3com S7906E 설치 설명서

 

1-4 

5)  Upon receiving the reply, the source device adds the IP address (1.1.1.1) of its inbound interface to 

the RR option. Finally, you can get the detailed information of routes from Device A to Device C: 

1.1.1.1 <-> {1.1.1.2; 1.1.2.1} <-> 1.1.2.2. 

By using the tracert command, you can trace the Layer 3 devices involved in delivering an IP packet 

from source to destination to check whether a network is available. This is useful for identification of 

failed node(s) in the event of network failure. 

Figure 1-2 Tracert diagram 

 

 

 

The tracert function is implemented through ICMP, as shown in 

: 

1)  The source (Device A) sends a packet with a TTL value of 1 to the destination (Device D). The UDP 

port of the packet is a port number that will not be used by any application of the destination. 

2)  The first hop (Device B) (the Layer 3 device that first receives the packet) responds by sending a 

TTL-expired ICMP error message to the source, with its IP address 1.1.1.2 encapsulated. In this 

way, the source device can get the address (1.1.1.2) of the first Layer 3 device. 

3)  The source device sends a packet with a TTL value of 2 to the destination device. 

4)  The second hop (Device C) responds with a TTL-expired ICMP error message, which gives the 

source device the address (1.1.2.2) of the second Layer 3 device. 

5)  The above process continues until the ultimate destination device is reached. No application of the 

destination uses this UDP port. Therefore, the destination replies a port unreachable ICMP error 

message with the destination IP address 1.1.3.2. 

6)  When the source device receives the port unreachable ICMP error message, it knows that the 

packet has reached the destination, and it can get the addresses of all the Layer 3 devices involved 

to get to the destination device (1.1.1.2, 1.1.2.2, 1.1.3.2). 

Follow these steps to configure tracert: 

Enter system view 

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