Describes a PTP clock mode that supports multiple VLANs on Cisco switches.
A PTP transparent clock is a clock mode that supports PTP on different VLANs by operating differently from normal transparent clocks in which the VLAN ID of PTP messaging is not changed.
PTP transparent clock characteristics
The Cisco switch supports two PTP VLAN behaviors. The default configuration uses a single VLAN. The multi-VLAN feature must be enabled explicitly.
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When PTP packets are received from the grandmaster clock (GMC) and ordinary clocks (OCs), they are terminated, and new PTP packets are generated based on the PTP port VLAN configuration. That means that PTP packets with different VLAN IDs can be supported on a transparent clock.
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The PTP header and body data from the received packets are copied to the newly created packets at the PTP layer. As a result, DLR ring switches and PTP endpoints connected to DLR ring switches do not see any PTP parent change after a DLR ring fault or recovery.
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The PTP port VLAN configuration and behavior are the same as those in boundary clocks.
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On access ports, the access VLAN is used to transmit and receive PTP packets.
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On trunk ports, by default, the trunk native VLAN is used to transmit and receive PTP packets.
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On trunk ports, the interface level CLI command ptp vlan vlan_id is supported to configure the trunk nonnative VLAN used to transmit and receive PTP packets. PTP packets are transmitted with a VLAN tag when the nonnative VLAN is configured as the PTP VLAN.
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The ptp mode e2etransparent multiple-vlan is introduced in the Cisco IOS XE 17.13.1 release, applicable only for Cisco Catalyst IE3400 Rugged Series Switches and Cisco Catalyst IE3400 Heavy Duty Series Switches that support DLR.
For details about boundary and other clocks, see the section 'PTP Clocks' in the chapter 'Configuring Precision Time Protocol guide.