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Cisco Bug: CSCvj14441 - PTP GM clock sync loss after switchover

Last Modified

Jan 20, 2019

Products (16)

  • Cisco Nexus 7000 Series Switches
  • Cisco Nexus 7000 10-Slot Switch
  • Cisco MDS 9710 Multilayer Director
  • Cisco MDS 9148S 16G Multilayer Fabric Switch
  • Cisco Nexus 7000 4-Slot Switch
  • Cisco MDS 9250i Multiservice Fabric Switch
  • Cisco Nexus 7700 6-Slot Switch
  • Cisco Nexus 7700 18-Slot Switch
  • Cisco MDS 9396S 16G Multilayer Fabric Switch
  • Cisco Nexus 7000 18-Slot Switch
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Known Affected Releases


Description (partial)

Nexus 7000 running 8.2(1) with N77-M348XP-23L and N77-SUP2E linecards. PTP stops working after a switchover takes place. Issue was narrowed down to a lack of PTP multicast address Membership reports from Nexus 7000 after a Switchover takes place. 

Due to this lack of Membership reports, PTP announcements from GM clock are no longer received via the layer 2 switch sitting in between, hence the Nexus stops seeing the GM clock and claim itself as the new GM clock.

-PTP enable on l3 port on N77-M348XP-23L linecard
-Layer 2 switch sits in between GM clock and Nexus
-Layer 2 switch in between has an IGMP group for reserved address 
-Port connecting to GM clock and Nexus show up as interested parties. 
-Switchover takes place and Nexus 7000 stops responding to general queries and does not joing any more
-Eventually layer 2 switch in between stops forwarding traffic to Nexus, so PTP announcements from GM clock are no longer seen. 
-N7k will clain itself as the new GM clock.
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