Cisco Cisco IOS Software Release 12.2(18)SXE

You can also flag a probe as a routed probe, with the following considerations:

Only one instance of a routed probe per server farm can run at any given time.

Outbound packets for a routed probe are routed directly to a specified IP address.

IOS SLB probes use the SA Agent. You might want to specify the amount of memory that the SA Agent 
can use, using the rtr low-memory command. If the amount of available free memory falls below the 
value specified in the rtr low-memory command, then the SA Agent does not allow new operations to 
be configured. Refer to the description of the rtr low-memory command in the Cisco IOS Configuration 
Fundamentals Command Reference, Release 12.2 for more details.

Probes determine the status of each real server in a server farm. All real servers associated with all virtual 
servers tied to that server farm are probed.

If a real server fails for one probe, it is failed for all probes. After the real server recovers, all probes 
must acknowledge its recovery before it is restored to service.

Probes detect firewall failures. All firewalls associated with the firewall farm are probed.

If a firewall fails for one probe, it is failed for all probes. After the firewall recovers, all probes must 
acknowledge its recovery before it is restored to service.

Make sure you configure the HTTP probe to expect status code 401, to eliminate password problems. 
Refer to the description of the expect command in the 

 for 

more details.

Use the ip http server command to configure an HTTP server on the device. Refer to the description of 
the ip http server command in the Cisco IOS Configuration Fundamentals Command Reference, Release 
12.2 for more details.

In a transparent web cache load-balancing environment, an HTTP probe uses the real IP address of the 
web cache, since there is no virtual IP address configured.

IOS SLB provides the following protocol support features:

IOS SLB supports the following protocols:

Domain Name System (DNS)

Encapsulation Security Payload (ESP)

File Transfer Protocol (FTP)

Generic Routing Encapsulation (GRE)

GPRS Tunneling Protocol v0 (GTPv0)