Black Box Dual-Speed Stackable Hubs Installation and User Guide
8
2.4
Bridge Module between the 10Mbps and 100Mbps
Domains
Figure 2.4 : Internal view of
LH8000A-M with bridge
module installed
An
LH8000A-M
contains a factory-installed bridge module to interconnect the two traffic domains, filtering and
selectively forwarding packets to allow only necessary packets to cross between the domains.
This enables all of the users and nodes connected into either domain, whether 100Mbps or
10Mbps , to talk to each other, and it keeps local traffic on one domain from consuming any of
the bandwidth of the other domain.
The bridge operates in the store-and-forward mode, which filters out bad packets and
maintains optimum performance in both domains. Packet forwarding delay is only 5
μ
s (plus
packet time), much less than traditional store-and-forward bridge products, enabling the
LH8000As to maintain high network performance. The bridge has 8K node address capacity,
suitable for use in large networks. Addresses are self-learning so that filtering / forwarding of
10Mb and of 100Mb packets is maintained correctly even when users move their connection, or
change speed, or power down.
The LH8000A-M’s bridge module is implemented as a daughter board. LH8000A
units have an LED on the front labeled ‘BR’ that will be ‘ON’ when the module is installed
internally. Power any LH8000A unit up and if the BR LED is ON, it is an LH8000A-M unit.
NOTE : Only one LH8000A-M (with a bridge module built-in) is allowed per
repeater stack. Thus, if the LH8000As in a stack have more than one BR
(bridge) LED ‘ON’, it is an illegal configuration.
2.5 Up-link Switch on Port 8 for Cascading
The unit has an up-link switch for Port # 8, located on the right-front side of the hub.
It enables the port’s cable to either connect to a user station ( = position) or to be cascaded to
another hub (X position). (See Section 4.4 for more details about up-link). Like all LH8000A
ports, Port # 8 is a dual-speed port which will sense the speed of the connected device. The up-
link switch operates the same, whether Port # 8 is connected to either 100Mbps or 10Mbps
devices. When the up-link port is used to cascade two LH8000A hubs or stacks together, the
auto-sensing feature will cause the connecting link to operate at 100Mb speed.
2.6 Features and Benefits
Bridge Module
