Ip Traceroute - 3Com 4007 Command Reference Manual

298 C 12: I
HAPTER NTERNET

ip traceRoute

Layer 2
Switching
Modules
Multilayer
Switching
Modules
P (IP)
ROTOCOL
Tracks a route from Multilayer Switching Module to a specified
destination using default 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 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 module receives a
indicates that the packet reached the host.
The probe exceeds the maximum number of hops (default
At each TTL setting, the module 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 (
probe. Other characters that can be displayed include the following:
— Network is unreachable
!N
— Host is unreachable
!H
— Protocol is unreachable
!P
— Fragmentation is needed
!F
— Unknown packet type
!<n>
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.
message, which
Port Unreachable
).
30
) for that
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