1+1 Hot Standby link protection Chapter 1: Product description
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phn-2513_004v000 (Oct 2012)
1+1 Hot Standby link protection
This section is an overview of the concept, operation and interfaces of 1+1 Hot Standby
links.
1+1 Hot Standby overview
The 1+1 Hot Standby feature provides an option for protecting against a single point
equipment failure. It also enables maintenance to be carried out with insignificant impact
on customer traffic. Such maintenance actions include software upgrade and unit
replacement.
In order to protect against failure, extra equipment is required to be installed at each end
of the link compared to a standard 1+0 link. This extra equipment will remain on standby
until it is required to take over in case of equipment failure.
Each end of a 1+1 Hot Standby consists of two CMUs, and either two ODUs for outdoor
deployments or one 1+1 capable IRFU for indoor deployments. The 1+1 capable IRFU
contains two transceivers for the purposes of protection. In addition, each end can be
deployed with either one or two antennas depending on the customer requirements. The
antenna options are described in 1+1 Hot Standby link antenna options on page 1-65. At
the network side, at least one Ethernet switch must be installed at each end of the link.
Detailed network options are described in Planning 1+1 Hot Standby links on page 2-35.
The two CMUs which are installed at the same end of a 1+1 Hot Standby link exchange
information over an interface known as the Protection Interface. This shares the same
physical socket as the Management Port. For configurations which manage the CMU over
the Management Port, an accessory known as the Out of Band Protection Splitter is
required. This splits out the management traffic from the protection interface.
The 1 + 1 Hot Standby feature is only supported in CMUs with Boot Monitor software
Boot-03-00 or later.
Active and inactive units
At any one time at a given end of a 1+1 Hot Standby link, only one CMU will provide the
function of forwarding Ethernet frames between the wireless interface and the Ethernet
interface. Also, only the ODU / IRFU transceiver connected to this CMU will radiate at the
antenna. These units are called the active units.
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