TEG1210P 10-Port Gigabit Intelligent PoE Switch User Guide
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forwarding rule, namely stripping off their tag headers so that they can be identified by
common devices.
The following lists 2 common port types for tagged VLANs:
z
Access Type:The forwarding rule for this type is to strip off the tag headers of all
frames that are to be forwarded. Generally, this type of ports only belongs to 1 VLAN and
is usually used to connect switches to terminal devices.
z
Trunk Type:The forwarding rule for this type of ports is not to change the tag
headers of frames that do not match the port’s PVIDs. Ports of this type can belong to
multiple VLANs to transmit frames to and receive frames from multiple VLANs. They are
usually used in inter-switch connection.
¾
STP
1. STP
STP (Spanning Tree Protocol) which is based on IEEE802.1d standard is used to
eliminate potential physical loop in data link layer in a LAN. Devices that run this protocol
exchange packets to discover potential loops in a network and optionally block some
ports to trim the looped network architecture into a loop-free, tree-shaped one. As a result,
packets are prevented from incrementing and endlessly repeating in a looped network
and devices’ abilities to handle packets are also prevented from degrading due to
repeatedly receiving the same packets.
STP includes two senses. In a narrow sense, it is the STP defined in IEEE802.1d, and in
a broad sense, it includes IEEE802.1d defined STP and all other STP enhancements
based on IEEE802.1d.
2. RSTP
RSTP
（
Rapid Spanning Tree Protocol
）
, completely compatible downwards with 802.1d
STP, mostly features a “faster convergence” function in addition to the avoiding loops and
redundant link functions that classic STP has. If all bridges in a LAN support RSTP and
the administrator have configured appropriately, it takes a quite short time to regenerate a
topology tree (classic STP needs about 50 seconds while RSTP needs a minimum of 1
second), once network topology changes. RSTP can switch to forwarding state fast
without depending on counter settings any more. RSTP bridge is very sensitive to other
