Cell Relay Archive

[neville.aga@mailgate.eiw38.af.mil (Neville Aga)]

How survivable is ATM to fiber cuts? Specifically, I am interested in the 
situation of a capmus environment where ATM is used as a backbone to connect 
different buildings and routers with ATM uplinks are placed on the edges of the 
ATM network (you can see a better drawing at http://132.26.24.232/network.gif)


  PC---Router
	 |
	 |
	ATM
       /    \
      /      \
     / 	      \
   ATM---------ATM
(LANE server)  /
     \        /
      \      / 
       \    /
	\  /
	ATM
	 |
	 |	
	Router----PC




We are planning to move to this type of environment with Cisco Lightstream 
1010, Fore, or similar ATM switches using LANE 1.0. Say LANE has been set up 
and PC #1 is transfering a large ftp file to PC #2. Now, the fiber connecting 
PC #1's ATM switch to the ATM switch acting as the LANE server is cut. What 
happens to the end user and the file transfer. Is a new SVC set up from the ATM 
switch to the ATM switch acting as a LANE server? If so, how long does that new 
circuit take to be set up? What happens to the ftp transfer? Does it continue 
and the end users know no different, or does it have to be manually restarted, 
or is communication between the two nodes dead?

Now, what happens differnt in LANE 2.0? MPOA? IP switching? Do we even have to 
worry about any of this if we only ATM attach routers?

I know SONET has a spec of 50 milliseconds to restore service in the event of 
fiber cuts. Does ATM have a similar spec? Does anyone know of a campus 
environment that is using actual SONET ADM equipment (not just the SONET 
interfaces already on ATM switches) to transport the traffic of their ATM 
swithches in order to retain a survivable capability?

Thank you,
Neville Aga
neville.aga@mailgate.eiw38.af.mil