The MAC layer protocol of
Ethernet can
create conflicts
on a network,
especially
when the network is
overloaded.
When there is a large
number of conflicts in an
industrial network, it will
lead to multiple data retransmissions,
thus increasing the uncertainty
of inter-network communication.
In industrial control networks,
this uncertainty of transmission from
one place to another can
degrade system control
performance.
X
Managed switches can support
QoS for real-time network
applications such as video
conferencing, IP phone,
and so on by having the
administrator designate the
priority of data transmission
according to the type of
data transmission. In a network
built with a common
switch, data cannot be adapted
to special network applications
such as multimedia, and must
be transmitted in order
regardless of the type.
X
Compared with ordinary
switches that do not
have network security features,
managed switches perform
better in securing data
storage and access, using
various methods such as VLANs,
PVLANs and ACLs to isolate
the networks of different
departments and deny access
to sensitive data by certain users.
In addition, with the help of access
lists,
it can also effectively stop
the spread of worm-type
viruses and restrict access
rights of certain
users to further protect
network security.
X
With technologies such
as Spanning Tree and
EtherChannel, managed switches
can redundantly
build
links and also multiply
the connection
bandwidth
between devices
(between switches, between switches and
routers,
between switches and servers),
while achieving network
load balancing to ensure
network stability.
If a redundant network is built
on a normal switch,
the network may be paralyzed
due to the presence of
topology rings. Without a
redundant network,
a part of the network,
or even the entire network,
may be disrupted when a line,
device, or module is
damaged.
X
|
Unmanaged
Switch
|
Managed
Switch
|
IP/MAC
|
X |
✓
|
Configuration |
X |
✓ (HTTP / HTTPS /
SNMP / Telnet / Cisco-Link CLI / RS232 Console)
|
Switching method |
Store-and-forward |
Store-and-forward |
Auto-negotiation |
✓
|
✓
|
Auto MDI/MDI-X |
✓
|
✓
|
Fault Relay |
✓
|
✓
|
Monitoring function |
X |
✓ (SNMP v1/v2/v3)
|
QoS (802.1p)
|
X |
✓
|
DHCP |
X |
✓
|
VLAN (802.1Q)
|
X |
✓
|
STP/RSTP (802.1D/802.1w)
|
X |
✓
|
IGMP |
X |
✓
|
X-Ring (recovery time<20ms) |
X |
✓
|