APPENDIX
C
FastHub Stacks
This appendix explains how connecting the hubs to each other plays a role in managing a
stack of FastHub 400 models. This appendix provides the following information:
•
•
•
Interconnecting and cascading hubs
Building a hub stack
Adding and removing hubs in a stack
Interconnecting and Cascading Hubs
You can interconnect hubs by connecting them via the stacking connectors on the rear panel
of the hubs. The interconnected hubs in the hub stack appear to the rest of the network and
to the management interface as a single logical repeater.
Interconnecting hubs differs from cascading hubs, which are connected via the standard
10/100 ports on the front of the hub. The connected hubs then appear to the rest of the
network and to the management interface as two logical repeaters.
Note The “Ethernet and FastHub Cabling Guidelines” section on page B-7 provides
additional information about repeater types and Ethernet network guidelines, including
determining acceptable cable distances between a FastHub 400 model, FastHub stacks, and
attached network devices.
FastHub Stacks C-1
Interconnecting and Cascading Hubs
Figure C-1 shows four interconnected hubs creating a logical repeater with a maximum of
96 ports in the stack and two cascading hubs creating two logical repeaters with a maximum
of 48 ports.
Figure C-1
Logical Repeater Configurations
Interconnected through the stacking
connectors and stacking cables
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
CONSOLE
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
MEDIA MODULE
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
MEDIA MODULE
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
MEDIA MODULE
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
MEDIA MODULE
1 logical repeater
10BaseT/100BaseTx
SYSTEM
10BaseT/100BaseTx
RPS
10 100
UTL 100
MODE
SYSTEM
1x
2x
3x
4x
5x
6x
7x
8x
9x
10x
11x
12x
13x
14x
15x
16x
17x
18x
19x
20x
21x
22x
23x
24x
RPS
24
10 100
1x
2x
3x
4x
5x
6x
7x
8x
9x
10x
11x
12x
13x
14x
15x
16x
17x
18x
19x
20x
21x
22x
23x
24x
24
UTL 100
MODE
2 logical repeaters
C-2
FastHub 400 10/100 Series Installation and Configuration Guide
14519
Cascaded through the 10/100 ports
Interconnecting and Cascading Hubs
You can use Class II repeaters to build networks with two or more repeaters or hub stacks
in a single collision domain. With two Class II repeaters, you can have a short cable
segment connecting the repeaters while maintaining 100-meter Category 5 connections to
the attached stations. Using more than two repeaters in a single collision domain requires
considerably shorter connections to attached stations. Figure C-2 shows the connection of
two hub stacks through the front-panel 10/100 ports to form a collision domain with up to
190 ports.
Figure C-2
Collision Domains
Cascaded through the front-panel 10/100 ports
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
CONSOLE
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
MEDIA MODULE
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
DC INPUT
DOWN
MEDIA MODULE
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
MEDIA MODULE
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
DOWN
MEDIA MODULE
UP
MEDIA MODULE
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
CONSOLE
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
MEDIA MODULE
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
UP
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DC INPUT
DOWN
DC INPUT
DOWN
MEDIA MODULE
Logical repeater 1
MEDIA MODULE
Logical repeater 2
Two repeaters in a single collision domain with up to 190 ports
10BaseT/100BaseTx
10BaseT/100BaseTx
RPS
10 100
SYSTEM
1x
2x
3x
4x
5x
6x
7x
8x
9x
10x
11x
UTL 100
12x
13x
14x
15x
16x
17x
18x
19x
20x
21x
22x
23x
24x
RPS
24
10 100
1x
2x
3x
4x
5x
6x
7x
8x
9x
10x
11x
12x
13x
14x
15x
16x
17x
18x
19x
20x
21x
22x
23x
24x
24
UTL 100
MODE
MODE
Logical repeater 1
Logical repeater 2
Cascaded through the 10/100 ports
Two repeaters in a single collision domain with up to 46 ports
14518
SYSTEM
FastHub Stacks C-3
Building a Hub Stack
Building a Hub Stack
You can interconnect up to four FastHub 400 models to build a hub stack by using the
stacking cables and the stacking connectors on the rear panel of the hubs. The stacking
cables can be ordered separately (model number WS-C400-CAB-EXP).
Note Do not install three or more FastHub 400M models in the stack, and do not
incorrectly stack the hubs. No electrical damage occurs; however, management functions
might not perform properly, and erroneous management information might be created.
Use the following guidelines when connecting the stacking cables:
•
•
•
•
•
A maximum of four FastHub 400 models can be interconnected into a stack. This
includes powered-down hubs in the stack.
A maximum of two FastHub 400M models can be in a stack. The upper management
hub is the primary management hub; the lower is the secondary management hub. For
more information, see the “Managing a Hub Stack” section on page C-6.
Never connect an UP connector to an UP connector or a DOWN connector to a DOWN
connector. Make sure you connect the UP connector of one hub to the DOWN connector
of the hub immediately above it. Similarly, make sure the DOWN connector of a hub is
connected to the UP connector of the hub immediately below it. See Figure C-3.
