関連ワード:  what is the role of data link layer    what is the role of data link layer in osi model    what is the responsibilities of data link layer    what is the purpose of data link layer    what is the function of data link layer in osi model    what is the significance of data link layer    what is the purpose of data link layer in osi model    what is the importance of data link layer    what is the job of data link layer    what is the role of checksum in data link layer