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Chapter 2 — Connecting to the Network
One of the most common reasons for a loss of network services is
damage to, or failure of, cabling interconnections. By taking
advantage of the “Auto-sense” (The AsantéBridge 1012 automati-
cally senses the presence of physical links connected to the 3in1
Uplink port), redundant network backbone links may be easily
configured for increased network reliability.
For example, thin Ethernet (BNC) wiring could be used as a
backup to a twisted-pair (10BaseT) backbone.
Redundant links work because the AsantéBridge 1012, using Auto-
sense, can determine what media types are available and there-
fore, what connection it should use as the uplink.
Remember the priority sequence in which the hub searches for
an uplink connection:
❏ First priority is given to AUI
❏ Second to 10BaseT, and
❏ Third to BNC.
If, for example, your uplink is connected with BNC cabling and
you then add a 10BaseT cable to the uplink port, the result is that
Auto-sense will detect this and cause uplink traffic to switch from
the BNC to the 10BaseT media because the 10BaseT is considered
higher priority.
For each media type the checking methodology is a bit different.
AUI:
According to the priority scheme described above, AUI is the first
medium to be checked for use as the primary uplink connection.
The AsantéBridge knows to use the AUI port if it senses that a
MAU exists. The presence of a MAU is detected by pins 2 (CI-A)
and 9 (CI-B) sensing the MAU's transformer. As long as a MAU con-
nection is detected, the 3in1 Uplink will use the AUI port. If no
MAU is detected, the hub will switch to the next available
medium in the priority sequence (10BaseT then BNC).
10BaseT:
According to the priority scheme described above, 10T will not
be the active uplink if an AUI connection exists. For the 10T con-
nection, a Link Integrity Test is performed to determine if a link is
available on this port. This test checks 1 of the 2 twisted pairs (RX
pair) that make up a 10T cable. If the test fails and BNC cabling
exists, then the uplink will be switched to the BNC medium.
Configuring a
Redundant
Link
Checking the Link