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SyncE on LACP members

Hi Everyone!


I'm working with ASR9010 with 6.6.3 and I wonder if this is supported.


We have to deploy SyncE and all interfaces are bundle members. G.8264 amd1 says:


"It is also important to note that the use of parallel links, such as the case with LAG, needs to be carefully considered due to the potential for creation of timing loops (see clauses 5.13.2 and of [ITU-T G.781]. As noted in clause 5.13.2 of [ITU-T G.781], the concept of a "bundle" is introduced in cases where multiple timing links share the same synchronization source (i.e., the same EEC in the case of synchronous Ethernet). In this situation, which also applies to LAG, when a network element selects one port of a bundle as its synchronization input, it has to return DNU/DUS (do not use/do not use for synchronization) on all timing capable ports of the bundle. It is left to the operators either to configure several synchronous Ethernet enabled ports or only one synchronous Ethernet enabled port of the LAG."


For short: To avoid sync loops, if a bundle member is used as sync source, the router should send DNU in  response to all members.


In my lab it doesn't work this way. Every link es treated as a different source. Do I need a specific configuration? I couldn't find any helpful info about this. 


Fl Interface QLrcv QLuse Pri QLsnd Output driven by
==== ======================== ===== ===== === =====

>S TenGigE0/0/0/26 PRC PRC 20 DNU TenGigE0/0/0/26
>S TenGigE0/0/0/28 PRC PRC 20 PRC TenGigE0/0/0/26


Thanks a lot!

Mark Pace Balzan



I'm not sure i fully follow what you are doing, but here is how I handle it and it works. Note I am working with G8275.1 which is essentially layer2 based. This means that I configure synce for 75.1 on one bundle member phy interface only as its not supported on the bundle for G8275.1


If you are also using ptp on G8275.2 this is where you may have issues with lacp due to packet delay variation when different packets select different bundle members and therefore cause delay variation which kills ptp


Hope this helps even if its not a direct answer to your question