Monday, November 10, 2008

Interrupt Context Switching Vs Process Switching

Process Switching
Process switching is the default switching technique used by all cisco routers and ios. According to process switching when the packet comes from media to the interface it will check the following steps given below:-
1) Check the destination address in the routing table.
2) Look for the recursive lookup or find the directly connected outgoing interface.
3) Mac rewrite for the next hop.
For every packet the same steps need to be followed which actually involves the cpu and lot of processing consequence diminish in performance.

Interrupt Context Switching
This is also switching technique used by many cisco routers and ios. According to interrupt context switching a cache is maintained which stores the information of packet which comes first. After that if it finds the same packet credentials then instead of going to the processor it will go to the cache. From cache it gets it all the requirements and forwards the packet towards the destination. That’s why it is called fast switching; optimum switching and cef switching all are using interrupt context switching.
Difference between process and interrupt context switching
1) A cache is maintained in the interrupt context switching where as in process switching it follows all the steps mention above.
2) Interrupt context switching is faster that process switching.
3) Interrupt context switching uses destination based load balancing whereas process switching uses per packet based load balancing.

shivlu jain

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