[c-nsp] T3 or Ethernet delivery?

[Jason Gintert]

I would go with Ethernet services just for the sheer flexibility.  With
regard to your concerns of monitoring link state, you can use Ethernet
demarcation devices such as the ISG 2X series from Overture to solve that.
Think of it as an Ethernet "Smart Jack".  It provides some pretty neat
testing capabilities (looping, layer 2 ping, etc) and can do things like
fault propagation per EVC.  This means you can have a heartbeat across a
VLAN (you'll need Ethernet Demarcation devices on either side) so if the
heartbeat between devices is lost on the network side it can drop interface
state to your equipment facing ports.  Lastly, there are some great SLA
tools to verify your provider is giving you the service that you are paying
for.  I recommend them highly.

http://www.overturenetworks.com/products/name/ISG2x.html

Jason

> Date: Wed, 08 Apr 2009 00:14:52 -0700
> From: Seth Mattinen <sethm at rollernet.us>
> Subject: [c-nsp] T3 or Ethernet delivery?
> To: cisco-nsp <cisco-nsp at puck.nether.net>
> Message-ID: <49DC4EEC.3070001 at rollernet.us>
> Content-Type: text/plain; charset=UTF-8
> 
> One of my carriers has given me a choice for a new circuit delivery: T3
> or Ethernet. My outside world circuit experience is all non-Ethernet, so
> I have a few questions the sales group wasn't able to answer. I'd love
> to hear some real world experience. The cost difference between the two
> is not significant enough to be the sole deciding factor and I'm not
> using pure-Ethernet platforms so it's just a matter of adding the right
> interface card.
> 
> How do you detect a "down" condition on Ethernet? My experience is that
> the interface could be up/up because Ethernet doesn't know about
> anything further down the line and ends up throwing packets into a
> magical black hole. Or worse, secret packet loss.
> 
> Can you even troubleshoot Ethernet? Normally if I'm seeing something
> like out of frame errors or AIS, I can say "hey, there's a problem and
> it's X". It scares me to think of opening trouble tickets as "it's
> broken and I can't really tell you why".
> 
> With a T3 I can be fairly certain that if there aren't any alarms that
> my end is happily talking to the other end. How does one accomplish the
> same with Ethernet? A periodic "ping" seems rather ambiguous as a health
> check.
> 
> Since this is an outside world connection (i.e. I'm not in a colo) the
> slightly lower cost and convenience factor of Ethernet doesn't override
> my desire to stick with a T3 for its management properties and the
> sleeping good at night feeling I get knowing there are no alarms. My gut
> tells me to stick with it even though Ethernet delivery is what all the
> cool kids are doing these days, so any insight is appreciated. Thanks!
> 
> ~Seth