Cell Relay Archive

[Tim <2207leung@hknet.com>]

Kevin Fleming wrote:
> 
> Fahad A Hoymany wrote in message <6p1v8n$348$3@usenet01.srv.cis.pitt.edu>...
> >Hi,
> >
> >        Our network provider says they cannot provide us with an optical
> >interface to their network.  They can only give us an E3 electrical
> >interface.
> 
> It looks like they have only E3 ports available to you, the user, or there
> are some regulatory/commercial reasons why they don't want to offer STM-1,
> or they have to carry you over a transmission system to you local Point of
> Presence (which my not be as close as you think...)
> The E3 is carried over fibre, to be sure, to you local exchange - but it
> sounds like it is then carried over SDH to the ATM switch.

The E3 is the PDH interface standard. Its spec should be referred to
G703. It is intended to be carried over copper wire or coaxial cable.
> 
> > We want an STM-1 interface (155Mbps) but it seems that Cisco
> >does not have electrical interfaces for that speedit only has optical
> >interfaces for STM-1.  The questions are:
> >
> 
> Do you need 155Mbps of bandwidth...?
> 
> >1. Does it matter if you use electrical or optical STM-1 interface?
> 
> Electrical STM-1 operates to a couple hundred metres (or even less, not too
> sure) over coaxial cable.  It is a common interface on SDH line systems
> which are intended for intra-office use (office=exchange)
> 
> >2. If they give us an electrical interface to their network, does that mean
> >the actual signal over the fiber link (into their network) is electrical?
> >Is it even possible that an electrical signal be carried over a fiber line?
> >
> 
> I refer you to James Carlson's responses to these questions .
> 
> >Thanks in advance
> >Fahad
> >
> 
> Hope this helps,
> Kevin.