Q1 Three routers (RA, RB and RC) in a network are connected by links with MTU of 2400 bytes in each link. A client, P, sends a request as IP datagram to a server Q as shown in Figure 2. The link from P to router RA has an MTU of 2100 bytes. Q is connected to RC in the Ethernet LAN. The length of the original IP datagram (including the header) is 12800 bytes. Suppose this datagram is stamped with the identification number (ID) 593 and there is no optional information in the header. P RA1 RA3 RA RA2 RC1 RB1 RC2 RC3 RC RB RB2 Q Figure Q2 (a) How many IP segments are created in P? (b) Show ALL the IP packets (with ID, flag and Fragment Offset) from P to Q. (c) How many IP segments are received in Q? (d) If no loss and resend is needed, show the size of ALL Ethernet frames and their IP Fragment Offset from RC3 to Q. (20%) Q2 An ISP granted a block of IPv4 addresses starting with 142.38.0.0/16. The ISP needs to distribute these addresses to three groups of companies as follows: Group A has 128 companies; each needs 30 host addresses. Group B has 128 companies; each needs 120 host addresses. Group C has 32 companies; each needs 500 host addresses. Design the sub-blocks and give the slash notation for each sub-block by showing the address blocks for the 1st , 2nd and the last companies in each group. Find out how many addresses are still available after these allocations. (20%) C C N 2 2 3 8 C o m p u t e r N e t w o r k i n g P . 2 A s s i g n m e n t - 2 1 6 / 1 7 A system contains a sender and a receiver. Each frame carries 2000 bits which Q3 composes of a sequence number and data bits. The distance between the sender and receiver is 4000 km and the propagation speed is 2 x 108 ms-1. The channel bandwidth is 500 kbps and is full-duplex. The overhead due to the header and trailer is ignored. A timer is started when a frame is entirely sent out and the time-out of a frame is 100ms. (a) Go-back-N ARQ protocol is used with the maximum allowable window size in the sender. 3-bit sequence number (starting at 0) is used. The receiver acknowledges immediately when an information frame is received completely. The processing delay on the both sides and the transmission of time of ACK and NAK are ignored. The source has 11 data frames to be sent. It is known that the 3th source frame is lost in its first transmission and its retransmission and all other frames are transmitted and received successfully. With aid of a timing diagram, evaluate the total time required to complete the data transmission (all frames are transmitted and acknowledged). (b) Repeat (a) with Selective Repeat ARQ protocol.