trace ip

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Trace a packet to the specified destination address.

Syntax: trace ip dest-address [src-address]

dest-address	IP address or host name (DNS) of the destination system.
src-address	Specifies the IP address of the source interface

Description: The trace ip command generates 3 datagrams addressed to the destination with the time-to-live (TTL) timer set to 1. The first receiving router on the path to the destination reads the timer, discards the packets, and returns an ICMP message.

The trace ip command repeats this process, incrementing the TTL until:

• the datagram reaches the specified destination
  
  
• the TTL expires
  
  
• you interrupt the sequence.
  
  

Output from the trace ip command consists of a list of all the routers between this router and the destination router including the round trip time for each of the three datagrams sent to that router. The clock granularity is 17ms; any round trip taking less than 17ms will display as 0.000 ms. If a '*' displays instead of a round trip time, it indicates that the probe datagram timed-out. The timeout interval is 5 seconds.

The source IP address of the trace route IP packets can be optionally specified providing the ability to check for the reachability of a specific source IP address from the trace route destination.

Use the trace ip command to display the IP routes a packet will traverse to the specified destination.

Use the trace ip dest-address src-address command to specify a particular source address for reachability from the destination address.

Pressing the CTRL-C key sequence aborts the trace.

Factory Default: None.

Command Mode: Executive and privileged.

Example 1: The following is sample output from the trace ip command initiated at host name server-doc2 and tracing the hops to host name firewall:

router#trace ip firewall Send to firewall(10.1.1.40) 30 hops max, 40 byte packets 1 sw-gate (10.5.0.1) 0.000 ms 0.000 ms 0.000 ms 2 10.1.4.1 (10.1.4.1) 0.000 ms 0.000 ms 0.000 ms 3 firewall (10.1.1.40) 0.000 ms * 0.000 ms router#

Example 2: The following is sample output from the trace ip command initiated at host name server-doc2 and tracing the hops to host name firewall from the source address 10.10.10.1:

router#trace ip firewall 10.10.10.1 Send to firewall(10.1.1.40) from 10.10.10.1 30 hops max, 40 byte packets 1 sw-gate (10.5.0.1) 0.000 ms 0.000 ms 0.000 ms 2 10.1.4.1 (10.1.4.1) 0.000 ms 0.000 ms 0.000 ms 3 firewall (10.1.1.40) 0.000 ms * 0.000 ms router#

The following table describes the fields in the display:

Table 1-15. Fields Displayed by trace ip 

Field	Description
send to	The host name and IP address (in parenthesis) of the final destination of the trace. If a host name is not defined, the IP address displays in both fields.
from	The source IP address for this trace.
hops max	The maximum number of hops the trace will traverse in an attempt to reach the destination IP address. Hops max is currently hard coded for 30 hops.
byte packets	The number of bytes in the trace packet. Byte packets is currently hard coded for 40 bytes.

Related Commands: None

Copyright © 2004 Avici Systems Inc.
Avici® and TSR® is a registered trademark of Avici Systems Inc.
IPriori™, Composite Links™, SSR™, QSR, and NSR® are trademarks of Avici Systems Inc.

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    Last Updated: 05/10/04 at 16:34:20

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