Nortel Ethernet Switch 325-24G AL2012A46-E5 用户手册

3

Layer 2 features

VLAN support

Up to 255 port-based VLANs can be
established on an Ethernet Switch 325 to
extend the broadcast domain and segment
network traffic for higher network effi-
ciency. IEEE 802.1Q VLAN Trunking
is supported on every port of the switch,
allowing efficient means of transporting
broadcast domains. Additionally, the
Ethernet Switch 325 provides the ability
to have both tagged and untagged
frames on the same port for easy traffic
segmentation with minimal setup. 

Enterprise-sized MAC 

address table

The Ethernet Switch 325 models support
up to 8,000 MAC addresses, providing
ample scalability for growing networks
wishing to connect many devices and
workgroups to each switch.

IGMP snooping

The Ethernet Switch 325 models feature
IP Multicast support by examining
(‘snooping’) all Internet Group Multicast
Protocol (IGMP) traffic in hardware at
line rate, and filtering out multicast
streams not of interest to particular 
end-stations, thereby enabling peak
computer performance.

Spanning Tree Protocol

Built-in support for Spanning Tree
Protocol (IEEE 802.1D) detects and
eliminates logical loops in the network.
When multiple paths exist, the switch
will automatically place some ports on
standby to form a network with the
most efficient traffic pathways, avoiding
the continual looping of frames.

Rapid Spanning Tree Protocol

Rapid Spanning Tree Protocol (RSTP or
IEEE 802.1w) defines how to reduce
the recovery time after a network break-
down. It also maintains backward
compatibility with IEEE 802.1d which
was the Spanning Tree implementation
prior to RSTP. In certain configurations,
the recovery time of RSTP can be reduced
to one second. RSTP also reduces the
amount of flooding in the network by
enhancing the way Topology Change
Notification (TCN) packet is generated.

Multiple Spanning 

Tree Protocol

Multiple Spanning Tree Protocol (MSTP
or IEEE 802.1s) allows you to configure
multiple instances of RSTP on the same
switch. Each RSTP instance can include
one or more VLANs. 

Link Aggregation 

Control Protocol

Link Aggregation (LA) allows you to
create and manage a trunk group. You
can control and configure a trunk group
automatically through the use of the
Link Aggregation Control Protocol
(LACP). The LACP defined by the
IEEE 802.3ad standard allows a switch
to learn the presence and capabilities of

a remote switch by exchanging informa-
tion with the remote switch, before a
trunk group is formed. Either switch
can accept or reject the aggregation
request with the far end on a per-port
basis. A link that cannot join a trunk
group operates as an individual link.

802.3ad provides an industry-standard
method for bundling multiple links
together to form a single trunk between
two networking devices. Trunks that
conform to the 802.3ad standard are
Link Aggregation Groups (LAGs). The
maximum number of LACP-based
trunk groups on a switch (in either
standalone or stacked configuration) is
six with a maximum of four ports
allowed for each trunk group.

Multi-Link Trunking

Multi-Link Trunking (MLT) enables
grouping of links between an Ethernet
Switch 325 and another switch or a
server to provide greater bandwidth with
active redundant links (see Figure 4).
The Ethernet Switch 325 models support
up to six MLTs per switch with up to
four ports per MLT.

Figure 4. Multi-Link Trunking (MLT)