Multicast; Timing And Jitter - SpectraLink IP-DECT Server 400 Deployment Manual

Synchronization and Deployment Guide

Multicast

The PTPv2 multicast packets cannot traverse routers and consequently the IP base stations
that needs to be synchronized must be on the same switched network segment.
Regardless of the transport selected, IPv4, IPv6 or Ethernet, the network switches must allow
multicast traffic to and from all the LAN base stations. The multicast addresses used are listed
below:
Table 3
Protocol Multicast address
IPv4 224.0.1.129
IPv6 FF02::181
Ethernet 01:1B:19:00:00:00
If IPv4 or IPv6 is used as transport and IGMP snooping
(http://en.wikipedia.org/wiki/IGMP_snooping)
to automatically configure on which ports the multicast packets should be sent. Note that this
requires an IGMP querier to be present on the network segment (many IGMP snooping switches
offers this functionality).
If multicast is not working properly on the network, the IP base stations will not be able to
achieve LAN synchronization.

Timing and Jitter

For PTPv2 to be accurate enough to synchronize the DECT radios the network jitter must be low,
that is the network packet delay must be close to constant.
The PTPv2 algorithms in the base stations have built-in filtering, which make them able to cope
with some level of jitter. However, prolonged periods of large jitter can cause unstable or even loss
of synchronization.
The corporate LAN must support the following specifications:

Maximum of 500 nanoseconds jitter of multicast Ethernet packets between all IP
base stations being synchronized.

Any single switch in the network cannot exceed 100nsec of jitter.

PTPv2 event traffic must be given strict priority over all other network traffic.

Multicast and the IGMP protocol (if used) must be configured per Spectralink
requirements.
Several factors influence the packet delay:
14169000 Version 9.3
October, 2016
is supported by the switch, the switch can utilize this
26