Dell 3-DNS Especificaciones descargar pdf (Pagina 139)

Rules

BIG-IP® Reference Guide 4-59

• Subjects that stay the same are called constant operands.

A question, or expression, asks questions about variable operands by

comparing their current value to constant operands with relational operators.

Constant operands

Possible constant operands are:

◆ IP protocol constants, for example:

UDP or TCP

◆ IP addresses expressed in masked dot notation, for example:

206.0.0.0 netmask 255.0.0.0

◆ Strings of ASCII characters, for example:

pictures/bigip.gif

◆ Regular expression strings

Variable operands (variables)

Since variable operands change their value, they need to be referred to by a

constant descriptive name. The variables available depend on the context in

which the rule containing them is evaluated. Possible variable operands are:

◆ IP packet header variables, such as:

• client_addr. Used by a client to represent a source IP address. This

variable is replaced with an unmasked IP address.

• server_addr. Used to represent a destination IP address. This variable

is replaced with an unmasked IP address. The server_addr variable is

used to represent the destination address of the packet. This variable is

useful when load balancing traffic to a wildcard virtual server.

• client_port. Used to represent a client port number.

• server_port. Used to represent a server port number.

• ip_protocol. Used to represent an IP protocol. This variable is

replaced with a numeric value representing an IP protocol such as

TCP, UDP, or IPSEC.

• link_qos. Used to represent the Quality of Service (QoS) level.

• ip_tos. Used to represent that Type of Service (ToS) level.

◆ HTTP request strings

All HTTP request string variables are replaced with string literals. HTTP

request variables are referred to in command line syntax by a predefined

set of names. Internally, an HTTP request variable points to a method for

extracting the desired string from the current HTTP request header data.

Before an HTTP request variable is used in a relational expression, it is

replaced with the extracted string.

The evaluation of a rule is triggered by the arrival of a packet. Therefore,

variables in the rule may refer to features of the triggering packet. In the

1 2 ... 134 135 136 137 138 139 140 141 142 143 144 ... 425 426

Sin comentarios

Dell 3-DNS Especificaciones Pagina 139