Ethereal-users: Re: [Ethereal-users] Re: Tethereal Cisco port identifier - how do get the decima
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)
- 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.
