C4500

Cisco TAC

About the high CPU, Catalyst 4500 switch has 64 queues to carry packets from ASIC to software (CPU), however, only one queue is classified as high-priority queue, the rest 63 queues are normal priority queues. In other words, all these 63 queues are equal priority queues.

Only critical packets like BFD are put into high priority queue, all other protocol & data packets are put into one of the 63 queues.

Packets like EIGRP and OSPF protocol are put into 'L2 Router to CPU' queue. Both 'L2 Router to CPU' and 'L3 Receive' are of equal priority. They are different queues only because we do not want data packets to crowd-out protocol control packets.

The "L2 router to CPU, 7" queue is the queue belongs IPv4 link local range (224.0.0.x) including all Layer 3 protocol such as OSPF, HSRP, etc.