[nsp] kentrox hdlc

Stephen J. Wilcox steve at telecomplete.co.uk
Sun Feb 29 10:49:36 EST 2004

On Sun, 29 Feb 2004, Mikael Abrahamsson wrote:
> On Sun, 29 Feb 2004, Gert Doering wrote:
> > Are you sure your layer 1 things are all setup correctly?  That is,
> > clocking is OK (one side is doing clocking), telco line is OK (you can
> > test that using the loops on the Kentrox iDSU), etc.?
> Yes, all of that is ok, link layer is error free. 
> I get hdlc keepalives (or what looks like it, might be garbled as well) on
> the linux side from the cisco but the cisco doesnt get anything at all on
> its HSSI port (I tried "debug all", doesnt show anything coming in on the
> HSSI port).

I think the dsu mode controls the framing etc.. this should be below link layer, 
I wouldnt expect to see the keepalives unless your link is up so perhaps you're 
right and it is up.. however I think it may be possible to see the data being 
corrupted but only slightly if the framing is wrong (so maybe the controller 
thinks all is well but higher up it spots the errors?)

A lot of speculation here from me :) 

I would check to see if you are getting keepalives or not, they should be easy
to find and verify.. if you debug the serial int on the cisco you should see the
keepalives being transmitted.. if you arent seeing that output then I'd say what 
you're getting isnt hdlc keepalives, perhaps some low level framing/channel 
restart type signals. 

Again I'm speculating here but turning on debug on the cisco may only display 
things from the CPU/IOS side and the T3 hardware is likely structured with the 
low level stuff on the physical interface side and the high level stuff on the 
inside (by the IOS). A debug may not show the real low level clocking and 
framing below a certain layer....

This could prove to be very difficult, perhaps some kind of tap and protocol 
analyser will be a big help to you if you can find someone to help?


> > > I have tried PPP and Cisco HDLC and standard HDLC. The above is the only
> > > thing I can find that would stop this from working?
> > 
> > I agree, this could be a reason, but it's "below" PPP/HDLC.
> Yes, I agree.

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