Xerox NS-2260 Port Sniffer Function, STP related parameters, Spanning tree port states

To provide path redundancy, Spanning-Tree Protocol defines a tree that spans all switches in an extended network. Spanning-Tree Protocol forces

certain redundant data paths into a standby (blocked) state. If one network segment in the Spanning-Tree Protocol becomes unreachable, or if

Spanning-Tree Protocol costs change, the spanning-tree algorithm re-configures the spanning-tree topology and reestablishes the link by activating the standby path.

Spanning-Tree Protocol operation is transparent to end stations, which are unaware whether they are connected to a single LAN segment or a switched LAN of multiple segments.

STP related parameters

Priority : A value to identify the root bridge. The bridge with the lowest value has the highest priority and is selected as the root.

MAC Address : The MAC address of the switch as a unique identifier to the network.

Max Age : The number of seconds a bridge waits without receiving Spanning Tree protocol configuration messages before attempting a reconfiguration. Maximum Age Timer measures the age of the received protocol information recorded for a port and ensures that this information is discarded when its age limit exceeds the value of the maximum age parameter recorded by the switch. The time -out value for this timer is the maximum age parameter of the switches.

Hello Time : The number of seconds between the transmission of Spanning Tree protocol configuration messages. It determines how often the switch broadcasts its hello message to other switches.

Forward Delay Time : The number of seconds a port waits before changing from its Spanning Tree Protocol learning and listening states to the forwarding state. Forward Delay Timer Monitors the time spent by a port in the learning and listening states. The time -out value is the forward delay parameter of

Spanning tree port states

Listening : Switches send messages to one another to establish the network topology and the optimal paths to the different segments of the network. Other data is not transmitted.

Blocking : The switch enters the Blocking State if a path with higher priority is found to exist during the Listening State. Normal data is not transmitted.

Learning : The switch enters the Learning State if no path with a higher priority is found during the Listening State. Learned entries are entered in the Unicast Destination Forwarding Table. Normal data is not transmitted.

Forwarding : The switch enters the Forwarding State after having been in the Learning State for a predefined time period. Normal data is transmitted.

Per port control settings

PathCost : Specifies the path cost for each port. The Spanning-Tree Protocol uses port path costs to determine which port to select as a forwarding port. You should assign lower numbers to ports attached to faster media (such as full duplex), and higher numbers to ports attached to slower media. The possible range is 1 to 65535. The recommended path cost is 1000 divided by LAN speed in megabits per second.

Priority : Specify STP port priority for each port. The port (physical or logical) with the lowest priority value has the highest priority and forwards the spanning-tree frames. The possible priority range is 0 through 255 (decimal). The default is 128. If all ports have the same priority value, the lowest port number forwards the spanning -tree frames.

1.5.8 Port Sniffer Function

Port sniffer function is a method to duplicate all traffic occurred on the specified monitored ports to the designated sniffer port. The traffic can be configured for incoming packets only or outgoing packets only or both. The control settings are:

Sniffer Mode : Specify the traffic type for monitoring