7705 SAR Interfaces
146
Interface Configuration Guide
3HE 11011 AAAC TQZZA Edition: 01
3.2.17.3.3 1+1 HSB
MWA uses 1+1 HSB to protect against microwave link, MPR-e radio, and Packet
Microwave Adapter card failures, as well as frequency channel selective fading.
Additionally, hitless (errorless) switching provides zero packet loss if a switchover
occurs from a main to a spare MPR-e radio.
The following are required for 1+1 HSB:
• one frequency channel
• two MWA Gigabit Ethernet ports (configured in network mode) on two different
Packet Microwave Adapter cards installed in adjacent slots (for example, slot 1/2
or slot 5/6); port 1 on one card protects port 1 on the adjacent card, port 2
protects port 2 on the adjacent card, and so on.
• two MPR-e radios (one main and one spare), each connected to one of the MWA
Gigabit Ethernet ports on a Packet Microwave Adapter card
The following protection schemes make up 1+1 HSB:
• 1+1 Equipment Protection Switching (EPS)
• 1+1 Transmission Protection Switching (TPS)
• 1+1 Radio Protection Switching (RPS)
• 1+1 HSB Transmit Diversity Antenna (TDA)
These protection schemes are enabled using the config>port>mw>protection
command, with the exception of Transmit Diversity Antenna, which is enabled via the
MCT. They interwork with each other as described in the sections that follow.
1+1 Equipment Protection Switching (EPS)
EPS protects against MPR-e radio, MWA Gigabit Ethernet link, and Packet
Microwave Adapter card failures. After the radio frames are processed by the active
EPS MPR-e radio, the radio sends the Ethernet traffic down to the 7705 SAR-8 or
7705 SAR-18. The standby EPS MPR-e radio does not send any Ethernet traffic
down to the 7705 SAR-8 or 7705 SAR-18.
The switching criteria for EPS are:
• an MPR-e radio hardware failure
Note: An MPR-e radio that is connected to an odd-numbered port on the Packet Microwave
Adapter card must be configured as the main radio.
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