Nortel Ethernet Switch 470-24T-PWR AL2012A53-E5 用户手册

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Unit Replacement Feature

In the unlikely event that a switch fails
in a stack, the affected switch can easily
be replaced without disrupting the
stack. This feature provides the capa-
bility of upgrading a new unit with the
configuration of the affected unit off-
line, before adding the new unit to the
stack. The configuration of the affected
switch may be copied from the Trivial
File Transfer Protocol (TFTP) server to
the new switch. The new switch can
then be inserted into the stack without
requiring a reboot of the entire stack. 

Distributed Multi-Link
Trunking

Multi-Link Trunking (MLT) enables
grouping of links between the Ethernet
Switch 470 and another switch or server
to provide greater bandwidth with active
redundant links. With Nortel’s Distrib-
uted Multi-Link Trunking (DMLT)
feature, trunked ports can span multiple
units of the stack for fail-safe connec-
tivity to mission-critical servers and the
network center (Figure 3). This can
provide greater bandwidth up to 8 Gbps
with active redundant links in one
trunk. Up to six trunks are supported
per switch or stack.

The resilient trunking features DMLT
and MLT of the Ethernet Switch 470
can be combined with the SMLT
feature of 8600, 8300, 5500 or 1600
switches in a cluster configuration
providing a self-healing network which
delivers maximum reliability and avail-
ability (Figure 4). Multiple connections
to the network core allow customers to
double their network bandwidth with
no extra investment as all ports are
active in SMLT configuration.

802.3ad Link Aggregation

IEEE 802.3ad provides an industry-
standard method for bundling multiple
links together to form a single trunk
between two networking devices. Both
Dynamic Link Aggregation Group
(LAG) trunks and MLT trunks are
supported. Once configured, the Link
Aggregation Group or trunk group is
managed by the Link Aggregation
Control Protocol (LACP). When one of
the active links goes down, the standby
link becomes active. 

Virtual Link Aggregation Control
Protocol (VLACP)

VLACP is a Nortel extension of the
Link Aggregation Control Protocol to
provide a Layer 2 handshaking protocol
which can detect end-to-end failure
between two physical Ethernet inter-
faces. It allows the switch to detect uni-
directional or bi-directional link failures
irrespective of intermediary devices and
enables significant improvements in
network fail-over times.

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.

Multiple Spanning Tree protocol
groups

The Ethernet Switch 470 supports
Nortel’s multiple spanning tree groups
(STGs). They support a maximum of
eight STGs, either all in one standalone
switch or across a stack. Multiple STGs
provide multiple data paths, which can be
used for load balancing and redundancy.

Rapid Spanning Tree Protocol 

Built-in support for Rapid Spanning
Tree Protocol (IEEE 802.1w) and
Multiple Spanning Tree Groups (IEEE
802.1s) provides standards-based solu-
tions for eliminating logical loops in the
network. 

Full Auto-sensing on Every Port

Every UTP port on the Ethernet Switch
470 is equipped with autosensing
technology to automatically detect and
support the speed and mode of a
connected device. The ports determine
whether a connected device is operating
at 10 Mbps or 100 Mbps, and automat-
ically adjust to the optimal speed. 

Figure 2. In the unlikely event of a

switch failure, the stack integrity is

maintained: cascade signals loop

back at point of failure.

Multi-Link Trunking
to Ethernet Switch 
at the network center

Multi-Gigabit

load-balancing and

failover protection

for uninterrupted

access to local

servers and the

network center

Figure 3. Distributed Multi-Link

Trunking across stack for higher

bandwidth and fault tolerance