Nortel Networks WEB OS 212777 - Manual (Page 224)

Web OS 10.0 Application Guide
224 n Chapter 10: Health Checking
212777-A, February 2002
TCP Health Checks
TCP health checks are useful in verifying user-specific TCP applications that cannot be
scripted.
Session switches monitor the health of servers and applications by sending Layer 4 connection
requests (TCP SYN packets) for each load-balanced TCP service to each server in the server
group on a regular basis. The rate at which these connection requests are sent is a user-config-
urable parameter. These connection requests identify both failed servers and failed services on
a healthy server. When a connection request succeeds, the session switch quickly closes the
connection by sending a TCP FIN (finished) packet.
N OTE – TCP health check is a default health check after you have configured the switch for a
particular service.
ICMP Health Checks
Configure the switch with ICMP health check to verify if the real server is alive. The Layer 3
echo - echo reply health check is used for UDP services or when ICMP health checks are
configured.
1. Select the health check menu for group 1.
2. Set the health check type to ICMP for group 1.
3. Apply and save your configuration.
>> # /cfg/slb/group 1
>> # Real server group 1# health icmp
>> # Real server group 1# apply