Persistence cookie F5 LTM

NOTE: This entry is to be completed!

The BIG-IP combines the two encoded values and inserts them into the persistence cookie. For example, using the IP address and port 10.1.1.100:8080 as encoded above, the persistence value BIG-IP LTM encodes in the cookie is as follows:

1677787402.36895.0000

Note: The field following the port encoding is reserved for future use, and always contains four zeros as placeholders.

Decoding persistence cookie values

You can decode the cookie value by reversing the encoding algorithms detailed above.

For example, using the IP address and port 10.1.1.100:8080 as encoded above, the persistence value BIG-IP LTM encodes in the cookie is as follows:

1677787402.36895.0000

The first field in the cookie references the IP address of the destination server.

1.Convert the the decimal value 1677787402 to its 4-byte hexadecimal equivalent:

0x6401010A
2.Split into four hexadecimal bytes and reverse the byte order:

0x0A 0x01 0x01 0x64
3.Convert each 1-byte hexadecimal value to its equivalent decimal value, one per octet:

10.1.1.100
The second field in the cookie references the port of the destination server.

1.Convert the decimal value 36895 to the equivalent 2-byte hexadecimal value:

0x901F
2.Reverse the order of the 2 hexadecimal bytes:

0x1F90
3.Convert the resulting 2-byte hexadecimal value to its decimal equivalent:

8080

http://www.f5.com/pdf/white-papers/cookies-sessions-persistence-wp.pdf

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