User`s manual

TN-5516/5518 Series Featured Functions
3-32
“Current Status” Items
Now Active
Shows which communication protocol is in use: Turbo Ring, Turbo Ring V2, RSTP, Turbo Chain or None.
“Settings” Items
Redundancy Protocol
Setting Description Factory Default
Turbo Ring This selects the Turbo Ring protocol.
Turbo Ring V2 This selects the Turbo Ring V2 protocol.
Turbo Chain This selects the Turbo Chain protocol.
RSTP (IEEE
802.1W/1D)
This selects the RSTP protocol.
None This disables ring redundancy.
None
Role
Setting Description Factory Default
Head Select this switch as the Head Switch
Member Select this switch as Member Switch
Tail Select this switch as Tail Switch
Member
Port Role
Setting Description
Head Port/Member
Port/Tail Port
This indicates the port role of the selected port number. For a Head Switch, it has a
Head port and a Member port. For a Member Switch, it has a 1st Member port and a
2nd Member port. For a Tail Switch, it has a Tail port and a Member port.
Port Num
Setting Description Factory Default
Port number Select any port of the switch to play the indicated port role. Port 1
Port Status
Setting Description
Forwarding This port is in forwarding state for normal transmission.
Blocked This port is the Tail port and is blocked as a backup path.
Link down The link connected to this port is broken.
The STP/RSTP Concept
Spanning Tree Protocol (STP) was designed to help reduce link failures in a network and provide protection
from loops. Networks that have a complicated architecture are prone to broadcast storms caused by
unintended loops in the network. The TN-5500’s STP feature is disabled by default. To be completely effective,
you must enable RSTP/STP on every TN-5500 connected to your network.
Rapid Spanning Tree Protocol (RSTP) implements the Spanning Tree Algorithm and Protocol defined by IEEE
Std 802.1w-2001. RSTP provides the following benefits:
• The topology of a bridged network will be determined much more quickly compared to STP.
• RSTP is backward compatible with STP, making it relatively easy to deploy. For example:
 It defaults to sending 802.1D style BPDUs if packets with this format are received.
 STP (802.1D) and RSTP (802.1w) can operate on different ports of the same TN-5500. This feature is
particularly helpful when TN-5500 ports connect to older equipment, such as legacy switches.
 Item 3.3
You get essentially the same functionality with RSTP and STP. To see how the two systems different, please
refer to Differences between RSTP and STP later in this chapter.