User guide

E
XTREME
W
ARE
S
OFTWARE
U
SER
G
UIDE
17-25
H
EALTH
C
HECKING
For SMTP, service-check identifies the identity of the switch by providing the specified
DNS domain. The SMTP server might not even use the specified DNS domain for
authentication, only identification.
For NNTP, service-check queries the newsgroup specified.
Because service-checking is configured on a VIP basis, and multiple VIPs can use the
same nodes, and you can run multiple service-checks against a particular node IP
address and port number. It is possible for some of these service-checks to fail, while
others pass. Therefore, when determining if a given node can accept a new connection
for a VIP, the node must have passed the service-check configured for that VIP. When
showing detailed VIP information, the status for individual nodes is shown with respect
to that VIP.
S
ERVICE-CHECK COMMANDS
To enable service-check, use this command:
enable slb vip [<vipname> | all] service-check
To disable service-check, use this command:
disable slb vip [<vipname> | all] service-check
E
XTERNAL
H
EALTH
C
HECKING
For server health checking that goes beyond the abilities of internal health checking, the
switch also supports external health checking. The external health checking device
sends the results of its check to the switch by way of SNMP MIB attributes. The specific
MIB definitions for external health checking are available on the Extreme Networks Web
site at: http://www.extremenetworks.com/extreme/support/otherapps.htm.
M
AINTENANCE
M
ODE
A node or VIP can be put into “maintenance mode” by simply disabling the node or
VIP. In maintenance mode, existing connections remain active, but no new connections
are permitted. The existing connections are either closed by the client and server, or are
aged out if idle for more than 600 seconds.