SONET ring questions

Thu Oct 15 20:54:59 UTC 1998

This is my first posting to the NANOG list.  I don't think this is
off-topic, but if so, please send replies (or flames) directly to me 
(rather than to the list) and I will issue a detailed summary.

We are in the process of implementing an OC-12 SONET ring connection 
between two sites in New Jersey that span a distance of 15 miles.
The SONET ring will be provided by Bell Atlantic and is composed of
fully redundant hardware (there are no single points of within the
telecom equipment) and redundant rings.  We are splitting the OC-12 
into pairs of OC-3's on two routers in each location (running ATM on
the WAN).  This interface is extremely mission critical to the point 
that a 99.9% uptime will not be acceptable.  I have the following 
questions:

1) Bell Atlantic assures us that, because of the redundancy, we can
   expect 100% uptime from the OC-12.  I would like feedback as to 
   whether this is a realistic portrayal of the SONET environment.

2) We have the option of using either single-mode or multi-mode fiber 
   OC-3 connections - what factors should be considered in selecting
   the fiber media type.

3) Which routers should be used.  The options are 3com NB-II's DPE+
   (dual CPU), Cisco 7200 series, or Cisco 7500 (each router will 
   have at least two 100Base-T LAN ports).  OK, I know the 3com 
   suggestion is a loaded question for this list, but has anybody
   used the 3com's in this capacity?  We are a 3com shop that is 
   considering switching to Cisco - this is a significant decision 
   because switching will require us to continue to maintain the 
   existing 3com environment (~500 routers) and the new Cisco 
   routers.

Thanks,
Peter Polasek