Principle of the H3C three layer switch

Principle of the H3C three layer switch            

The following respectively to JD379A price two network circumstances inter host communication to explain the principle of the three layer switch forwarding.

Network 1 as shown in Figure 12, a communication source, destination host is connected on the same layer three switches, but they are located at differentVLAN (network). For the three layer switch, the two hosts are located within itsdirectly connected network segment, the corresponding IP their routing aredirectly connected route.

Networking 1

Figure 12 marked MAC, IP address, gateway two hosts, and the three layer switch MAC, the different configurations of VLAN three layer interface IP.When PC A launched the ICMP request to the PC B, the process is as follows:(hypothesis three layer switch may not establish any hardware forwardingtable entries)

(1) according to the above description, PC A first to check out the destination IP address 2.1.1.2 (PC B) and they are not in the same segment, so itrequests the gateway address corresponding to the 1.1.1.1 MAC ARP requests;

(2) L3_SW received PC A ARP request, check the request message was the request IP is three layer interface IP on their own, thus sending ARP responseand the three layer interface (MAC S) MAC own contained therein. At the same time it will take the corresponding IP address and MAC address of PC A(1.1.1.2<==>MAC A) relationship of records to the ARP table own to (because the ARP request message contains the sender's IP and MAC);

(3) PC A gateway (L3_SW) ARP response, assembly of the ICMP requestmessage and send the message to the MAC = MAC, S, MAC = MAC A = 1.1.1.2, IP, buy HP JD375A source destination IP = 2.1.1.2;
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