Wireshark · Ethereal-users: Re: [Ethereal-users] Re: Tethereal Cisco port identifier - how do get the decimal number? ... and so

[Stef <stefmit@xxxxxxxxx>]

Thanks, but ... comments in line

On Mon, 8 Nov 2004 03:00:59 +0100, Joerg Mayer <jmayer@xxxxxxxxx> wrote:
> On Sun, Nov 07, 2004 at 12:10:21PM -0600, Stef wrote:
> 
> 
> > Replying to my own post: digging further, I have found the
> > specification for STP calling for port ID in the format 0x80YY, where
> > YY is the HEX number for the port ID on the switch (at least this is
> > my understanding). So - in my case I should only look at the last two
> > "digits" (actually hex numbers), directing to a port number like:
> >
> > "CD" in hex = 205 in dec. ==> port number being 205 (?!?).
> >
> > I have tried to make sense of the above, assuming that the numbers are
> > counted from the beginning of a set of modules (e.g. for a chassis
> > with multi-port multiple modules), but still cannot come up with the
> > proper explanation. For example, in my case this traffic is caused by
> > port 37 on module 4 (4/37), with 2 previous modules (first is the SUP,
> > thus module 4 for the one I am investigating) with 48 ports each ==>
> > 205 - (2 * 48) = 205 - 96 = port 109 (?!?)
> 
> With STP, there are two ways to interpres the port identifier:
> - 8 bit priority + 8 bit port number (the old way of doing this)

This is what I assumed. No go, as you probably have already noticed
(CD=205 - no such port pn a switch). Or perhaps the Cisco port
numbering has nothing to do with the decimal equivalent of the last
8bit entry of the port ID?!?

> - 4 bit priority + 12 bit port number (the 802.1t aka new way of doing it)
> 
>  Ciao
>   Joerg
> 
> --
> Joerg Mayer                                           <jmayer@xxxxxxxxx>
> We are stuck with technology when what we really want is just stuff that
> works. Some say that should read Microsoft instead of technology.