Cisco Catalyst 2900 Series XL Especificaciones descargar pdf (Pagina 104)

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Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide

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Chapter 5 Clustering Switches

Planning a Switch Cluster

HSRP and Standby Command Switches

The switch supports Hot Standby Router Protocol (HSRP) so that you can configure a group of standby

command switches. Because a command switch manages the forwarding of all communication and

configuration information to all the member switches, we strongly recommend that you configure a

cluster standby command switch to take over if the primary command switch fails.

A cluster standby group is a group of command-capable switches that meet the requirements described

in the “Standby Command Switch Characteristics” section on page 5-3. Only one cluster standby group

can be assigned per cluster.

Note • When the command switch is a Catalyst 3550 switch, all standby command switches must be

Catalyst 3550 switches or Catalyst 2950 switches running Cisco IOS Release 12.1(6)EA2 or

later.

• When the command switch is a Catalyst 2950 switch running Cisco IOS Release 12.1(6)EA2 or

later, all standby command switches must be Catalyst 2950 switches running Cisco IOS

Release 12.1(6)EA2 or later.

• When the Catalyst 2950 command switch is running Cisco IOS Release 12.0(5)WC2 or earlier, the

standby command switches can be these switches also running Cisco IOS Release 12.0(5)WC2 or

earlier: Catalyst 2900 XL, Catalyst 2950, andCatalyst 3500 XL switches.

Note The cluster standby group is an HSRP group. Disabling HSRP disables the cluster standby group.

Note The switches in the cluster standby group are ranked according to HSRP priorities. The switch with

the highest priority in the group is the active command switch (AC). The switch with the next highest

priority is the standby command switch (SC). The other switches in the cluster standby group are the

passive command switches (PC). If the active command switch and the standby command switch

become disabled at the same time, the passive command switch with the highest priority becomes the

active command switch. For the limitations to automatic discovery, see the “Automatic Recovery of

Cluster Configuration” section on page 5-11. For information about changing HSRP priority values,

refer to the standby priority interface configuration mode command in the Cisco IOS Release 12.0

documentation set. The HSRP standby hold time interval should be greater than or equal to 3 times

the hello time interval. The default HSRP standby hold time interval is 10 seconds. The default HSRP

standby hello time interval is 3 seconds. For more information about the standby hold time and hello

time intervals, refer to the Cisco IOS Release 12.0 documentation set on Cisco.com.

These connectivity guidelines ensure automatic discovery of the switch cluster, cluster candidates,

connected switch clusters, and neighboring edge devices. These topics also provide more detail about

standby command switches:

• “Virtual IP Addresses” section on page 5-11

• “Automatic Recovery of Cluster Configuration” section on page 5-11

• “Considerations for Cluster Standby Groups” section on page 5-12

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Cisco Catalyst 2900 Series XL Especificaciones Pagina 104