R3102-R3103-HP 6600/HSR6600 Routers High Availability Configuration Guide

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Configuring stateful failover
The following matrix shows the feature and router compatibility:
Feature
6602
HSR6602
6604/6608/6616
Stateful failover
Yes
Yes
No
Stateful failover overview
Some customers require the key entries or access points of their networks, such as the Internet access
point of an enterprise or a database server of a bank, to be highly reliable to ensure continuous data
transmission. Deploying only one device (even with high reliability) in such a network risks a single
point of failure, as shown in Figure 52. Stateful failover can solve this problem.
Figure 52 Network with one device deployed
Operating procedure
Stateful failover involves service backup and traffic switchover. Stateful failover works as follows:
1. As shown in Figure 53, Device A and Device B connect to each other over a failover link.
2. The two devices exchange state negotiation messages periodically through the failover link.
After the two devices enter the synchronized state, they back up the sessions of each other to
make sure that the sessions on them are consistent.
3. If one device fails, the other device can take over the services by using VRRP or a dynamic
routing protocol (such as OSPF) to avoid service interruption.
In this document, the stateful failover feature supports backing up portal services.
Internet
Internal
network
Device
Host A Host B