> Ya you have answered my question:- "GVRP
> messages are sent among VLAN-aware devices to register their
> "membership". Can you please elaborate this senence. I mean is there a
> typical packet sent amoung the VLAN-aware devices. If yes then contents
> of the packet might be :
> Destination address : 01-80-C2-00-00-21,
> Source address : Address of the sender,
> TAG field : 4-byte.
> Fcs etc
> what are the contents of type/length and Data fields?
First of all, GVRP messages are never sent "tagged", as you indicate. (This
would be a circular-logic problem--receiving a tagged frame requires
membership in the VLAN identified by the tag, but you need GVRP to register
GVRP messages use Length encapsulation (not Type). After the Length is the
LLC-1 header, using DSAP=SSAP=0x42, and UI=0x03, the same as the Spanning
Tree Protocol. Following the LLC header, the BPDU protocol identifier is
0x01, to identify it as a GARP message, rather than 0x00 as used for
The attached pdf file is a page from my upcoming book that contains the
GVRP message format.
Rich Seifert Networks and Communications Consulting
(408) 395-5700 Los Gatos, CA 95033
(408) 395-1966 FAX
"... specialists in Local Area Networks and Data Communications systems"