On bootup, port-based hardware timestamping is enabled by default on all ports on the 7210 SAS-Mxp, 7210 SAS-R6, 7210 SAS-R12, 7210 SAS-Sx 1/10GE, 7210 SAS-Sx 10/100GE 64SFP+ 4QSFP28, and 7210 SAS-T, and the node processes both transit packets and locally destined PTP packets. Use the ptp-hw-timestamp command to disable port-based hardware timestamping in the following cases:
to allow the node to transparently forward PTP packets when MPLS uplinks are used
when PTP is enabled and used to synchronize and time the node (that is, PTP messages are originated and terminated by the node acting as a PTP OC-timeReceiver or BC)
on ports that receive PTP packets that will be forwarded transparently
When PTP port-based hardware timestamp is disabled, the node does not update the correction field in PTP messages. See the 7210 SAS-Mxp, R6, R12, S, Sx, T Interface Configuration Guide for more information about the ptp-hw-timestamping command.
For example, to enable transparent forwarding of PTP packets over MPLS tunnels, when access ports with SAPs are used to connect the PTP timeTransmitter or PTP timeReceivers, the ptp-hw-timestamp command can be used to disable PTP port-based hardware timestamping on these access ports.
The ptp-hw-timestamp command is only supported on the 7210 SAS-Mxp, 7210 SAS-R6, 7210 SAS-R12, 7210 SAS-Sx 1/10GE, 7210 SAS-Sx 10/100GE 64SFP+ 4QSFP28, and 7210 SAS-T. Port-based hardware timestamping can be used for transparent PTP packet forwarding if PTP is enabled and used to time the node (that is, PTP messages are originated and terminated by the node acting as a PTP OC-timeReceiver or BC).
The following guidelines must be considered for transparent PTP packet forwarding:
By default, PTP port-based hardware timestamping is enabled on all ports at bootup. To allow transparent PTP packet forwarding, the feature must be disabled using the configure>port>no ptp-hw-timestamp command.
On 7210 SAS-Mxp, 7210 SAS-R6, 7210 SAS-R12, 7210 SAS-Sx 1/10GE, 7210 SAS-Sx 10/100GE 64SFP+ 4QSFP28, and 7210 SAS-T, if the ptp-hw-timestamp command is enabled by executing the command on a set of ports, the node processes PTP packets that transit those ports to update the correction field for the packet residence time in the node. This allows accurate computation by PTP time and frequency recovery algorithms on PTP timeReceiver clocks that are connected to those ports.
The command to enable PTP hardware timestamps for packets transiting the node should be configured on both the ingress and egress port where PTP packets are expected to be received and sent from (and where they need to be processed to update correction time). Configuring the PTP hardware timestamp command on only the ingress port or egress port is not recommended because this will result in incorrect updates to the correction field.
For 7210 SAS-R6 and 7210 SAS-R12 platforms with IMM-b (IMMv2) and IMM-c cards, and for the 7210 SAS-Mxp and 7210 SAS-Sx 1/10GE, to enable transparent forwarding of PTP packets over MPLS tunnels, PTP hardware port-based timestamping must be disabled on the access ports where SAPs are configured. These access ports are used to connect to either PTP timeTransmitter or PTP timeReceivers that need to establish and exchange PTP messages transparently. PTP hardware port-based timestamping does not need to be disabled on the network ports where the MPLS tunnels originate and terminate. This means that these network ports can be used for PTP packet exchange when the node is a PTP boundary clock or ordinary clock timeReceiver. If the requirement is to forward PTP packets transparently when MPLS uplinks are not used or when a hybrid port with a SAP is used, PTP hardware port-based timestamping must be disabled on the access port and hybrid port.
On the 7210 SAS-Mxp and 7210 SAS-Sx 1/10GE, PTP messages for the G.8265.1 and IEEE 1588v2 profiles are transparently forwarded only for a VPRN service on which hardware timestamping is enabled on the access port. This restriction only applies to PTP packets that are using IP/UDP unicast encapsulation.
To enable transparent forwarding of PTP packets over MPLS tunnels on the 7210 SAS-T, you must disable hardware timestamping on access ports where SAPs are configured, and on the MPLS tunnel originating and terminating network ports. Consequently, these network ports cannot be used for PTP packet exchange when the node is a PTP boundary clock or ordinary clock timeReceiver.
To use the node as a PTP boundary clock or ordinary clock timeReceiver, you must use separate ports. In other words, a different access port, network port, or hybrid port must be used for PTP message exchange when this node is configured to be a PTP boundary clock or ordinary clock timeReceiver, and it cannot be any of the ports (either ingress or egress ports) on which PTP packets are forwarded transparently.