North American Network Operators Group

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Re: Converged Networks Threat (Was: Level3 Outage)

  • From: David Meyer
  • Date: Wed Feb 25 13:38:54 2004


>> > 	Is your concern that carrying FR/ATM/TDM over a packet
>> > 	core (IP or MPLS or ..) will, via some mechanism, reduce
>> > 	the resilience of the those services, of the packet core,
>> > 	of both, or something else?
>> 	I'm saying that if a network had a FR/ATM/TDM failure in
>> the past it would be limited to just the FR/ATM/TDM network.
>> (well, aside from any IP circuits that are riding that FR/ATM/TDM
>> network).  We're now seeing the change from the TDM based
>> network being the underlying network to the "IP/MPLS Core"
>> being this underlying network. 
>> 	What it means is that a failure of the IP portion of the network
>> that disrupts the underlying MPLS/GMPLS/whatnot core that is now 
>> transporting these FR/ATM/TDM services, does pose a risk.  Is the risk
>> greater than in the past, relying on the TDM/WDM network?  I think that
>> there could be some more spectacular network failures to come.  Overall
>> I think people will learn from these to make the resulting networks
>> more reliable.  (eg: there has been a lot learned as a result of the
>> NE power outage last year).

	I think folks can almost certainly agree that when you
	share fate, well, you share fate. But maybe there is
	something else here. Many of these services have always
	shared fate at the transport level; that is, in most
	cases, I didn't have a separate fiber plant/DWDM
	infrastructure for FR/ATM/TDM, IP, Service X, etc,  so
	fate was already being/has always been shared in the
	transport infrastructure. 

	So maybe try this question: 

	  Is it that sharing fate in the switching fabric (as
	  opposed to say, in the transport fabric, or even
	  conduit) reduces the resiliency of a given service (in
	  this case FR/ATM/TDM), and as such poses the "danger"
	  you describe?    

	Is this an accurate characterization of your point? If
	so, why should sharing fate in the switching fabric
	necessarily reduce the resiliency of the those services
	that share that fabric (i.e., why should this be so)? I
	have some ideas, but I'm interested in what ideas other
	folks have.