Consider an institutional LAN shown in the figure below that

Consider an institutional LAN shown in the figure below, that is composed of five hosts (A, B, C, D, and E) and two transparent switches (Switch 1 and Switch 2). Assume that five frames are exchanged between the hosts as follows: A sends to B, D sends to E, E sends to C, E sends to A, and C sends to E. Show the detailed process and contents of the switch tables of each of the two switches in each step of the process.

Solution

In the starting mac table is empty for every switches so When host A wants to send data to host B connected to a same switch , first host A tries to ping the receiver(host B) host A creates a frame and uses ARP(address resolution protocol) request to broadcast the frame as the frame having ( source A ip and mac address and source B IP only ) the process is done to get the receiver\'s mac address so in this scenario host A will shout to every device at the other end as i m having the ip whoesever having the mac of this ip send and the arp reply by the receiver reply is unicast . as the connection made now the frame is to be transferred . ping uses ICMP echo , reply mechanism to communicate. This is done cause in the starting of the network switches mac table is empty so they doen\'t which mac is connected to which port by this mechanism only the mac table is found out by switches.

**one more thing switch learn the mac address by seeing the source mac address , in the above scenario the mac table gets updated with only host A mac and not with host B also, whosever will be the source got its mac addres uddated in the mac table.

the same condition goes how host D sends frame to host

IF the mac table is filled for switch then no need for this arp broadcast mechanism , directly the sender will send the frame to the receiver easily.

when host E communicating with host C two switches are present in between them and trunk link is generated. now host E will try to ping host C so the arp req is broadcasted via one switch to another the other switch opens the frame and checks the ip address of the receiver and sees whether the receiver is directly connected yes so it will easily provide the frame to hostC it sees the frame discloses is check the ip and sends it mac in arp unicast rephy mechanism now the data will get transferred.