3Com 3500 manual Ip t

182CHAPTER 5: OUT-OF-BAND MANAGEMENT

management ip Traces a route to a destination using the default traceRoute options. traceRoute

Valid Minimum Abbreviation

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9000

9400

3900

9300

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Important Considerations

■TraceRoute information includes all of the nodes in the network through which a packet passes to get from its origin to its destination. It uses the IP time-to-live (TTL) field in User Datagram Protocol (UDP) probe packets to elicit an Internet Control Message Protocol (ICMP) Time Exceeded message from each gateway to a host.

■To change the default traceRoute options, use the management ip

advancedTraceRoute command.

■You can either supply the host name or IP address as part of the command string, or you can supply the information at the prompt.

■When you specify a host name, the host name and its associated IP address must be configured on a network name server. Also, you must add the IP address on the name server to the list of name server addresses that are associated with the network domain name. See Chapter 16 for more information about ip dns commands.

■To track the route of an IP packet, traceRoute launches UDP probe packets with a small TTL value and then listens for an ICMP Time Exceeded reply from a gateway. Probes start with a small TTL of 1 and increase the value by 1 until one of the following events occurs:

■The system receives a Port Unreachable message, indicating that the packet reached the host.

■The probe exceeds the maximum number of hops (default 30).

■At each TTL setting, the system launches three UDP probe packets, and the traceRoute display shows a line with the TTL value, the address of the gateway, and the round-trip time of each probe. If a probe answers from different gateways, the traceRoute feature prints the address of each responding system. If no response occurs in the

3-second timeout interval, traceRoute displays an asterisk (*) for that probe.