Cisco Catalyst 4500 Series Administration Guide

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Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)SG
OL-30933-01
Chapter 5 Configuring Virtual Switching Systems
Understanding Virtual Switching Systems
Scenario 1
The VSS System is configured as follows:
• Global IP address- GIP
• switch 1 IP address - IP1
• switch 2 IP address - IP2
In this scenario, if switch 1 enters recovery mode, it will use IP1 for the fa1 interface on switch 1.
Conversely, if switch 2 enters recovery mode, it will use IP2 for the fa1 interface on switch2.
Scenario 2
The VSS system is configured as follows:
• Global IP address - GIP
• switch 1 IP address - IP1
• switch 2 specific IP address
In this scenario, if switch 1 enters recovery mode, it will use IP1 for the fa1 interface on the switch 1.
Conversely, if switch 2 enters recovery mode, it will use GIP for the fa1 interface on switch2.
VSS Initialization
A VSS is formed when the two switches and the VSL link between them become operational. The peer
switch communicates over the VSL to negotiate the switches’ roles.
If only one switch becomes operational, it assumes the VSS Active role. The VSS forms when the second
switch becomes operational and both switches bring up their VSL interfaces.
VSS initialization is described in the following sections:
• Virtual Switch Link Protocol, page 5-26
• SSO Dependencies, page 5-27
• Initialization Procedure, page 5-27
Virtual Switch Link Protocol
The Virtual Switch Link Protocol (VSLP) consists of several protocols that contribute to virtual switch
initialization. The VSLP includes the following protocols:
• Role Resolution Protocol
The peer switch use Role Resolution Protocol (RRP) to negotiate the role (VSS Active or VSS
Standby) for each switch.
• Link Management Protocol
The Link Management Protocol (LMP) runs on all VSL links, and exchanges information required
to establish communication between the two switches.
LMP identifies and rejects any unidirectional links. If LMP flags a unidirectional link, the switch
that detects the condition brings the link down and up to restart the VSLP negotiation. VSL moves
the control traffic to another port if necessary.

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E