[20539] in North American Network Operators' Group
Re: SONET ring questions
daemon@ATHENA.MIT.EDU (Dave Israel)
Fri Oct 16 11:38:35 1998
Date: Thu, 15 Oct 1998 18:31:54 -0400 (EDT)
From: Dave Israel <davei@biohazard.demon.digex.net>
To: Peter Polasek <pete@cobra.brass.com>
Cc: nanog@merit.edu
In-Reply-To: SONET ring questions (Peter Polasek)
Reply-To: davei@biohazard.demon.digex.net
> 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.
Assuming the primary and backup paths are not in the same cable
anywhere (don't laugh, it happens), the chances of the OC-12 itself
failing inside Bell land are tiny. (Of course, if your local loop gets
assaulted by a backhoe, you're in trouble.)
> 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.
Single mode goes farther. Multi-mode is cheaper. If you've got
relatively short cables, save some money and use multi-mode. If
you're dragging fiber all the way across the building, or between
buildings on a campus, use single-mode.
> 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.
If you go Cisco, I'd recommend the 7500 series. The 7200 series won't
handle two OC-3's and two fast ethers. You'll drop packets.
