F
EATURES
AND
S
PECIFICATIONS
R
EVISED
2018-09-21
O
VERVIEW
OF
A
DVANCED
F
EATURES
D
RAWING
N
O
. LP0991-G
1-4
N-Tron
®
Series NT24K
®
Software Manual
1.2.6
Rapid
Spanning
Tree
Protocol
(RSTP)
Rapid Spanning Tree Protocol as specified in IEEE 802.1D-2004, is supported. One Spanning Tree on one VLAN
is supported. (RSTP supersedes the Spanning Tree Protocol (STP) described in IEEE 802.1D-1998.) RSTP
establishes a simply connected active network topology from the arbitrarily connected bridges of a bridged
network. Bridges effectively connect just the LANs to which their forwarding ports are attached. Ports that are in a
blocking state do not forward frames. The bridges in the network exchange sufficient information to automatically
derive a spanning tree.
RSTP provides quicker learning of network topology changes than the older STP. RSTP supports new and
improved features such as the rapid transition of ports to the forwarding state. While STP transmits BPDUs (Bridge
Protocol Data Units) from only the root bridge, RSTP transmits BPDUs from every bridge. RSTP inter-operates
with older STP switches by falling back to STP when the older BPDUs are detected on bridge ports. The user can
also manually configure bridge ports to use STP, if desired.
1.2.7
SNMP
Traps
The NT24k Series switch supports SNMP Trap Stations to which SNMP Traps will be sent. Four standard SNMP
traps are supported: Link Status (Link Up / Link Down), Cold Start, Warm Start, and Authentication Errors. SNMP
Traps are sent to all trap stations configured on a given switch when the corresponding trap is enabled.
1.2.8
IGMP
Snooping
IGMP Snooping is enabled by default. The switch provides automatic (Plug and Play) IGMP configuration. IGMP
snooping provides intelligent network support for multicast applications, reducing unneeded network traffic. IGMP
Snooping is configured via the web console and if enabled, operates dynamically upon each power up. Also, there
can be manual only or manual and dynamic operation. Note that “static multicast group address” can be used
whether IGMP Snooping is enabled or not.
The Internet Group Management Protocol (IGMP) is a protocol that provides a way for a device to report its
multicast group membership to adjacent 'routers'. In this case NT24k switches provide router-like functionality.
Multicasting allows one computer to send content to multiple other computers that have identified themselves as
interested in receiving the originating computer's content. Multicasting can be used to transmit only to an audience
that has joined (and not left) a multicast group membership. IGMP version 2 is formally described in the Internet
Engineering Task Force (IETF) Request for Comments (RFC) 2236. IGMP version 1 is formally described in the
Internet Engineering Task Force (IETF) Request for Comments (RFC) 1112. The NT24k series supports v1 and v2.
IGMP Snooping will function dynamically without user intervention. If some of the devices in the LAN do not
understand IGMP, then manual settings are provided to accommodate them.
1.2.9
N
‐
Link™
The purpose of N-Link is to provide a way to redundantly couple an N-Ring topology to another topology, typically
another N-Ring topology. Each N-Link configuration requires 4 switches, two on each network. On the N-Ring
network, one switch is the N-Link Master and an adjacent switch is the N-Link Slave. On the connected network,
one switch is the N-Link Primary Coupler and another switch is the N-Link Standby Coupler.
N-Link monitors the link status of the Primary and Standby Coupler links. As long as the Primary Coupler link is
healthy, N-Link forwards network traffic and the Standby Coupler link blocks network traffic. When a problem is
detected on the Primary Coupler link, the Primary Coupler link blocks network traffic and the Standby Coupler
forwards network traffic. While the N-Link Master and Slave are in communication via the Control link, only one
Coupler link (Primary or Standby) forwards network traffic, while the other Coupler link blocks network traffic.
