Problem
a) Consider a 1000 Mbps Ethernet with a single Store-N-Forward switch mid-way in the path between two nodes A and B. Assume that there are no other nodes on the network. Assume that the distance between the two nodes are 5 kilometres and the propagation speed of the signal in the medium is 2 x108m/s. Error detection at the switch gives an average delay of 1 microsecond per 100 bytes of frame data.(Assume all other delays to be negligible.)
i) What is the total transfer time (from the first bit sent by A to the last bit received by B) for an 1,200 byte frame?
ii) Same as (i) but consider that the Store-N-Forward switch now implements "cut-through" and is able to retransmit the frame as soon as the first 400 bits have been buffered.
b) The ASN.1 specification language is an integral part of the OSI Reference Model architecture, and is used in some protocols on the Internet. ASN.1 data objects are encoded for transmission using the Basic Encoding Rules (BER). Give an example of a transmitted byte-stream in hexadecimal by using the following module of data type declarations and its corresponding instances:
Volcano ::= OCTET STRING, year ::= INTEGER, Active ::= BOOLEAN
{Volcano, "Etna"}, {year, 2010}, {Active, 1}
c)
i) Give the structure of a typical Frame Relay frame and describe the role of each field in the frame.
ii) Explain the purpose of the DLCI field in the address segment of a Frame Relay frame. How big is this field usually?
iii) What is the purpose of the DSU/CSU in a Frame Relay network?