Installation guide

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Device Manager Guide, Cisco ACE 4700 Series Application Control Engine Appliance
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Chapter 5 Configuring Virtual Servers
Configuring Virtual Servers
Table 5-12 Predictor Methods and Attributes
Predictor Method Description / Action
Hash Address The ACE selects the server using a hash value based on the source or destination IP address.
To configure the hash address predictor method:
1. In the Mask Type field, indicate whether server selection is based on the source IP address or the
destination IP address:
– N/A—Indicates that this option is not defined.
– Destination—Indicates that the server is selected based on the destination IP address.
– Source—Indicates that the server is selected based on the source IP address.
2. In the IP Netmask field, select the subnet mask to apply to the address. If none is specified, the
default is 255.255.255.255.
Hash Content The ACE selects the server by using a hash value based on the specified content string of the HTTP
packet body.
1. In the Begin Pattern field, enter the beginning pattern of the content string and the pattern string
to match before hashing. If you do not specify a beginning pattern, the ACE starts parsing the
HTTP body immediate following the offset byte. You cannot configure different beginning and
ending patterns for different server farms that are part of the same traffic classification.
Valid entries are unquoted text strings with no spaces and a maximum of 255 alphanumeric
characters. The ACE supports regular expressions for matching string expressions. Table 12-33
lists the supported characters that you can use for matching string expressions.
2. In the End Pattern field, enter the pattern that marks the end of hashing. If you do not specify either
a length or an end pattern, the ACE continues to parse the data until it reaches the end of the field
or the end of the packet, or until it reaches the maximum body parse length. You cannot configure
different beginning and ending patterns for different server farms that are part of the same traffic
classification.
Valid entries are unquoted text strings with no spaces and a maximum of 255 alphanumeric
characters. The ACE supports regular expressions for matching string expressions. Table 12-33
lists the supported characters that you can use for matching string expressions.
3. In the Length field, enter the length in bytes of the portion of the content (starting with the byte
after the offset value) that the ACE uses for sticking the client to the server. Valid entries are
integers from 1 to 1000 bytes.
The offset and length can vary from 0 to 1000 bytes. If the payload is longer than the offset but
shorter than the offset plus the length of the payload, the ACE sticks the connection based on that
portion of the payload starting with the byte after the offset value and ending with the byte
specified by the offset plus the length. The total of the offset and the length cannot exceed 1000.
You cannot specify both the length and the end-pattern options for a Hash Content predictor.
4. In the HTTP Content Offset field, enter the portion of the content that the ACE uses to stick the
client on a particular server by indicating the bytes to ignore starting with the first byte of the
payload. Valid entries are integers from 0 to 999 bytes. The default is 0, which indicates that the
ACE does not exclude any portion of the content.
Hash Cookie The ACE selects the server by using a hash value based on the cookie name.
In the Cookie Name field, enter a cookie name in the form of an unquoted text string with no spaces
and a maximum of 64 characters.