Specifications

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Cisco MWR 2941 Mobile Wireless Edge Router Software Configuration Guide, Release 12.2(33)MRB
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Chapter 1 Cisco MWR 2941 Router Overview
Features
Clock synchronization
PTP master devices periodically launch an exchange of messages with slave devices to help each slave
clock recompute the offset between its clock and the master clock. Periodic clock synchronization
mitigates any drift between the master and slave clocks.
PTP Redundancy
The Cisco MWR 2941 supports the multicast- and unicast-based timing as specified in the 1588-2008
standard. The Cisco MWR 2941 can use multicast routing to establish redundant paths between an
external PTP client and one or more PTP multicast master clocks.
When configured as a multicast PTP router, the Cisco MWR 2941 selects the best path toward a
Rendezvous Point (RP) using the active routing protocol, sends a Cisco Protocol Independent Multicast
(PIM) join message to the RP, and forwards PTP multicast messages to the PTP client. The
Cisco MWR 2941 also supports PIM forwarding. For instructions on how to configure PTP redundancy
using multicast, see the “Configuring IP Multicast” section on page 4-64.
Hot Standby Master Clock
The Cisco MWR 2941 supports a hot standby master clock for PTP clocking; the Cisco MWR 2941
selects the best clock source between two PTP master clocks and switches dynamically between them if
the clock quality of the standby clock is greater than that of the current master clock. For instructions on
how to configure a hot standby master clock, see the “Configuring PTP Clocking” section on page 4-39.
Hybrid Clocking
The Cisco MWR 2941 supports a hybrid clocking mode that uses clock frequency obtained from the
synchronous Ethernet port while using phase (ToD or 1PPS) obtained using PTP. For instructions on
how to configure hybrid clocking, see the “Configuring PTP Clocking” section on page 4-39.
Pseudowire-based Clocking
Pseudowire-based clocking allows the Cisco MWR 2941 router to
• Transmit and receive clocking information over a pseudowire interface
• Receive clocking over a virtual pseudowire interface.
The Cisco MWR 2941 can transmit clocking information within packet headers (in-band) or as a
separate packet stream (out-of-band).
Pseudowire-based clocking also supports adaptive clock recovery (ACR), which allows the
Cisco MWR 2941 to recover clocking from the headers of a packet stream. For instructions on how to
configure pseudowire-based clocking, see the “Configuring Clocking and Timing” section on page 4-39.
For more information about using pseudowires, see the “Cisco Pseudowire Emulation Edge-to-Edge”
section on page 1-3.
Synchronous Ethernet
Synchronous ethernet is a timing technology that allows the Cisco MWR 2941 to transport frequency
and time information over Ethernet. Because frequency and time are embedded in Ethernet packets,
synchronous Ethernet must be supported by each network element in the synchronization path.
Synchronous Ethernet is defined in the ITU-T G.781, G.8261, G.8262, and G.8264, Telcordia
GR-253-CORE, and Telcordia GR-1244-CORE standards.