Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual page 1179

Understanding the Full Mesh EX8200 Virtual Chassis Topology
Understanding the Ring EX8200 Virtual Chassis Topology
Copyright © 2010, Juniper Networks, Inc.
Chapter 44: EX8200 Virtual Chassis—Overview, Components, and Configurations
Role of XRE200 External Routing Engine Redundancy in a Virtual Chassis
Topology on page 1076
EX8200 Virtual Chassis Basic Topology on page 1076
We recommend that you use a full mesh topology for all EX8200 Virtual Chassis whenever
possible.
In a full mesh topology, every possible VCP connection within the Virtual Chassis is
established. Both external Routing Engines have connections to both switches in addition
to having connections to each other. The switches are connected together by a
user-configured VCP link—preferably multiple VCP links, which will automatically form
a VCP link aggregation group (LAG)—to provide another link for Virtual Chassis Control
Protocol (VCCP) traffic within the Virtual Chassis.
Figure 24 on page 1075 shows a full mesh EX8200 Virtual Chassis topology.
Figure 24: EX8200 Virtual Chassis Full Mesh Topology
Master External
Routing Engine
EX8200
Member switch
A full mesh Virtual Chassis topology has several advantages over other topologies.
Because there are multiple paths to all devices in the Virtual Chassis, a single link failure
does not disable any path from one device to another. Because the multiple VCP links
connect all devices together, the VCCP has more flexibility when sending control traffic
through the Virtual Chassis than it does in other topologies.
In a ring topology, each device in the EX8200 Virtual Chassis has at least one path to
every other device in the Virtual Chassis. The paths are not necessarily direct and might
require multiple hops between devices.
Backup External
Routing Engine
EX8200
Member switch
1075