Data Center LAN Migration Guide - Juniper Networks

For more detailed information on NIC teaming using VMware Infrastructure 3, refer to:
www.vmware.com/technology/virtual-networking/virtual-networks.html
www.vmware.com/files/pdf/virtual_networking_concepts.pdf
Data Center LAN Migration Guide
The main advantages to the inverted U design are that all ports on the aggregation switches have useable bandwidth
100% of the time, traffic flows between access and aggregation are always deterministic, and there is a deterministic
latency to all Virtual Chassis connected to a single aggregation or core switch.
Redundant Trunk Groups
LAN designs using the EX4200 Ethernet Switch with Virtual Chassis technology also benefit from RTG protocol as a
built-in, optimized replacement to STP for sub-second convergence and automatic load balancing.
RTG is an HA link feature of the EX Series Ethernet Switches that eliminates the need for STP. In fact, STP can’t be
provisioned on an RTG link. Ideally implemented on a switch with a dual-home connection, RTG configures one link
as active and forwarding traffic, and the other link as blocking and backup to the active link. RTG provides extremely
fast convergence in the event of a link failure. It is similar in practice to Rapid Spanning Tree Protocol (RSTP) root and
alternate port, but doesn’t require an RSTP configuration.
Layer Three Uplinks
Another alternative is to use L3 uplinks from the access layer to the aggregation/core switches. This limits L2 domain and
VLANs to a single Virtual Chassis. Equal-cost multipath (ECMP), which is included in the base license for L3 OSPF on
EX Series data center switches, is used for uplinks. An advanced license is needed if BGP, IS-IS, or Ipv6 are required. Up
to 480 servers can be provisioned with one EX4200 Virtual Chassis. This allows applications to maintain L2 adjacency
within a single switch, however servers are typically collocated within a single row which is part of the Virtual Chassis. The
VLAN boundary is the access layer for low latency application data transfer. Virtual Chassis extension would allow distant
servers to be accommodated as well. These servers would be part of a single Virtual Chassis domain.
Virtual Chassis Best Practices
These best practices should be followed when deploying and operating the EX4200 at the access layer:
• When designing a Virtual Chassis configuration, consider a deployment in which ports are distributed across as many
switches as possible to provide the highest resiliency and the smallest failure domain.
• When possible, place uplink modules in the Virtual Chassis configuration line card switches, and place uplinks in
devices which are separated at equal distances by member hop.
• Use the virtual management Ethernet (VME) interface as the management interface to configure Virtual Chassis
technology options.
• Evenly space master and backup switches by member hop when possible.
• When installing a Virtual Chassis configuration, explicitly configure the mastership priority of the members that you
want to function as the master and backup switches.
• When removing a switch from a Virtual Chassis configuration, immediately recycle its member ID so that the ID
becomes the next lowest available unused ID. In this way, the replacement switch automatically is assigned that
member ID and inherits the configuration of the original switch.
• Specify the same mastership priority value for the master and backup switches in a Virtual Chassis configuration.
• Configure the highest possible mastership priority value (255) for the master and backup switches.
• Place the master and backup switches in separate locations when deploying an extended Virtual Chassis
configuration.
• For maximum resiliency, interconnect Virtual Chassis member devices in a ring topology.
• When changing configuration settings on the master switch, propagate changes to all other switches in the Virtual
Chassis configuration via a “commit sync” command.
Refer to Juniper’s Virtual Chassis Technology Best Practices Implementation Guide for more information:
www.juniper.net/us/en/products-services/switching/ex-series/ex4200/#literature.
Copyright © 2012, Juniper Networks, Inc. 35