Siemens S223 - Manual (Page 204)

UMN:CLI User Manual
SURPASS hiD 6615 S223/S323 R1.5
204 A50010-Y3-C150-2-7619
Port States
Each port on a switch can be in one of five states.
Blocking
Listening
Learning
Forwarding
BPDUs or timeout indicate
Potential to become active
BPDUs indicate port
should not be active
Forwarding timer
expired
BPDUs indicate port
should not be active
BPDUs indicate port
should not be active
Forwarding timer
expired
Disabled
Fig. 8.13 Port State
• Blocking
a port that is enabled, but that is neither a Designated port nor a Root port, will be in
the blocking state. A blocking port will not receive or forward data frames, nor will it
transmit BPDUs, but instead it will listen for other’s BPDUs to determine if and when
the port should consider becoming active in the spanning tree.
• Listening
the port is still not forwarding data traffic, but is listening to BPDUs in order to
compute the spanning tree. The port is comparing its own information (path cost,
Bridge Identifier, Port Identifier) with information received from other candidates and
deciding which is best suited for inclusion in the spanning tree.
• Learning
the port is preparing to forward data traffic. The port waits for a period of time to build
its MAC address table before actually forwarding data traffic. This time is the
forwarding delay.
• Forwarding
After some time learning address, it is allowed to forward data frame. This is the
steady state for a switch port in the active spanning tree.
• Disabled
When disabled, a port will neither receive nor transmit data or BPDUs. A port is in this
state because it is broken or disabled by administrator.