Queuing and Drops

[ccannon88567]

Could somebody please explain what may cause an input queue on an interface to have drops?

If the interface that the packet needs to be switched to is busy does the interface put it into an Input queue or does it switch it to the busy interface which will in turn put it into an output queue?

Please help me to understand the queueing policies! :-)

Thanks.

[royalblues]

When a packet enters the router, the router attempts to forward it at interrupt level. If a match cannot be found in an appropriate cache table, the packet is queued in the input queue of the incoming interface to be processed.

Some packets are always processed, but with the appropriate configuration and in stable networks, the rate of processed packets must never congest the input queue. If the input queue is full, the packet is dropped.

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a0080094791.shtml

Narayan