User guide

17-24 E
XTREME
W
ARE
S
OFTWARE
U
SER
G
UIDE
S
ERVER
L
OAD
B
ALANCING
(SLB)
S
ERVICE
-C
HECK
Service-check is Layer 7 based application-dependent checking defined on a VIP.
Service-checking is performed on each node in the pool with which this VIP is
associated. The default frequency is 60 seconds and the default timeout is 180 seconds.
Each service check has associated parameters that you can set. These parameters are
described in Ta bl e 1 7 - 3.
If the service-check parameters are not specified on an individual node or VIP, the
global default values for these parameters are used. The global service-check defaults
themselves are configurable, so if you use the same value in many cases, change the
global defaults accordingly.
In the case of HTTP service-checking, the URL of the Web page to be retrieved, such as
“/index.html”, can be specified. A match-string that is expected to be in the retrieved
Web page can be specified, such as “Welcome”. If the match-string is found in the first
1,000 bytes of the retrieved Web page, the service-check passes on the particular node. A
match-string specified as keyword any-content will match any retrieved text. However,
to distinguish valid data in the retrieved text from error text, specifying an actual string
to match is suggested.
For FTP, Telnet, and POP3 service-check attempts to log on and off the application on
the server using the specified userid and password.
Table 17-3: Service-Check Parameters
Service Attribute Global Default Value
HTTP URL
Match-string
“/”
Any-content
FTP Userid
Password
“anonymous”
“anonymous”
Telnet Userid
Password
“anonymous”
“anonymous”
SMTP Dns-domain Same as the switch DNS domain. If
no DNS domain is configured for the
switch, the value is ““.
NNTP Newsgroup “ebusiness”
POP3 Userid
Password
“anonymous”
“anonymous”