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Difference Between MSS and MTU in Computer Networking

Last Updated : 20 Apr, 2023
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MSS and MTU are two types of important factors and aspects in computer networking that determine the size of each data packet or block to transmission service so that it can be transferred over the computer network as a complete single unit without any breakage. MSS stands for Maximum TCP Segment Size and it uses three-way handshaking that satisfies all the basic networking protocols. MTU stands for maximum transmission unit which decides the ability of the host machine in the computer network to transmit and receive large blocks of data and files all at once at a particular time. MSS is the more advanced and secure version of MTU.

MTU stands for maximum transmission unit. The data transmission that takes place in a network is responsible for calculating the largest data packet which is unique and can be transferred as a single distinct entity across the network during the transmission. It basically states that an increase in the ratio of the MTU during the transmission phase will result in a single and strong connection to the network which reduces the payload present on each data packet in the network transmission. MTU decides the ability of the host machine in the computer network to transmit and receive large blocks of data and files all at once at a particular time. It is responsible for deciding the ability of the computer to determine and compute the optimal and the most effective data size of the packets in the network.  

The formula for calculating the value of MTU is as follows:

MTU = MSS + 40 (IP header + TCP header)

MSS is a TCP header field of data bits that are used for indicating the device with the maximum amount of data capacity in it. MSS stands for Maximum TCP Segment Size. MSS follows the TCP/IP handshake which takes place using three-way handshaking that satisfies all the basic networking protocols. MSS is similar to the MTU, but instead, it is used with the help of TCP protocol using layer 4. Whenever a new device in the network remains connected to the server, then the three-way handshaking operation takes place by inserting their header payload file into the TCP header of the networking protocol. The MSS is the more advanced and secure version of MTU. It is responsible for deciding the factor by which the fragmentation of the segments present in the TCP header will take place at the transport and tunnel mode of the TCP/IP protocol.

The formula for calculating the value of MSS is as follows: 

MSS = MTU - 40 (IP header + TCP header)

Difference between MSS and MTU:

MSS MTU
MSS stands for Maximum TCP Segment Size.  MTU stands for maximum transmission unit protocol. 
MSS uses the three-way handshake protocol for the TCP header. MTU doesn’t use the handshaking protocol for the TCP header.
MSS doesn’t use the fragmentation of the data packets as compared to the lower value of MTU protocol. MSS uses the fragmentation of the data packets as compared to the lower value of MTU protocol.
It calculates and determines the amount of segmentation that occurs at each layer of transport and tunnel mode of TCP protocol. It doesn’t determine the amount of segmentation in each layer of TCP protocol.
It doesn’t have any ability for data transfer across the network router. It decides the ability of the network gateway for the maximum amount of data bytes that can be transferred from one router terminal to another.
It uses the layer-4 protocol for TCP/IP. It uses the layer-2 protocol for TCP/IP.
It determines the maximum size of the payload of data blocks for transmission. It determines the maximum data size to be transferred between two network routers.
MSS = MTU – 40 (IP header + TCP header) MTU = MSS + 40 (IP header + TCP header)
  MSS  MTU
Definition The maximum amount of data in a TCP segment that can be sent in a single packet without fragmentation. The largest amount of data that can be transmitted in a single packet on a network.
 
Protocol TCP (Transmission Control Protocol)  Network layer protocols such as IP (Internet Protocol)
 
Unit of Measure Bytes  Bytes
 
Calculation MSS is negotiated between the sender and receiver during the TCP handshake.  MTU is determined by the underlying network technology, and can be configured on network devices.
 
Fragmentation If a TCP segment is larger than the MSS, it is divided into smaller segments and sent separately.  If a packet is larger than the MTU, it is fragmented into smaller packets to be transmitted across the network, and then reassembled at the receiver.
 
Impact on Performance Fragmentation of large segments can result in increased overhead and reduced performance.  Fragmentation can result in additional processing overhead and increased network traffic, which can impact performance.
 
Importance MSS can impact the performance and reliability of TCP connections.  MTU can impact the performance and reliability of network connections, especially in environments where fragmentation is common.
 

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