Installation and Reference Guide (J3210A, J3212A, J3200A, J3202A, J3204A) 1996-08

E-3
Backup Links
Examples of Backup Links
Backup Links
Note ■ One hub in the stack needs an HP Management Module installed.
■ The port used for the primary link must be on a segment this is
connected to (not isolated from) the main four-segment backplane.
■ The port used for the backup link can be on a connected or isolated
segment, however it is recommended that you put the primary and
backup link on the same segment.
■ Any combination of media types can be used as a backup link by using
the AUI/Xcvr slot. This slot accepts fiber, thin coax, twisted-pair and
an AUI module for external transceivers. For example, a thin coax
link from the ThinLAN port can act as a backup link to a twisted-pair
link.
■ A Management module can monitor up to 4 backup links in a stack.
This would allow for 1 backup per segment or multiple backups on 1
segment.
■ The remote device should have no more than 2 backup links connect-
ed to it from a monitoring hub. If the remote device has more than 2
backup links functioning, it may not be able to respond to the test
packets fast enough when there is a high level of data traffic on the
network segments.
■ This ability to respond may be improved by increasing the time
between test packet transmissions on the monitoring hubs. For all
the backup links in which the remote device is involved, the time
configured on the monitoring hubs for those links should be increased
by one second for each additional backup link beyond two links. Add
one to this count if the remote device is also functioning as a primary
(monitoring) hub for a different link.
Suggestion ■
■ The primary link and the backup link cabling should be run over
different paths (through different conduits, for example) to reduce
the possibility that damage will occur to both cables simultaneously.