
Cisco Catalyst 2900 XL switches
WS-X2931-XL module for Catalyst 2900 XL switches
Cisco Catalyst 2950 switches
Cisco Catalyst 3500 XL switches
Cisco Catalyst 3550 switches
The GigaStack GBIC adds port density and high-performance connectivity to supportive switches. When installed in a supportive switch, the GigaStack GBIC supports Gigabit connections in a cascaded stack or point-to-point configuration. The GigaStack GBIC automatically negotiates the duplex setting of each port to maximize the bandwidth for your configuration.
Refer to Cisco GigabitStack GBIC to install and troubleshoot Cisco GigabitStacks.
Stackwise Ports, Cables, and Connection Types
Ports
This is the rear-panel view of the Cisco Catalyst 3750-24TS, 3750G-24T, 3750G-12S, 3750G-16TD, and 3750-48TS:
| No. | Description |
|---|---|
| 1 | StackWise Ports |
| 2 | RJ-45 Console Port |
| 3 | Fan Exhaust |
| 4 | AC Power Connector |
| 5 | RPS 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.
Cables
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 Number | Description |
|---|---|
| CAB-STACK-50CM | Cisco StackWise 50-cm stacking cable |
| CAB-STACK-1M | Cisco StackWise 1-m stacking cable |
| CAB-STACK-3M | Cisco 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
Creation and Management of Cisco Catalyst 3750 Stacks
In this section, you are presented with the information needed to configure the StackWise stacks described in this document.
Note: Use the Command Lookup Tool (registered customers only) to obtain more information on the commands used in this section.
Stack Member Numbers
The stack member number (1 to 9) identifies each member in the switch stack. The member number also determines the interface-level configuration that a stack member uses. You can display the stack member number if you use the show switch user EXEC mode command.
3750-Stk>show switch Current Switch# Role Mac Address Priority State -------------------------------------------------------- 1 Slave 0016.4748.dc80 5 Ready *2 Master 0016.9d59.db00 1 Ready
The default stack member number of a 3750 switch is 1. When it joins a switch stack, its default stack member number changes to the lowest available member number in the stack. Stack members in the same switch stack cannot have the same stack member number. Every stack member, which includes a standalone switch, retains its member number until you manually change the number or unless the number is already used by another member in the stack.
How do you manually change the member number?
Go to global configuration mode.
Issue the command switch current-stack-member-number renumber new-stack-member-number .
Return to the privileged EXEC mode and reload the member with the command reload slot current-stack-member-number .
After the member boots up, issue the command show switch to verify the stack member number. If the number is used by another member in the stack, the switch selects the lowest available number in the stack.
If you move a stack member to a different switch stack, the stack member retains its number only if the number is not used by another member in the stack. If it is used by another member in the stack, the switch selects the lowest available number in the stack. The switch is able to retain the stack member number as an environment variable. You can also renumber a switch from the bootloader switch: prompt with the command set SWITCH_NUMBER stack-member-number .
If you merge switch stacks, the switches that join the switch stack of a new stack master select the the lowest available numbers in the stack.
Priority Values
A higher priority value for a stack member increases its likelihood to be elected stack master and to retain its stack member number. The priority value can be 1 to 15. The default priority value is 1. You can display the stack member priority value with the show switch user EXEC mode command.
3750-Stk>show switch Current Switch# Role Mac Address Priority State -------------------------------------------------------- 1 Slave 0016.4748.dc80 1 Ready *2 Master 0016.9d59.db00 5 Ready
Cisco recommends that you assign the highest priority value to the switch that you prefer to be the stack master. This ensures that the switch is re-elected as stack master if a re-election occurs.
How do you change the priority value?
From the global configuration mode, issue the command switch stack-member-number priority new-priority-value .
From the bootloader switch: prompt, issue the command set SWITCH_PRIORITY new-priority-value .
Even though the priority value applies immediately to the member, it will not affect the status of the current stack master. New priority value will play a role in the next stack-master election.
Stack Master Election
How is the stack master elected?
These rules have been defined to determine which unit within a stack is chosen as the master. When switches are added or stacks are merged, the master will be chosen based on these rules, in the order specified:
The switch that is currently the stack master
Note: When stacks merge, the elected stack master would have been the master of one of the merged stacks.
Note: When stacks partition, the stack master of the original stack will be the master of its partition.
The switch with the highest stack member priority value
Note: Cisco recommends that you assign the highest priority value to the switch that you prefer to be the stack master. This ensures that the switch is re-elected as stack master if a re-election occurs.
The switch that uses the non-default interface-level configuration
The switch with the higher Hardware/Software priority. These switch software versions are listed from highest to lowest priority:
Cryptographic IP services image software
Noncryptographic IP services image software
Cryptographic IP base image software
Noncryptographic IP base image software
Note: Switches that run Cryptographic or IP services image will take a longer time to load than Non-Cryptographic or IP base image. When you power on or reset an entire switch stack, some stack members will not participate in the stack master election. This is because stack members that are powered on within the same 20-second time frame participate in the stack master election and have a chance to become the stack master. Stack members that are powered on after the 20-second time frame do not participate in this initial election and only become stack members. At times, switches with lower software priority can become the stack master, but all stack members will participate in the stack master re-election.