The hub at the top of the stack always has its UP connector open, and the hub at the
bottom of the stack always has its DOWN connector open.
Ensure that cable connector pins are lined up with stacking connector holes and that the
cable connector is aligned horizontally before slowly inserting the cable connector into
the stacking connector.
Caution Make sure the cable connector is properly aligned before inserting it into the
stacking connector. Inserting the connector at an angle damages the pins, making the cable
unusable.
C-4
FastHub 400 10/100 Series Installation and Configuration Guide
Adding and Removing Hubs in a Stack
Adding and Removing Hubs in a Stack
FastHub 400 models can be added to or removed from the hub stack without powering
down any hub in the stack. This is referred to as hot swapping. The stack reconfigures itself
in approximately 30 seconds. If you power down a hub in the middle of the stack and keep
it interconnected to the stack, the hubs above and below it continue to communicate.
Caution If you are removing a management hub and there is no secondary management
hub in the stack, you lose manageability for the entire hub stack. In addition, if the removed
management hub is mounted between two operating hubs, you split the Ethernet segment
into two separate segments when the stacking cables are disconnected.
Note Do not install three or more FastHub 400M models in the stack. No electrical
damage occurs; however, management functions might not perform properly, and
erroneous management information might be created.
Note If you keep a hub interconnected to the stack but only power down that hub, the hubs
above and below that powered-down hub will still communicate with each other. However,
you will not be able to manage that hub, and it will not be displayed from the hub manager.
Follow these steps to remove the hub:
Step 1
On the hub being removed, disconnect the stacking cable from either the DOWN
or UP connectors or from both connectors.
Step 2
Remove the hub from the rack or tabletop.
Note If you have a stack that has two management hubs and you remove one management
hub from the stack, it will have the same IP address as the stack. Avoid IP conflict by
changing the IP address of the removed management hub before you reuse it and connect
it to another hub stack in the network.
Note Removing hubs from the hub stack can introduce noise into the network through the
disconnected stacking cables. To prevent this, it is important that you either install a
replacement hub or reconnect the cables to existing hubs in the stack. See the “Building a
Hub Stack” section on page C-4 to interconnect the hubs.
FastHub Stacks C-5
Managing a Hub Stack
Managing a Hub Stack
You need at least one FastHub 400M model per three interconnected hubs (one hub stack)
if you want to manage the stack. A second FastHub 400M model in the stack can act as a
redundant stack manager in case the primary manager fails.
If a hub stack has more than one management hub, the upper management hub in the stack
is the primary management hub. The lower management hub is the secondary management
hub.
To manage the hub stack, you can use the system information (such as the IP, CDP, and
SNMP information) assigned to the primary management hub. The primary management
hub also stores the port settings of each hub in the stack. If the primary management hub
becomes inactive or is disconnected from the stack, the secondary management hub
becomes the primary management hub and uses the same stack information.
•
•
If a stack has only one management hub and another management hub is added to the
stack, the system information from the management hub that has the longest system-up
time is used by the topmost management hub. This happens if the new management hub
is added either above or below the preexisting management hub.
If you replace the only management hub in the stack with a different management hub,
the stack will use the settings of the newly installed management hub.
Caution If you are removing a management hub and there is no secondary management
hub in the stack, you lose manageability for the entire hub stack. In addition, if the removed
management hub is mounted between two operating hubs, you split the Ethernet segment
into two separate segments when the stacking cables are disconnected.
For information on managing the hub stack through the hub manager, see the “Managing
the Hub Segments” section on page 3-27.
C-6
FastHub 400 10/100 Series Installation and Configuration Guide
Numbering Convention of Hubs in a Stack
Numbering Convention of Hubs in a Stack
The physical position of the hubs in the hub stack and the stacking cable connections
between hubs determine how they appear to the management interface. The FastHub
management interface uses a hub-numbering convention, assigning numbers from top to
bottom—the hub at the top of the stack is Group 1, the hub below Group 1 is Group 2, and
so on (see Figure C-3). If you have four hubs in a stack and you remove Group 3 and
connect the stacking cable from Group 2 to Group 4, Group 4 is renumbered as Group 3.
If a hub stack has more than one management hub, the upper management hub in the stack
is the primary management hub. The lower management hub is the secondary management
hub. For more information, see the “Managing a Hub Stack” section on page C-6.
Figure C-3
Hub Stack Interconnection and Numbering Convention
Primary management hub
Group 1
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
CONSOLE
UP
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
DC INPUT
DOWN
MEDIA MODULE
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
CONSOLE
UP
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
DC INPUT
DOWN
MEDIA MODULE
UP
Group 4
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
DC INPUT
DOWN
MEDIA MODULE
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
UP
DC INPUTS FOR REMOTE
POWER SUPPLY
SPECIFIED IN MANUAL
+5V @6A, +12V @1A
DC INPUT
14520
RATING
100-127 / 200-240 V~
2A /1A 50 / 60 Hz
DOWN
MEDIA MODULE
Secondary management hub
FastHub Stacks C-7
Numbering Convention of Hubs in a Stack
C-8
FastHub 400 10/100 Series Installation and Configuration Guide