Thomas Kunz
Systems and Computer Engineering
379
Link Level Retransmissions
Issues
nHow many times to retransmit at the link level before giving up?
–Finite bound -- semi-reliable link layer
–No bound -- reliable link layer
nWhat triggers link level retransmissions?
–Link layer timeout mechanism
–Link level acks (negative acks, dupacks, …)
–Other mechanisms (e.g., Snoop, as discussed later)
nHow much time is required for a link layer retransmission?
–Small fraction of end-to-end TCP RTT
–Large fraction/multiple of end-to-end TCP RTT