# MTP2

#### Error Control 

Checks the error in a received frame based on 16 bits CRC. Re-transmits lost message or error message.

#### Sequencing 

Maintains the sequencing of messages between directly connected nodes. Forward and backward sequencing numbers are maintained for sequence and re-transmissions.

#### Link Alignment 

Is link alignment based on the request from MTP3. 

#### Flow control 

If the receiver is slow, sending mtp2 gives an indication to its user for congestion. 

#### Link Status 

Link status is given to the user , the status may be, in service , out of service or congestion.