After H1 of all data will be sent to every port in the form of broadcast, assume that the hub only 0/1 0/0/0, 0/two ports in use, as the s1 and A direct-connect
1 on two terminal IP, mask calculation, found that A, B in the same network segment, but did not establish the arp table, then send an arp request to the S1, the request content is "I know B IP, but I don't know MAC" B, B response back "I is B, my IP is XXX, my MAC is XXX", as A, B get IP - MAC table, table S1 and at the same time establish A MAC - port,
2 encapsulated into a frame, contains the source IP address, MAC source address, destination IP address, the destination MAC address and data blocks, sent to S1,
3 S1 published in MAC to find MAC corresponding port, port 0/0/3, the package sent to the device B,
4 B received packets,

CodePudding user response:

Pull to the IP is the three layers

CodePudding user response:

Switches learn all interface message source MAC, table maintenance on this table, forward according to the message destination MAC to check the table, if you have any address table, which also has the interface,

CodePudding user response:

According to the topology, you already not 2 switching questions,
S1 is supposed to be a router? That usually S1 in this position is to use routing, the A, B is not in A network segment, so is the routing problem,
If S1, 2, 3 mouth only enable the bridge function, the S1 in this problem is equivalent to a pure exchange, the process of the problem are as follows:
Assume that network is in the initial state, and launched by A first initial communications:
A may according to the target IP and its own IP and subnet mask, found that B and A network segment, query the native ARP cache to find B, then A ARP query, after after H1 and S1 forwarding to B, B found that the ARP request and their related (IP query target and their match), and ARP reply, also after S1 and H1 served A, then A knew B MAC, initiated in response to A B ARP query, remember is automatically learn A IP - MAC relationship (this is not very sure, can analyse, actually caught),
A and B are each other's IP - MAC after corresponding relation, IP communication can be established,

2 switching mainly study the ARP protocol, understand actually very simple,