Juniper Networks EX2500 - Manual (Page 93)

High Availability Overview „ 79
Chapter 8
High Availability Through Uplink Failure
Detection
This chapter describes how to use Uplink Failure Detection (UFD) to ensure that
network resources remain available if one switch is removed for service.
The following topics are discussed in this chapter:
„ High Availability Overview on page 79
„ Failure Detection Pair on page 80
„ Spanning Tree Protocol with UFD on page 80
„ UFD Configuration Guidelines on page 80
„ UFD Configuration Example on page 81
„ Monitoring UFD on page 81
High Availability Overview
The EX2500 switch supports high-availability network topologies.
Uplink Failure Detection (UFD) is designed to support Network Adapter Teaming.
Network Adapter Teaming allows all the network interface cards (NICs) on each
server to share the same IP address. The NICs are configured into a team. One NIC
is the primary link, and the other is a standby link.
UFD allows the switch to monitor specific ports (Link to Monitor ports) to detect
link failures. When the switch detects a link failure, it automatically disables specific
ports (Link to Disable ports). Each corresponding server’s network adapter can
detect the disabled port and trigger a network-adapter failover to another port on
the switch.
The switch automatically enables the control ports when the monitor ports return
to service.
Figure 14 on page 80 shows a basic UFD configuration, with a Failure Detection
Pair (FDP) that consists of one LtM (Link to Monitor) and one LtD (Link to Disable).
When the switch detects a link failure in the LtM, it disables the ports in the LtD.
The servers detect the disabled ports, which triggers a NIC failover.