The range of TTL values is dependent upon the size of the field reserved to
hold it. In many cases, devices that modify the field as the packet passes
through it decrement the value by one. Due to congestion and other facts of
network life, it's therefore quite easy for the value to become out of sync
with an interpretation of the TTL as a value corresponding to tranmission
time measured in seconds, and probably better corresponds to a hop count.
----- Original Message -----
From: "[EMAIL PROTECTED] (Timothy Ouellette)"
To:
Sent: Thursday, April 11, 2002 2:58 AM
Subject: Re: Ping times? Am i missing something [7:41151]
> Okay, so ICMP doens't specify a TTL on it's own. Doesn't IP by itself
> have a TTL of 255?
>
> Maybe i'm missing something.
>
> Tim
>
> On 11 Apr 2002 01:26:56 -0400, [EMAIL PROTECTED] ("Joseph
> Ezerski") wrote:
>
> >Ok, according to Stevens (TCP/IP Illustrated Vol 1), the ICMP Ping Packet
> >looks like this:
> >
> >
> > 0 1 2 3
> > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> > | Type | Code | Checksum |
> > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> > | Identifier | Sequence Number |
> > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> > | Optional Data |
> > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >
> >The RFC 792, does not specify a time value, other than IP TTL (at that
time,
> >assumed to be in units of seconds). I think it really depends on how
your
> >OS has implemented it. For example, on my Windows PC, the default
timeout
> >is 2000ms. However, there is an option you can set (-w in the windows
> >world) to extend that timeout. Stevens mentions something about newer
UNIX
> >implementations (as of the early 90s) timing out after 20 seconds. My
> >Solaris box times out after 20 s, and it is listed in the man pages as
such.
> >
> >HTH
> >
> >-Joe
> >
> >
> >
> >-----Original Message-----
> >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
> >Ouellette, Tim
> >Sent: Wednesday, April 10, 2002 8:13 PM
> >To: '[EMAIL PROTECTED]'; '[EMAIL PROTECTED]'
> >Subject: Ping times? Am i missing something
> >
> >
> >The other day while troubleshooting an issue, I saw some pings from out
> >Tivoli Netview box and it was showing ping times in the 15,000+ ms range.
Is
> >this possible? I though there was a limit on this particular field in the
> >head. If an of our frame-format experts (Priscilla?) or sniffer gurus
> >(again... Priscilla?), could point me someone I'd appreciate it. Thanks
a
> >bunch!
> >_________________________________________________________________
> >Commercial lab list: http://www.groupstudy.com/list/commercial.html
> >Please discuss commercial lab solutions on this list.
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