The switch with the longest system up-time
The switch with the lowest MAC address
Note: Data forwarding will not be affected within the stack master election.
When is the stack master elected?
When the whole switch stack is reset1
When the stack master is reset or powered off
Note: If you reset the stack master, it would reset the whole stack.
When the stack master is removed from the stack
When the stack master switch has failed
The switch stack membership is increased by if you add powered-on standalone switches or switch stacks.1
1Within these events, the current stack master has a greater chance to get re-elected.
Hardware Compatibility
The Cisco Catalyst 3750 series switches use Switch Database Management (SDM) templates to optimize the system resources for specific features dependent on how the switch is used in the network. There are two versions of the SDM templates: Desktop and Aggregator. The 3750-12S switch alone supports both templates. All other model switches of the 3750 series support only the Desktop version.
When a Cisco Catalyst 3750 switch stack consists of 3750-12S and other models, make sure to use only the Desktop SDM template. This is an output from the show switch command when an SDM mismatch exists:
3750-Stk# show switch Current Switch# Role Mac Address Priority State ------------------------------------------------------------ *2 Master 000a.fdfd.0100 5 Ready 4 Member 0003.fd63.9c00 5 SDM Mismatch
To change the SDM template on a 3750-12S to Desktop version, complete these steps:
3750-Stk# conf t
3750-Stk(config)# sdm prefer routing desktop
3750-Stk(config)# exit
3750-Stk# reload
For more information on the SDM templates, refer to Configuring SDM Templates.
Software Compatibility
Software compatibility between the stack members is determined by the Stack Protocol Version number. To view the stack protocol version of your switch stack, you can issue the show platform stack-manager all command.
3750-Stk# show platform stack-manager all Current Switch# Role Mac Address Priority State -------------------------------------------------------- 1 Slave 0016.4748.dc80 5 Ready *2 Master 0016.9d59.db00 1 Ready !--- part of output elided Stack State Machine View ============================================================== Switch Master/ Mac Address Version Uptime Current Number Slave (maj.min) State --------------------------------------------------------------------- 1 Slave 0016.4748.dc80 1.11 8724 Ready 2 Master 0016.9d59.db00 1.11 8803 Ready !--- rest of output elided
Switches with the same Cisco IOS software version have the same stack protocol version. Such switches are fully compatible, and all features function properly across the switch stack. Switches with the same Cisco IOS software version as the stack master immediately join the switch stack.
If an incompatibility exists, the fully functional stack members generate a system message that describes the cause of the incompatibility on the specific stack members. The stack master sends the message to all stack members.
Switches with different Cisco IOS software versions likely have different stack protocol versions. Switches with different major version numbers are incompatible and cannot exist in the same switch stack.
3750-Stk# show switch Current Switch# Role Mac Address Priority State -------------------------------------------------------- 1 Member 0015.c6f5.6000 1 Version Mismatch *2 Master 0015.63f6.b700 15 Ready 3 Member 0015.c6c1.3000 5 Ready
Switches with the same major version number but with a different minor version number as the stack master are considered partially compatible. When connected to a switch stack, a partially compatible switch enters version-mismatch (VM) mode and cannot join the stack as a fully functional member. The software detects the mismatched software and tries to upgrade (or downgrade) the switch in VM mode with the switch stack image or with a tar file image from the switch stack flash memory. The software uses the automatic upgrade (auto-upgrade) and the automatic advise (auto-advise) features.
The auto-upgrade occurs if the software release that runs on the stack master is compatible with the switch in VM mode and the tar file of the current image is available with any of the stack members. If tar file of the current image is not available, the auto-advise feature will recommend that a compatible image be downloaded with the required commands. The auto-upgrade and auto-advise features do not work if the switch master and switch in VM mode run different feature sets/packaging levels (IP services and IP base), but, from Cisco IOS Software Release 12.2(35)SE, auto-upgrade does support upgrades between cryptographic and non-cryptographic images of the same packaging level.
Note: If the auto upgrade does not work on the switch that shows the version mismatch error, use TFTP to manually upgrade the switch.
Create a Switch Stack from Two Stand-alone Stacks
This example shows how a switch stack is created from two stand-alone stacks.
Switch-A and Switch-B are merged together to form the stack.
and
A stack-master election occurs between Switch-A and Switch-B; let us consider that Switch-B wins.
Switch-A will reload itself and join the switch stack.
The stack member number of Switch-A will change since it conflicts with Switch-B. Switch-A will choose the lowest available stack number, which in this case, is number "2".
Create a Switch Stack from Two Two-member Stacks
This example shows how two switch stacks merge to form a stack.
The first switch stack consists of two members: Switch-A and Switch-B.
The second switch stack consists of members Switch-C and Switch-D with Switch-C as the stack master.
When these two switch stacks are merged together, the election for stack master occurs; let us consider that Switch-B wins the election.
Switch-A will retain its stack member number.
Switch-C and Switch-D will reload themselves and join the stack with new stack member numbers of "3" and "4" respectively.
