Chapter 11. High Availability
This chapter describes the high availability fault-tolerance feature in NetDefend Firewalls.
• Overview, page 489
• HA Mechanisms, page 491
• Setting Up HA, page 494
• HA Issues, page 498
• Upgrading an HA Cluster, page 500
• HA Advanced Settings, page 502
11.1. Overview
HA Clusters
NetDefendOS High Availability (HA) provides a fault tolerant capability to NetDefend Firewall
installations. HA works by adding a back-up slave NetDefend Firewall to an existing master
firewall. The master and slave are connected together and make up a logical HA Cluster. One of the
units in a cluster will be active when the other unit is inactive and on standby.
Initially, the cluster slave will be inactive and will only monitor the activity of the master. If the
slave detects that the master has become inoperative, an HA failover takes place and the slave
becomes active, assuming processing responsibility for all traffic. If the master later becomes
operative again, the slave will continue to be active but the master will now monitor the slave with
failover only taking place if the slave fails. This is sometimes known as an active-passive
implementation of fault tolerance.
Note: High Availability is only available on some NetDefend
models
The HA feature is only available on the D-Link NetDefend DFL-1600, 1660, 2500,
2560 and 2560G.
The Master and Active Units
When reading this section on HA, it should be kept in mind that the master unit in a cluster is not
always the same as the active unit in a cluster.
The active unit is the NetDefend Firewall that is actually processing all traffic at a given point in
time. This could be the slave unit if a failover has occurred because the master is no longer
operational.
Interconnection of Cluster Units
In a cluster, the master and slave units must be directly connected to each other by a synchronization
connection which is known to NetDefendOS as the sync interface. One of the normal interfaces on
the master and the slave are dedicated for this purpose and are connected together with a crossover
cable.
Special packets, known as heartbeats, are continually sent by NetDefendOS across the sync
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Summary of Contents for DFL-1600 - Security Appliance
Page 27: ...1 3 NetDefendOS State Engine Packet Flow Chapter 1 NetDefendOS Overview 27 ...
Page 79: ...2 7 3 Restore to Factory Defaults Chapter 2 Management and Maintenance 79 ...
Page 146: ...3 9 DNS Chapter 3 Fundamentals 146 ...
Page 227: ...4 7 5 Advanced Settings for Transparent Mode Chapter 4 Routing 227 ...
Page 241: ...5 4 IP Pools Chapter 5 DHCP Services 241 ...
Page 339: ...6 7 Blacklisting Hosts and Networks Chapter 6 Security Mechanisms 339 ...
Page 360: ...7 4 7 SAT and FwdFast Rules Chapter 7 Address Translation 360 ...
Page 382: ...8 3 Customizing HTML Pages Chapter 8 User Authentication 382 ...
Page 386: ... The TLS ALG 9 1 5 The TLS Alternative for VPN Chapter 9 VPN 386 ...
Page 439: ...Figure 9 3 PPTP Client Usage 9 5 4 PPTP L2TP Clients Chapter 9 VPN 439 ...
Page 450: ...9 7 6 Specific Symptoms Chapter 9 VPN 450 ...
Page 488: ...10 4 6 Setting Up SLB_SAT Rules Chapter 10 Traffic Management 488 ...
Page 503: ...11 6 HA Advanced Settings Chapter 11 High Availability 503 ...
Page 510: ...12 3 5 Limitations Chapter 12 ZoneDefense 510 ...
Page 533: ...13 9 Miscellaneous Settings Chapter 13 Advanced Settings 533 ...