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Different TTLs when pinging devices.
- Thread starter raffski
- Start date
I just ran into the same issue. What I've been able to find out is that TTL's are specific to a manufacturer. With only limited experience here is the information I've been able to gather:
Older Microsoft devices use an initial setting of 32.
Newer Microsoft devices use an initial setting of 128.
HP Jetdirect cards use an initial setting of 60.
Ascend Pipeline router use an initial setting of 255.
BSD devices also use an initial setting of 255.
It appears to be completely arbitrary. However, it can be useful when trying to identify unknown devices.
Hope this helps.
Older Microsoft devices use an initial setting of 32.
Newer Microsoft devices use an initial setting of 128.
HP Jetdirect cards use an initial setting of 60.
Ascend Pipeline router use an initial setting of 255.
BSD devices also use an initial setting of 255.
It appears to be completely arbitrary. However, it can be useful when trying to identify unknown devices.
Hope this helps.
Also, ICMP is the bottom of the heap for getting the processors attention. If the CPU is busy with other things, ICMP waits or times out.
MikeS
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MikeS
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"The trouble with giving up civil rights is that you never get them back"
Due to bugs in the IP implementation of various hosts and switches, the IP trace command may behave in unexpected ways.
Not all destinations respond correctly to a probe message by sending back an "ICMP port unreachable" message. A long sequence of TTL levels with only asterisks, terminating only when the maximum TTL is reached, may indicate this problem.
There is a known problem with the way some hosts handle an "ICMP TTL exceeded" message. Some hosts generate in ICMP message, but they reuse the TTL of the incoming packet. Since this is zero, the ICMP packets do not make it back. When you trace the path to such a host, you may see a set of TTL values with asterisks (*). Eventually, the TTL gets high enough that the "ICMP" message can get back. For example, if the host is 6 hops away, traceroute times out in responses 6 through 11.
taken from the Cisco website
-Jeff ----------------------------------------
Wassabi Pop Tarts! Write Kellogs today!
Not all destinations respond correctly to a probe message by sending back an "ICMP port unreachable" message. A long sequence of TTL levels with only asterisks, terminating only when the maximum TTL is reached, may indicate this problem.
There is a known problem with the way some hosts handle an "ICMP TTL exceeded" message. Some hosts generate in ICMP message, but they reuse the TTL of the incoming packet. Since this is zero, the ICMP packets do not make it back. When you trace the path to such a host, you may see a set of TTL values with asterisks (*). Eventually, the TTL gets high enough that the "ICMP" message can get back. For example, if the host is 6 hops away, traceroute times out in responses 6 through 11.
taken from the Cisco website
-Jeff ----------------------------------------
Wassabi Pop Tarts! Write Kellogs today!
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