3Com 3500 - page 478

478 CHAPTER 16: INTERNET PROTOCOL (IP)
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ip traceRoute For CoreBuilder 9000: Applies to Layer 3 switching modules only.
Traces a route to a destination using the default traceRoute options.
Valid Minimum Abbreviation
ip t
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 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 ip
advancedTraceRoute. (The co mmand description for “ip
advancedTraceRoute” lists the default traceRoute options.)
■You can either supply the host name or IP address as part of the
command string, or you can supply the infor mation at the prompt.
■When you specify a host name, the host nam e 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 “ip
dns domainName” earlier in this chapter for more information.
■To track the route of an IP packet, traceRoute launches User Datagram
Protocol (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, which indicates
that the packet reached the host.
■The probe exceeds the maximum number of hops (default 30).