Q: Describe the following buffering mechanism in a reliable transport protocol i. Chained variable-sized buffers ii. One large circular buffer per connection

Note: see the attached picture and solve according to this.

Connection Establishment Host 1 Host 2 CR (seq = x) Normal operation: Host 1 sends CR containing a sequence number x Host 2 replies ACK to host 1 announcing its initial sequence no. y Host 1 acknowledges host 2s choice of initial sequence no. in the first data TPDU that it sends ACK (seq = y, ACK = x) DATA (seq = x, ACK = y) (a) Connection Establishment Host 1 Host 2 Old duplicate CR (seq = x) . . Old CONNECTION REQUEST appearing out of nowhere: This TPDU arrives at host 2 without host ls knowledge Host 2 reacts to this TPDU by sending host 1 an ACK When host 1 rejects host 2's attempt to establish a connection, host 2 realizes that it was tricked by delayed duplicate ACK (seq = y, ACK = x) REJECT (ACK = y) (b) Connection Establishment Host 1 Host 2 Duplicate CONNECTION REQUEST and duplicate ACK: CR (seq = x) Old duplicate ACK (seq = y, ACK = x) The worst case is when both a delayed CR and an ACK are floating around in the subnet DATA (seq = X ACK = z) Old duplicate REJECT (ACK = y) (c) Connection Release Two styles for terminating a connection 1. Asymmetric Release: When one party hangs up, the connection is broken. Telephone system 2. Symmetric Release: Treats connection as two separate unidirectional connections and requires each one to be released separately Connection Release Host 1 Host 2 CR ACK Asymmetric Release:. It is abrupt and may result data loss When the data is transferring from host 1 to host 2, host 2 issues a DR The result is that the connection is released and data are lost DATA DATA DR No data are delivered after a disconnect request