System Management
240
Basic System Configuration Guide
3HE 11010 AAAC TQZZA Edition: 01
Figure 17 Ordinary Slave Clock Operation
Each PTP ordinary slave clock is configured for a specific slot where the card (see
Table 26) or Ethernet port (see Table 25) will perform the slave function. On the
7705 SAR-M, 7705 SAR-H, 7705 SAR-Hc, 7705 SAR-A, 7705 SAR-Ax,
7705 SAR-W, and 7705 SAR-Wx, this slot is always 1/1. On the 7705 SAR-X, this
slot is always either 1/2 or 1/3. When the 7705 SAR-M is receiving PTP packets on
the 2-port 10GigE (Ethernet) module, its PTP clock continues to use slot 1/1. Each
slave is also associated with an IP interface on a specific port, adapter card, or
loopback address for the router; however, the IP interface configured on a 2-port
10GigE (Ethernet) module cannot be associated with a slave clock.
For best performance, the network should be designed so that the IP messaging
between the master clock and the slave clock will ingress and egress through a port
where the slave is configured. If the ingress and egress flow of the PTP messages is
via a different port or adapter card on the 7705 SAR, then the packets will be routed
through the fabric to the Ethernet card with the PTP slave.
It is possible that the PTP IP packets may be routed through another Ethernet port/
VLAN, OC3/STM1 or OC12/STM4 clear channel POS, OC3/STM1 or OC12/STM4
channelized MLPPP, DS3/E3 PPP, or DS1/E1 MLPPP. The PTP slave performance
may be slightly worse in this case because of the extra PDV experienced through the
fabric. Packets will be routed this way only if the clock is configured with a loopback
address. If the clock is configured with an address tied to a physical port, the packets
will arrive on that physical port as described above.
CSM B
1588v2
Grand
Master
1588v2
Grand
Master
21307
Ethernet
Ethernet
Ethernet
OC3/STM1
T1/E1/DS3/E3
CSM A
Packet
Network
PTP Slave
Clock
Switch
PTP Slave
Clock
Eth Port
POS Port
PPP/MLPPP Port
Ref2
Ref1
SSU
Eth
Port
Eth
Port
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