Magnum DS80 Dual-Speed Personal Hub Installation and User Guide (11/98)
GARRETT
9
2.3
Bridge logic between the 10 Mbps and 100Mbps Domains
Figure 2.4 : Internal view of
DS80 with bridge chip
Magnum D80’s
contain a bridge chip (Integrated Circuit) 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 10 Mbps , to communicate 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 DS80s to maintain high network performance. The bridge has 1.8K
node address capacity, suitable for use in medium-sized networks. Addresses are self-
learning so that filtering/forwarding of 10 Mbps and of 100Mbps packets is maintained
correctly even when users move their connection, or change speed, or power down.
2.4
Up-link Port 8X for Cascading
The unit has an up-link Port # 8X, located on the right-front side of the hub. It
enables the port’s cable to cascade to another shared hub or switching hub port. (See
Section 4.4 for more details about up-link). Like all DS80 ports, Port # 8X is a dual-
speed port which will sense the speed of the connected device. The up-link operates the
same, whether Port # 8X is connected to either 100Mbps or 10 Mbps devices.
When the up-link port is used to cascade two DS80 hubs, the auto-sensing
feature of the DS80 will cause the connecting link to operate at 100Mbps speed.
Bridge I.C
