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ASR1002 Clocking

I have two ASR1002 routers that are connected via DWDM (Wavestream) technology. The wavetstream itself does not do clocking.

We have been advised that we need to the following clocking configured on the ASR Routers.

One end needs to be:- INTERNAL

One end needs to be:- RECOVERED

I have checked through on the router, and can see no equivalent values.

Please help :-).

Rising star

Hi Pete,

I'm not familiar with the particular platform, but I guess you have some type of optical interfaces in your routers. In optical router interfaces there typically exists a way to set the clock source to "line" or "internal". See for example the following document:

The default value is usually "line" and I guess that's the equivalent of RECOVERED that was suggested to you (i.e. interface uses the recovered clock from the line). When this is the default you do not need to set this parameter on one of the routers. You just need to pick one router and configure the clock source to "internal" on its corresponding interface (e.g. clock source internal).

Kind Regards,


Hi Maria.

Thanks for posting back so quickly.

I must firstly apologise for posting an initial lask of information originally.

The wavestream circuits compromise of 2 * 1Gig circuits terminated on gig0/0/1 and gig0/0/2 using MM sfp modules, and ospf load sharing.

On gi0/0/1 and gi0/0/2 there doesn't appear to be any clock commands??

Many thanks

Hi Pete,

I must admit I'm not sure what should happen in this case, but I will give it a shot until somebody else with more knowledge comes along, since this seems to be a setup that is not working anyway. Just to be clear, I'm not perfectly sure about what is required. I'm just guessing and hope that there won't be any issues if these routers are in production and have other services already running.

Can you check the the following document:

Is this relevant to your question? It is not clear to me if only a single command would be enough to fix this. In the examples further down the above document I see a "clock source line" command under a gigabit interface, but for this to happen maybe you need to configure the "network-clock input-source" command first for that interface. You can also try "network-clock output-source line" command on the other router. Maybe you can try the other commands in the examples if this is not enough for things to work (e.g. "synchronous mode" under interface). Hope that makes sense.

Kind Regards,


What does your topology look like?

Do the ASR's connect to your DWDM MUX's directly, or do they connec to an intermediate device before hittnig the DWDM network?

DWDM is based on single mode fiber (1550nm), and you said you have multi-mode SFP's (850nm) installed, which won't work, since they ride through completely different wavelength's.

If the routers indeed connect straight into DWDM MUX, you'll need DWDM SFP's, not regular MMF.

Hi, thanks for getting back to me.

The ASR's are connected directly into Cienna Wavestream MUX's. The presentation to our equipment is LC MM presentation.The fibres then connect directly into the ASR routers.

The interfaces on the ASR's are GigabitEthernet.


If that were the case, your Cienna MUX must be doing something more than a straight DWDM MUX, and is converting MM to a SM DWDM channel like an OEO transponder.

We have one equipment that's connected in this fashion, but we didn't need to mess w/ clocking at all.

Have you verified the MM SFP's are functioning properly by plugging them into a local switch?

Also need to make sure the SFP's are recognized by the ASR's and passing validation ("show interface transceiver").

To be honest I'm not sure what else you need to do to bring up that circuit.

I'd be curious to know what Cienna & Cisco have to say though.

Please post your solution when you have it.



Hi all.

I have since found out that it is a bug in the IOS XE CSCtb03171 .

Cisco recommended to upgrade the IOS XE to the following:-


I have loaded this image and the issue cleared straight away.