Ethereal-users: [Ethereal-users] Re: Tethereal Cisco port identifier - how do get the decimal nu
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 (?!?)
On Sun, 7 Nov 2004 09:57:03 -0600, Stef <stefmit@xxxxxxxxx> wrote:
> I have a question regarding what tethereal calls "port identifer" -
> how can I convert that into a "real" port number? Here is what I am
> talking about:
>
> # tethereal -V -i eth2 |grep 'Port identifier' --> gets me:
>
> Port identifier: 0x20cd
>
> Now - if I were to take the above "ad-literam", then 0x = HEX ==> port
> = (20CD) decimal = 8397, which is definitely wrong! ... thus my
> question ...
>
> TIA,
> Stef
>
> P.S. [OT] While capturing traffic as above, I stumbled across some
> other thing:
>
> # tethereal -Nm -i eth2 |grep 'Cisco'
>
> Cisco_17:04:ce -> Cisco_17:04:ce LOOP Reply
>
> looking further into it , I found that the above is tethereal
> interpretation of a the 0x9000 protocol (loopback), but I couldn't
> find anything telling me what is causing it to run on a switch - any
> ideas?
>
