Administrator Guide

Port Extender (PE) Stacking
You can stack up to eight port extenders using the mini-SAS stack ports on the back panel. The C1048P supports stacking only with other
C1048P port extenders. The N20xx series devices support stacking only with other N20xx series port extenders. The N30xx series devices
support stacking only with other N30xx series port extenders. Stacking is not supported on C9010 switches. To set up a PE stack, follow
the installation procedure in the Dell Networking C1048P Getting Started Guide, Dell Networking C1048P Installation Guide, or Dell
Networking N20xx/N30xx Series Getting Started Guide.
Each C1048P has 48 user ports, two uplink ports, and two stack-ports. When you connect multiple C1048Ps together through the stack
ports, they operate as a single unit with up to 384 front panel ports. The port extender stack operates and is managed as a single entity
through a C9000 Series switch.
When you connect multiple N20xx or N30xx series devices together through the stack ports, they operate as a single unit.
Provision individual port extenders by entering commands in PE Configuration mode from a C9010 console. The PE configuration is applied
to a port extender following its discovery and successful authentication by the parent C9010.
If the master unit in a PE stack fails, stack ownership transfers to the standby unit. If a standby unit fails, the stack master does not
experience interrupted operation. A new standby unit is elected from the other member units.
Topics:
• Stack Management Roles
• Stack Master Election
• Important Points to Remember
• PE Stack Configuration
• Configuring the Unused PE Uplink Ports as Front-End Ports
• Locating the Port Extender
• Troubleshooting a PE Stack
Stack Management Roles
After you assemble and cable a stack of port extenders and power the stack units on, the units receive the provisioned configuration from
the parent C9010. A stack master unit is elected based on the highest MAC address.
The master may occupy any position in the stack. The Master LED on the front panel is illuminated on the master unit.
The stack unit with the second highest MAC address is elected as the standby or backup management unit. The standby assumes the
master role if the master unit in the stack fails. The PE with the next highest priority or MAC address becomes standby. All remaining
stack units function as stack members.
Although the master and standby units are automatically selected by MAC address, you can configure PE priorities to specify which units
are assigned the master and standby roles.
Stack Master Election
When a PE stack reloads and all stack units come up, all units participate in the stack master election. The master and standby units are
chosen based on the priority or MAC address. The stack takes the MAC address of the master unit.
• Unit priority — The range is from 1 to 14. The unit with the highest priority is elected the master management unit; the unit with the
second highest priority is elected the standby unit. The default is 0. To remove a priority and set the priority to 0, enter the no
stack-unit unit-number priority command in PE CONFIGURATION mode.
• MAC address (if there is a priority tie) — By default, the unit with the highest MAC value becomes the master unit if no priorities
are configured.
A change in the stack master occurs when:
• You power down the stack master.
• A failover of the master switch occurs.
• You disconnect the master switch from the stack.
42
Port Extender (PE) Stacking 691