What is the difference between IP fragmentation and TCP segmentation?
A. IP fragmentation occurs at Layer 3 (IP); TCP segmentation occurs at Layer 4 (TCP). IP fragmentation takes place when packets that are larger than the Maximum Transmission Unit (MTU) of an interface are sent out of this interface. These packets will have to be either fragmented or discarded when they are sent out the interface. If the Don’t Fragment (DF) bit is not set in the IP header of the packet, the packet will be fragmented. If the DF bit is set in the IP header of the packet, the packet is dropped and an ICMP error message indicating the next-hop MTU vlaue will be returned to the sender. All the fragments of an IP packet carry the same Ident in the IP header, which allows the final receiver to reassemble the fragments into the original IP packet. Refer to Resolve IP Fragmentation, MTU, MSS, and PMTUD Issues with GRE and IPsec for more information. TCP segmentation takes place when an application on an end station is sending data. The application data is broken into what TCP co
