SV: conf size limits and functions / scripts / class possibilities

[Simon Hobson]

Karl Bloch Andersen wrote:

>Yes I really mean interfaces in the form of hardware units with 
>relay agents with 32 to 128 circuit ids, but then again it depends 
>on how you define interfaces :)
>And yes all with different subnets.
>
>
>There's 2 of the following statements pr interface with only the 
>first statement different
>
>As Lars wrote earlier (Wednesday)
>
>match if  packet ( (option agent.circuit-id) , 3,2)  = "21" AND
>
>match if  packet ( (option agent.circuit-id) , 5,2)  = "01" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "02" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "03" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "04" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "05" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "06" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "07" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "08" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "09" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "10" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "11" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "12" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "13" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "14" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "15" OR
>match if  packet ( (option agent.circuit-id) , 5,2)  = "16"
>THEN
>class = "class one"

Thinking more about this ...

What you have above won't work correctly - you need parentheses 
around the OR bits otherwise it will evaluate as :

(xx AND aa) OR bb OR cc ...

I think you also only need the one match if statement, as in :

match if  packet ( (option agent.circuit-id) , 3,2)  = "21" AND

      (    packet ( (option agent.circuit-id) , 5,2)  = "01" OR
           packet ( (option agent.circuit-id) , 5,2)  = "02" OR
           packet ( (option agent.circuit-id) , 5,2)  = "03" OR
           packet ( (option agent.circuit-id) , 5,2)  = "04" OR
           packet ( (option agent.circuit-id) , 5,2)  = "05" OR
           packet ( (option agent.circuit-id) , 5,2)  = "06" OR
           packet ( (option agent.circuit-id) , 5,2)  = "07" OR
           packet ( (option agent.circuit-id) , 5,2)  = "08" OR
           packet ( (option agent.circuit-id) , 5,2)  = "09" OR
           packet ( (option agent.circuit-id) , 5,2)  = "10" OR
           packet ( (option agent.circuit-id) , 5,2)  = "11" OR
           packet ( (option agent.circuit-id) , 5,2)  = "12" OR
           packet ( (option agent.circuit-id) , 5,2)  = "13" OR
           packet ( (option agent.circuit-id) , 5,2)  = "14" OR
           packet ( (option agent.circuit-id) , 5,2)  = "15" OR
           packet ( (option agent.circuit-id) , 5,2)  = "16"    )



If the software supported inequality operators then you could 
simplify things as :

match if  packet ( (option agent.circuit-id) , 3,2)  = "21" AND
           packet ( (option agent.circuit-id) , 5,2)  >= "01" AND
           packet ( (option agent.circuit-id) , 5,2)  <= "16"

How hard would it be to add '>' '<' '>=' and '<=' operators ?



I'll finish with a query for people more familiar with expressions 
and the internal workings :

Can we extract the packet bits into variables :
   gate_card=packet ( (option agent.circuit-id) , 3,2)
   gate_port=packet ( (option agent.circuit-id) , 5,2)

and then use these variables :
match if  gate_card  = "21" AND

      (    gate_port  = "01" OR
           gate_port  = "02" OR
           gate_port  = "03" OR
           gate_port  = "04" OR
           gate_port  = "05" OR
           gate_port  = "06" OR
           gate_port  = "07" OR
           gate_port  = "08" OR
           gate_port  = "09" OR
           gate_port  = "10" OR
           gate_port  = "11" OR
           gate_port  = "12" OR
           gate_port  = "13" OR
           gate_port  = "14" OR
           gate_port  = "15" OR
           gate_port  = "16"    )

And would this be more or less efficient in execution ?


Also, does the server do optimised logical operations ? Ie, in the 
example above, if the card is not 21, does it skip the other 16 
expressions ? This would make a huge difference in performance !

Simon