Cisco Cisco IOS Software Release 12.2(14)ZA
Features
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Cisco IOS Release 12.2(14)ZA7
Sticky connections also permit the coupling of services that are handled by more than one virtual server
or firewall farm. This option allows connection requests for related services to use the same real server.
For example, web server (HTTP) typically uses TCP port 80, and HTTPS uses port 443. If HTTP virtual
servers and HTTPS virtual servers are coupled, connections for ports 80 and 443 from the same client
IP address or subnet are assigned to the same real server.
or firewall farm. This option allows connection requests for related services to use the same real server.
For example, web server (HTTP) typically uses TCP port 80, and HTTPS uses port 443. If HTTP virtual
servers and HTTPS virtual servers are coupled, connections for ports 80 and 443 from the same client
IP address or subnet are assigned to the same real server.
Virtual servers that are in the same sticky group are sometimes called buddied virtual servers.
GPRS load balancing and the Home Agent Director do not support sticky connections.
TCP Session Reassignment
IOS SLB tracks each TCP SYN sent to a real server by a client attempting to open a new connection. If
several consecutive SYNs are not answered, or if a SYN is replied to with an RST, the TCP session is
reassigned to a new real server. The number of SYN attempts is controlled by a configurable reassign
threshold.
several consecutive SYNs are not answered, or if a SYN is replied to with an RST, the TCP session is
reassigned to a new real server. The number of SYN attempts is controlled by a configurable reassign
threshold.
IOS SLB firewall load balancing does not support TCP session reassignment.
Transparent Web Cache Load Balancing
IOS SLB can load-balance HTTP flows across a cluster of transparent web caches. To set up this
function, configure the subnet IP addresses served by the transparent web caches, or some common
subset of them, as virtual servers. Virtual servers used for transparent web cache load balancing do not
answer pings on behalf of the subnet IP addresses, and they do not affect traceroute.
function, configure the subnet IP addresses served by the transparent web caches, or some common
subset of them, as virtual servers. Virtual servers used for transparent web cache load balancing do not
answer pings on behalf of the subnet IP addresses, and they do not affect traceroute.
In some cases, such as when its cache does not contain needed pages, a web cache might need to initiate
its own connections to the Internet. Those connections should not be load-balanced back to the same set
of web caches. To address this need, IOS SLB allows you to configure client exclude statements, which
exclude connections initiated by the web caches from the load-balancing scheme.
its own connections to the Internet. Those connections should not be load-balanced back to the same set
of web caches. To address this need, IOS SLB allows you to configure client exclude statements, which
exclude connections initiated by the web caches from the load-balancing scheme.
IOS SLB firewall load balancing does not support transparent web cache load balancing.
Security Features
IOS SLB provides the following security features:
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