Re: Draft-ietf-bridge-bridgemib-smiv2 Issues Resolution

The PortID used to identify a port in STP (or RSTP or MSTP...) is
16 bits.  Of that, the upper four bits is used for port priority,
and the lower 12 bits are used for the port number, which
effectively limits you to 4k ports per bridge. (This was where the
changes to port priority came from in .1t.  Originally the port
priority and port number were 8 bits each, which limited you to
256 ports per bridge.)  512 bytes can hold a bitmask representing
4k ports.

John

Juergen Schoenwaelder wrote:
> On Tue, Jan 11, 2005 at 04:17:28PM -0500, David B Harrington wrote:
> 
> 
>>3) the range has been constrained in the revision. This is probably
>>not a problem, but it is a semantic change.
> 
> 
> Does someone recall where the introduced size limit for ...AllowedToGoTo
> object comes from?  The port index is restricted to 65535 and from that
> perspective the upper boundary would be 8K and not 512 bytes (which 
> is equivalent to a maximum of 4096 ports). Can some IEEE 802.1 expert
> please explain this?
> 
> /js
>