3.1.1.1
Mesh Architecture for UDH, PDH, MDH
The large industrial plant network architecture involves the use of root switches that communicate the Integrated Control
System (ICS) virtual local area networks (VLANs) over Single Mode Fiber (SMF) trunks to edge switches. For redundancy,
two or more identical switches are cabled together, enabling them to act as one switch with the port capacity of the combined
switches. These cables are connected through special ports or plug sockets in the rear of the switches.
Note
Refer to NetworkST for Mark VIe Controls Application Guide (GEH-6840).
Redundant switch cabling offers the following advantages:
•
Built-in failover and recovery (failback) in the event one of the switches fails.
•
An unconfigured switch can be used to replace a failed switch in pair. It will automatically upload the running
configuration from the other switch in the group.
•
Enhanced network storm control protection
•
Network redundancy
•
Gigabyte uplink speeds (with SMF)
•
Enhanced Quality of Service (QoS) – ensures UDH (controller traffic) always has priority over PDH network traffic.
•
Cisco switches are 802.1x compliant.
The current large industrial plant network topology uses pairs of edge switches and pairs of root switches to achieve
redundancy. Devices with redundant communications (HMIs, controllers) have a network connection to each of the two
switches in the pair. For
(TMR) controllers, the R controller is connected to the first switch, and
the S and T controllers are connected to the second switch.
MODE
Cat alyst
3750
- X Ser ies
BLANK
MODULE
FN
SYST
CONSOLE
XPSSTAT
SPEED
DUPLX
S-PWR
MAST
STACK
Catalyst
3750
-X Ser ies
1
2
3
4
5
6
7
8
9
10
11
12
MODE
Cat alyst
3750
- X Ser ies
BLANK
MODULE
FN
SYST
CONSOLE
XPSSTAT
SPEED
DUPLX
S-PWR
MAST
STACK
Catalyst
3750
-X Ser ies
1
2
3
4
5
6
7
8
9
10
11
12
Root S witches
E dge S witches
S witch connector
cable located rear
Mark VIe HMIs,
Historians
Legend
Cat alyst
2960
-S Ser ies
25
26
27
28
M
G
M
T
B
A
S
E
T
CONSOLE
STCK
SPED
DPLX
STAT
MSTR
RPS
SYST
MODE
13
X
14
X
23
X
24
X
13 14 15 16 17 1819 20 21 22 23 24
1 2
3 4
5 6
7 8
9 10 11 12
1
X
2
X
11
X
12
X
Cat alyst
2960
-S Ser ies
25
26
27
28
M
G
M
T
B
A
S
E
T
CONSOLE
STCK
SPED
DPLX
STAT
MSTR
RPS
SYST
MODE
13
X
14
X
23
X
24
X
13 14 15 16 17 1819 20 21 22 23 24
1 2
3 4
5 6
7 8
9 10 11 12
1
X
2
X
11
X
12
X
Catalyst 2960-S Series
25
26
27
28
M
G
M
T
B
A
S
E
T
CONSOLE
STCK
SPED
DPLX
STAT
MSTR
RPS
SYST
MODE
13X
14X
23X
24X
13 14
15 16
17 18
19 20
21 22
23 24
1 2
3 4
5 6
7 8
9 10
11 12
1X
2X
11X
12X
Catalyst 2960-S Series
25
26
27
28
M
G
M
T
B
A
S
E
T
CONSOLE
STCK
SPED
DPLX
STAT
MSTR
RPS
SYST
MODE
13X
14X
23X
24X
13 14
15 16
17 18
19 20
21 22
23 24
1 2
3 4
5 6
7 8
9 10
11 12
1X
2X
11X
12X
E dge S witches
Mark V Ie
Controller
S et
Cat alyst
2960
- S Series
25
26
27
28
M
G
MT
B
AS
E
T
CONSOLE
STCK
SPED
DPLX
STAT
MSTR
RPS
SYST
MODE
13
X
14
X
23
X
24
X
13 1415 16 17 18 19 2021 22 23 24
1 2
3 4
5 6
7 8
9 10
11 12
1
X
2
X
11
X
12
X
Cat alyst
2960
- S Series
25
26
27
28
M
G
M
T
B
AS
E
T
CONSOLE
STCK
SPED
DPLX
STAT
MSTR
RPS
SYST
MODE
13
X
14
X
23
X
24
X
13 1415 16 17 18 19 2021 22 23 24
1 2
3 4
5 6
7 8
9 10
11 12
1
X
2
X
11
X
12
X
E dge S witches
Trunk provides all V LA Ns
Cable: S i ngle Mode Fiber
Plant Data Highway (PDH)
Cable: Cat5e
Unit Data Highway (UDH)
Cable: Cat5e
Monitoring Data Highway (MDH)
connects to an OSM or RSG
Cable: Cat5e
R
S
T
Mesh Root and Edges
The Root bridge switch is at the top of the network spanning tree. The edge switches (Ethernet connections) are then
connected below the root switch. The most important element to this spanning tree is the root bridge placement. It should be
the most centralized switch on the network (typically located in the control room). All data flow across the network is from
the perspective of this switch. Root switches are configured to provide the control system VLANs and other optional
networks over trunks to the edge switches.
Ethernet Networks
GEH-6721_Vol_I_BP System Guide 79
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