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MSR 2000- WAN interface- invert transmit and receive clocks


MSR 2000- WAN interface- invert transmit and receive clocks

Hi guys,

I am facing an issue in HP MSR 2000 and 3000 model routers. I am having SIC-4SAE serial interfaces to connect my WAN links. but many times, i was forced to toggle between the "invert transmit-clock and invert receive-clock " commands in the serial interface, to avoid wan link failure. I think this is due to some mis-configuration in the DCE part, that is SDH device of ISP. But in my cisco routers, i never used these commands to rectify the clocking issues.

My doubt is, after configuring it, how these commands work? whether it will force the clocking on the interface on all the time, or it will come to effect only when there is some issue with clocking. 

And what will happen if I configure  both the commands in an interface at same time?

HPE Comware Software, Version 7.1.064, Release 0615P16
Copyright (c) 2010-2018 Hewlett Packard Enterprise Development LP
HPE MSR2003 uptime is 0 weeks, 0 days, 19 hours, 44 minutes

interface Serial3/0
bandwidth 2048
invert receive-clock
invert transmit-clock
ip address x.x.x.x y.y.y.y

~ Unnikrishnan



Re: MSR 2000- WAN interface- invert transmit and receive clocks


Have you checked with ISP for any issue on the media/line, generally you might need to invert the receive-clock/transmit-clock signal on a DTE-side serial interface to eliminate the half clock-period delay on the line. This command is necessary only for some special DCE devices. In common applications, do not invert the clock.

Thank You!
I am an HPE Employee

Accept or Kudo


Re: MSR 2000- WAN interface- invert transmit and receive clocks

Hi, thank you for the reply.

I have checked with ISP, but there is no issue in their part, and my backup cisco router works like a charm without any additional interface commands. Now I have configured both invert transmit and invert recieve clock commands in the same interface of hp router, and then it started working. ( even though I am noticing a time delay in making ospf neighbour ship).

So what will be the logic behind this? and why hpe msr is not able to identify it by itself and do the changes required? I am working with a large quantity of routers and approx 20% I am putting new hpe msr 2000 and 3000 series. so it is very important to identify this issue and troubleshoot.