PLANET XGS3-24040 - Manual (Page 207)

13-73
13.1.21 spanning-tree format
Command:
spanning-tree format {standard | privacy | auto}
no spanning-tree format
Function:
Configure the format of the port packet so to be interactive with products of other companies. The
no command restores the default format.
Parameter:
standard：The packet format provided by IEEE
privacy：Privacy packet format, which is compatible with CISCO equipments.
auto：Auto identified packet format, which is determined by checking the format of the received
packets.
Default:
Auto Packet Format.
Command Mode:
Port Mode
Usage Guide:
As the CISCO has adopted the packet format different with the one provided by IEEE, while many
companies also adopted the CISCO format to be CISCO compatible, we have to provide support to
both formats. The standard format is originally the one provided by IEEE, and the privacy packet
format is CISCO compatible. In case we are not sure about which the packet format is on partner,
the AUTO configuration will be preferred so to identify the format by the packets they sent. The
AUTO packet format is set by default in the concern of better compatibility with previous products
and the leading companies. The packet format will be privacy format before receiving the partner
packet when configured to AUTO.
When the format is not AUTO and the received packet format from the partner does not match the
configured format, we set the state of the port which receives the unmatched packet to
DISCARDING to prevent both sides consider themselves the root which leads to circuits.
When the AUTO format is set, and over one equipment which is not compatible with each other are
connected on the port (e.g. a equipment running through a HUB or Transparent Transmission
BPDU is connected with several equipments running MSTP), the format alter counts will be
recorded and the port will be disabled at certain count threshold. The port can only be re-enabled by
the administrator.
Example:
Configure port message format as the message format of IEEE.
Switch(config)#interface ethernet 1/2
Switch(Config-If-Ethernet1/2)#spanning-tree format standard
Switch(Config-If-Ethernet1/2)#