MediaGateway
User Manual
81
5
PTP AND 802.1AS in the MediaGateway
This chapter explains the current support of the MediaGateway for 802.1AS protocol.
802.1AS is a protocol used between two or more devices to synchronize all of them
through an Ethernet communication. This synchronization allows two or more devices
(one master and one or multiple slaves) to transmit/receive time-critical information
as audio or video through a physical link and assures that all the devices will handle
the same time reference to encode/decode correctly the information.
This special software allows to maintain the synchronization between the 802.1AS
connected devices, receiving, modifying and creating new corrected packets for the
802.1AS protocol, correcting so the possible delays generated for the routing through
the Switch and the propagation delays of the cables.
5.1
Protocol
The software allows MediaGateway to be converted in a time-aware system bridge,
which implements the transport of time-synchronization information and also the
mechanism for the measurement of the propagation delay.
5.2
Transport of time-synchronization information
For the reference case where this communication is established only between two
devices, „Time-aware system i-1“ configured as 802.1as master and „Time-aware
system i+1“ configured as slave, the ports of the MediaGateway („Time-aware system
I”) implement additionally then, in addition, the respective opposite sides of the
communication, one slave port and one master port, as shown in the next image.
