09-05-2004 02:33 AM - edited 03-02-2019 06:15 PM
Please explain the following traceroute:
Northhills-Router#trace titan
Translating "titan"...domain server (170.87.50.7) [OK]
Type escape sequence to abort.
Tracing the route to titan.umcaz.edu (170.87.50.2)
1 170.87.82.105 4 msec
170.87.82.133 4 msec
170.87.82.105 0 msec
2 170.87.81.25 4 msec
msfc-170-87-81-41.umcaz.edu (170.87.81.41) 4 msec
170.87.81.25 4 msec
3 titan.umcaz.edu (170.87.50.2) 0 msec 4 msec 4 msec
82.105 and 82.133 are two next hop routers to the same destination.
Thank You
Tom
09-05-2004 07:00 AM
The results of the traceroute are the result of default behaviors of the IOS. There are several basics to review and then the explanation should make sense.
- in Cisco's implementation of traceroute the router generates three probe packets at each time to live, and then increments the time to live and generates three probe packets, continuing this process till it finds the destination.
- Cisco put a sequence number in the display every time the TTL increases. So we can keep track of where it changes.
- Within a sequence if there are several responses from the same router they are displayed on the same line. If responses are received from different routers they are listed on separate lines.
- by default any packets generated by the router will be load balanced packet by packet if there are multiple routes to the destination.
So the explanation of your traceroute.
- sequence 1
- packet 1 with TTL 1 forwarded to 82.105 which responded TTL exceeded.
- packet 2 with TTL 1 forwarded to 82.133 which responded TTL exceeded.
- packet 3 forwarded to 82.105 which responded TTL exceeded.
- sequence 2
- packet 4 forwarded to 82.133 which forwarded toward the destination with next hop 81.25 which responded TTL exceeded.
- packet 5 forwarde to 82.105 which forwarded toward the destination with next hop 81.41 which responded TTL exceeded.
-packet 6 forwarded to 82.133 which forwarded toward the destination with next hop 81.25 which responded TTL exceeded.
- sequence 3
- packets 7, 8, and 9 with TTL of 3 all reached the target 50.2 which responded and the trace is over.
HTH
Rick
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