Solved: ios operating system order of packet flow

Oscar Quinonez · ‎02-23-2010

Is there a DETAILED packet processing flow chart for IOS (specially the ISR platform)?

Something like;

packet comes to input interface -->

decision branches (depending on processing modes, route, inspection processes, session, policy lookup, nat, buffering, etc) -->

packet goes out output interface--->

Lei Tian · ‎02-24-2010

Hi Oscar,

This is general process order for all IOS software based router; ISR is in that category. For routers like 7600s, ASRs and Catalyst switches, they might not follow same order, because those are hardware based devices. Totally different animal.

HTH,

Lei Tian

View solution in original post

Lei Tian · ‎02-23-2010

Hi Oscar,

You can check the book by Russ White "Inside Cisco IOS Software Architecture"; on page 65 it has order of operations in the switching path.

Just in case you donot have that book, I screenshot that page and attach here. Hope that is waht you are looking for.

HTH,

Lei Tian

Oscar Quinonez · ‎02-23-2010

Hi Lei Tian,

and thank you for the prompt, and very informational response.

I definately will put this book on my safari shelf. With that in mind, Are there any publications like this for the ISR platform? also detailing other features like voip? or would you say that this pretty much the general architecture for IOS and would be platform independent?

thank you much,

-Oscar

Lei Tian · ‎02-24-2010

Hi Oscar,

This is general process order for all IOS software based router; ISR is in that category. For routers like 7600s, ASRs and Catalyst switches, they might not follow same order, because those are hardware based devices. Totally different animal.

HTH,

Lei Tian