Cisco Catalyst 2950 Command Reference

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Catalyst 2950 and Catalyst 2955 Switch Command Reference
0L-10102-01
Chapter 2 Catalyst 2950 and 2955 Cisco IOS Commands
spanning-tree extend system-id
spanning-tree extend system-id
Use the spanning-tree extend system-id global configuration command to enable the extended system
ID feature.
spanning-tree extend system-id
Note Though visible in the command-line help strings, the no version of this command is not supported. You
cannot disable the extended system ID feature.
Syntax Description This command has no arguments or keywords.
Defaults The extended system ID is enabled.
Command Modes Global configuration
Command History
Usage Guidelines In Cisco IOS Release 12.1(9)EA1 and later, Catalyst 2950 switches support the IEEE 802.1t
spanning-tree extensions, and some of the bits previously used for the switch priority are now used for
the extended system ID (VLAN identifier for the per-VLAN spanning-tree plus [PVST+] and for rapid
PVST+ or an instance identifier for the multiple spanning tree [MST]). In earlier releases, the switch
priority is a 16-bit value.
The spanning tree uses the extended system ID, the switch priority, and the allocated spanning-tree MAC
address to make the bridge ID unique for each VLAN or multiple spanning-tree instance. With earlier
releases, spanning tree used one MAC address per VLAN to make the bridge ID unique for each VLAN.
Support for the extended system ID affects how you manually configure the root switch, the secondary
root switch, and the switch priority of a VLAN. For more information, see the “spanning-tree mst root”
and the “spanning-tree vlan” sections.
If your network consists of switches that do not support the extended system ID and switches that do
support it, it is unlikely that the switch with the extended system ID support will become the root switch.
The extended system ID increases the switch priority value every time the VLAN number is greater than
the priority of the connected switches running older software.
Release Modification
12.1(9)EA1 This command was introduced.

Cisco Catalyst 2950 Specifications

General

Forwarding Bandwidth	8.8 Gbps
Switching Capacity	13.6 Gbps
Forwarding Rate	6.6 Mpps
Weight	3.6 kg
RAM	16 MB
Flash Memory	8 MB
Operating Humidity	10% to 85% non-condensing
Uplink Ports	2 x 10/100/1000Base-T
Dimensions	4.4 cm x 44.5 cm x 24.2 cm
Remote Management Protocol	SNMP, Telnet, HTTP
Features	Quality of Service (QoS), VLAN support
Compliant Standards	IEEE 802.3, IEEE 802.3u, IEEE 802.1D, IEEE 802.1Q, IEEE 802.1p
Status Indicators	system
Operating Temperature	0 to 45°C
Ports	24 x 10/100 Ethernet ports
MAC Address Table Size	8, 192 entries
Power Supply	Internal 100-240V AC, 50-60Hz