What is MSS/MTU ?
Prerviously we have discussed TCP and UDP protocol and in that we are sending data . In this we will discuss the payload size so that we send our payload that is accepted by other network also.
MTU (Maximum Transmission Unit)
MTU represents the maximum size of a packet that can be transmitted over a specific network. It refers to the maximum payload size in bytes that can be carried in a single packet.
Whenever, the payload size exceeds the MTU of a network, the data will be fragmented into smaller packets to fit the MTU size.
MTU is a general network parameter and operates at the Network Layer (Layer 3) of the OSI model.
Lets see case ,
In this case, data is going from A->C .
but B->C support only 1200Bytes.
So ,we have to fragment data into smaller as 1500/2 =750 Bytes. Now packet size will be able to move from B->C and last we will also consolidate our data to 1500 Bytes again.
Here we have used ethernet cabl which allow only 1500 Bytes but LAN cable allow 9000Bytes.
Here we can see MTU clearly.
When we say MTU it also consists TCP/IP heeader which has headers.
Thier header consists of 20 Bytes -20 Bytes each.
MSS(Maximum segment size)
From above Diagram we can see when we remove 20 -20 Bytes of TCP/IP header then the memory we are left is called MSS i,e 1460 in ethernet cable.
MSS is specific to TCP so operates at the Transport Layer (Layer 4).
It takes into account the MTU of the network link and any additional protocol overhead. When TCP is used over IP networks, the MSS value is negotiated during the TCP handshake process.
Conclusion
Both MTU and MSS are important considerations for efficient and reliable data transmission over networks, ensuring that packets are appropriately sized to avoid fragmentation and optimize network performance.
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