SLB Health Check Types
Using the /cfg/slb/group/health command, you can specify the type of health check for the group of real servers.
 
>> Real Server Group 1# health
Current health check type: tcp
Pending new health check type: sip
Enter health check type:
The health check options are described in the following table. For a more detailed description of these health check options, refer to the Alteon Command Line Interface Application Guide.
 
SLB Health Check Types (/cfg/slb/group/health) 
Type and Description
arp
 
Sends an ARP request for Layer 2 health checking.
clusthcfr
 
The clusthcfr health check aggregates the virtual service status of cluster members at regular intervals.
The clusthcfr health check is set internally by Alteon and is not configurable by the user.
clusthcme
 
The clusthcme health check enables and disables remote server status updates from the cluster front end.
The clusthcme health check is set internally by Alteon and is not configurable by the user.
dhcp
 
Sets the health check type to dhcp.
This health check type can operate with or without content. The following content types can be configured:
*request — Use a DHCP request instead of an inform packet.
*srequest — Use a DHCP request with a source port of 68.
*strict — Use DHCP information, but with a source port of 68.
If no content is specified, this indicates using a DHCP inform with the UDP offset source port.
dns
 
Checks that the domain name specified in the /cfg/slb/group/content command can be resolved by the server.
dssp
 
The Distributed Site Selection Protocol (DSSP) is a proprietary protocol that resides above TCP. DSSP enables the sending and receiving of remote site updates. GSLB sites interact using DSSP. The DSSP health check is a predefined health check for use with remote real servers.
When the health check for a remote real server is set to DSSP, the remote site status is controlled by DSSP updates. The result of a DSSP health check is based on updates received for the remote site.
The DSSP health check is set internally by Alteon and is not configurable by the user.
For health monitoring via DSSP, enable DSSP on both the local and remote Alteon. Radware recommends that you configure the same remote site update interval on both sites, and that you use the DSSP health check only with remote real servers that are Alteon devices.
The DSSP health check marks a remote real server as “DOWN” when GSLB is changed to “OFF”, or when there is a change in the remote site configuration.
When a GSLB site 2 is configured to send DSSP updates to a GSLB site 1, Alteon marks site 2 as “UP” if site 1 receives updates from a site 2.
If site 1 does not receive an update from site 2, Alteon marks site 2 as “FAILED.”
Note: Even if a GSLB site is “UP,” there may be no available services for that site.
ftp
 
For FTP services, checks that the filename specified in the /cfg/slb/group/content command is accessible on the server through anonymous login.
http(s)
 
For the HTTP service, use HTTP/1.1 GET when a host header is required, to check that the URL content is specified in the /cfg/slb/group/content command. Otherwise, an HTTP/1.0 GET occurs. HTTP health check is successful if you get a return code of 200.
Note: If content is not specified, the health check is performed using the / character.
icmp
 
For Layer 3 health checking, pings the server.
imap
 
For user mail service, checks that the user:password value specified in the /cfg/slb/group/content command exists on the server.
ldap(s)
 
Sets the health check type to LDAP.
LDAP health checks enable Alteon to determine if the LDAP server is alive. This health check consists of three LDAP messages over one TCP connection: a bind request, a bind result, and an unbind request.
Alteon sends an anonymous bind request to the server. If the server is up, it sends the bind result message and Alteon marks the server as alive. Alteon must send an unbind request so that the server does not hold resources indefinitely. The administrator can choose LDAP version 2 or 3, as both versions are compatible with Alteon.
Configure Username, Password, and Base Distinguish Name arguments in the health check parameters or group content parameters in the LDAP message format: cn=<username>,dc=<base-part1>,dc=<base-part2>,dc=<base-part3>:<password>.
nntp
 
For newsgroup services, checks that the newsgroup name specified in the /cfg/slb/group/content command is accessible on the server.
pop3
 
For user mail service, checks that the user:password account specified in the /cfg/slb/group/content command exists on the server.
radius
 
For RADIUS remote access server authentication, checks that the user:password value specified in the /cfg/slb/group/content command exists in Alteon and the server.
To perform application health checking to a RADIUS server, the network administrator must also configure the /cfg/slb/advhc/secret parameter (see /cfg/slb/advhc Advanced Health Check Menu). The secret value is a field of up to 32 alphanumeric characters used by Alteon to encrypt a password during the execution of the RSA Message Digest Algorithm (MD5), and by the RADIUS server to decrypt the password during verification.
rtsp
 
Sets the health check type to RTSP.
The RTSP health check can operate with or without content. If there is no content configured, Alteon issues an RTSP OPTIONS method. If content is supplied, Alteon issues an RTSP DESCRIBE method. If the response to either method is RTSP/200, then the health check passes. If this is not the response, the health check fails.
script
 
Enables using script-based health checks in a send/expect format to check for application and content availability.
sip
 
Sets the health check type to SIP.
You can perform the SIP (Session Initiation Protocol) health checks by using an SIP PING request. You must enable UDP to perform SIP load balancing.
smtp
 
For mail-server services, checks that the user specified in the /cfg/slb/group/content command is accessible on the server.
snmp
 
Enables using SNMP-based health checks.
sslhello
 
Enables Alteon to query the health of the SSL servers by sending an SSL client Hello packet, and then verify the contents of the server’s Hello response. During the handshake, the user and server exchange security certificates, negotiate an encryption and compression method, and establish a session ID for each session.
tcp
 
Opens and closes a TCP/IP connection to the server for TCP service.
tftp
 
Sets the health check type to TFTP.
This protocol enables the user to request a file from the server. At regular intervals, Alteon transmits TFTP read requests (RRQ) to all servers in the group. The health check is successful if the server responds to the RRQ. The health check fails if Alteon receives an error packet from the real server.
udp
 
Enables health checking using UDP queries.
wap
 
Enables health checking using WAP queries. The following WAP types are supported: WSP, WTP, WTLS-WSP, and WTLS-WTP.
*WSP enables connectionless WSP content health checks for WAP gateways. The content under /cfg/slb/adv/waphc (see /cfg/slb/advhc Advanced Health Check Menu) must also be configured.
*WTP enables connection-oriented WTP+WSP content health checks for WAP gateways. The content under /cfg/slb/adv/waphc (see /cfg/slb/advhc Advanced Health Check Menu) must also be configured.
*WTLS provides Wireless Transport Layer Security (WTLS) Hello-based health checks for encrypted and connection-oriented WTLS traffic on port 9203.
wts
 
Sets the health check type to WTS.
logexp
 
Sets a logical expression between health checks.