Question

with explanation please

Answer the following: 140.24.7.0/26 170.14.0.0/16 140.24.7.5 170.14.5.165 180.55.0.0/16 140.24.7.64/26 m1 m3 140.24.7.78 R1 mo R2 180.55.100.30 m2 180.55.60.14 mo m3 145.80.7.11 190.220.44.67 140.24.7.128/26 140.24.7.130 145.80.0.0/16 Rest of Internet a) Find the routing table for router R1. Mask Network Address Next hop Interface b) Find the routing table for router R2. Mask Network Address | Next hop Interface c) A packet arrives at router R1 with destination address 145.80.14.26. Show how it is forwarded. d) A packet arrives at router R2 with destination address 145.80.14.26. Show how it is forwarded.

Answer 1

Network Mask :-- When all Network ID bits become "1" then resultant IP is called it's Network Mask.

Ex : --    Network ID =>140.24.7.0/26 = _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ . _ _ 0 0 0 0 0 0 then all blank bits is Network ID(140.24.7.0/26) then, fill all with 1's to find Network Mask.

Network Mask = 1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 . 1 1 0 0 0 0 0 0 = 255.255.255.192

Next Hop :-- for any network it is the IP from which it receive / sent data packet from / to router

Interface :-- It is nothing but route of router from which we transmit data.

(a)

Mask	Network Address	Next Hop	Interface
255.255.255.192	140.24.7.0/26	140.24.7.5	m1
255.255.255.192	140.24.7.64/26	140.24.7.78	m3
255.255.255.192	140.24.7.128/26	140.24.7.130	m0
255.255.0.0	180.55.0.0/16	180.55.100.30	m2
255.255.0.0	170.14.0.0/16	180.55.60.14	m2
255.255.0.0	145.80.0.0/16	180.55.60.14	m2
255.255.255.255	Rest of internet	190.220.44.67	m2

(b)

Mask	Network Address	Next Hop	Interface
255.255.0.0	170.14.0.0/16	170.14.5.165	m1
255.255.0.0	145.80.0.0/16	145.80.7.11	m2
255.255.0.0	180.55.0.0/16	180.55.60.14	m0
255.255.255.255	Rest of internet	190.220.44.67	m3
255.255.255.192	140.24.7.64/26	180.55.100.30	m0
255.255.255.192	140.24.7.128/16	180.55.100.30	m0
255.255.255.192	140.24.7.0/26	180.55.100.30	m0

(c) When a packet arrives at router R1 with Destination Address 145.80.14.26 ,then it check in routing table and by seeing in it .The packet will go from interface m2 having IPAddress 180.55.100.30 which is next hop of router R2 having interface m₀ with IPAddress 180.55.60.14 . Then, packet arrives at router R2 with Destination Address 145.80.14.26.

By checking in routing table (checking Network ID) it go from interface m₂ having Network  Address and reach their desire pc.

(d) When a packet arrives at router R2 with Destination Address 145.80.14.26 ,then it check in routing table and by seeing in it (checking Network ID). The packet will go from interface m₂ having Network  Address and reach their desire pc.