Cell Relay Archive

[cburkhardt2@home.com]

Peter E. Fry wrote:
> 
> cburkhardt2@home.com wrote:
> 
>   Ah!  Now I see.  (I'd still like to know why you'd run VPCs through a
> 6400 to a RedBack...)
> 
> [...]
> > Can some ATM switches leave a PVC "nailed-up" when a Customer Premise
> > (ADSL modem) equipment is In-Active?  (Hence, good "Segment" F5 Loopback
> > but failed "End-to-End" F5 Loopbacks).  This condition is seen approx
> > 50% of the time we test.
> 
>   This is the only condition I've seen (given a connected path -- VCC in
> the vast majority of cases), and I've seen a few while working at SBC,
> DSL and otherwise.
> 
> > Can some ATM switches "dynamically" activate a PVC ONLY when the
> > Customer Premise (ADSL modem) equipment is Active?  (Hence, failed
> > "Segment" & "End-to-End" F5 Loopbacks).  This condition is seen approx
> > 50% of the time we test.  I know this "dynamic" type of PVC setup sounds
> > self defeating for F5 Loopback tests, but I have not found a positive
> > answer yet.
> 
>   I can conceive the possibility, but have never heard of this type of
> configuration.  I have seen lots of equipment that simply does not
> support OAM (i.e. old), but I've never seen such deployed by a carrier.
> Note that last I heard the Alcatel DSLAM does not respond to segment F5s
> from CPE.  Can't say about the carrier end.
>   I don't know of a method to test particular (i.e. not adjacent)
> segments using F5.  Also, with a VPC I would expect F5 to behave as
> though all possible VCIs are configured/present -- that's been my
> (limited) observation (one customer with an IGX switch).  I could run
> some tests if you like by hijacking equipment that's not mine...
>   Among the odd things I have seen:  Psychotic PVCs that won't pass
> traffic and behave inconsistently when the VPI/VCI is changed, but
> function just fine when terminated on a different circuit; Paths that
> connect in one direction only; etc.  Then again, these are extremely
> rare and should not account for any significant portion of what you're
> seeing.  Any time I'd try to segment ping a PVC and fail I'd feel
> justified in asking the broadband folks to fix the path -- but that's
> with the single provider with which I have any experience: SBC.  YMMV.
> 
> Peter E. Fry

thanks alot.

Chris Burkhardt