What is the different between IP Fragmentation and TCP Segmentation?
A30. IP fragmentation occurs at Layer 3 (IP) and that 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 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, this allows the final receiver to reassemble the fragments into the original IP packet. Please see Resolve IP Fragmentation, MTU, MSS, and PMTUD Issues with GRE and IPSEC for more information. TCP Segmentation takes place when when an application on an end station is sending data. The application data is broken in
