On Tue, 15 Jan 2002, Jean-Francois Dive wrote:
> We have to setup a connection to the megalink service for a customer from
> a linux box. Telstra does not have a lot of information about what you
> gonna have when you take the service, so maybe someone of you knows more
> than them about it.
>
> Here is what i understand from this service:
>
> - It is based on E1 type of link and you receive the appropriate number of
> slots depending on the bandiwth you required.
Nope. A "Megalink" is a dedicated, 2 megabit per second, point to point
service.
What you want is a Primary rate ISDN service, {assuming you do want what
you described}, which you can buy in 10, 20 or 30 channel variants.
> - Now the point is to know how Telstra terminate the network at the
> customer premise, which will change the type of interface we have to
> support: will it be an E1 connection (then which type of connector: RJ48
> or dual BNC type of connector (120 or 75 ohm), what about the CSU/DSU ?),
> or will they give a box which transform the E1 framing to a classical WAN serial
>connection (V35
> type of connection) ? This latest configuratio is the one we have for our
> own framerelay connection, but nobody here is sure if this was included by
> telstra or if we had to finance the box.
Depends what you actually buy. A proper megalink will be terminated on an
orange box {which I used to know the name of - god, old age sucks!} with
coaxial connectors - it's been so long since I did this
that I can't remember the exact details, but I *think* they're RG96
connectors on a high grade 50 ohm coax - but I could be completely wrong.
Anyway, this pair of coax cables {transmit and receive} go to a 2 megabit
per second modem - the only ones I ever used were Scitec Saturn2000's or
2001 - which has either a V35 or X.21 interface.
>From here, you connect to your router with the appropriate cable - V35 or
X.21.
If you really want an ISDN service with multiple channels, you will be
terminated to either an RJ45 connector with ISDN pinouts, or even more
simply to a krone block in your frame, and you have to bring it out to
your RJ45 yourself.
If you want a frame relay service, it's different again - you'll get a 4
wire circuit terminated to a DSU with an X.21 interface {V35 on request,
but last time I asked for V35, they got really shitty and claimed it was
being phased out, and wouldn't I like X.21?}.
> - We need to get internet access trough this megalink, to the associated
> Telstra servie. What is the used L2 encpas to make the link ? Is it HDLC
> (if yes, Cisco HDLC or not), or framerelay ?
Again, depends on what you buy.
A megalink is a point to point connection which runs HDLC. Nothing else is
necessary.
A primary rate ISDN service can run ppp, ppp-multilink, or frame-relay
over ISDN as you wish. That's up to the router configuration. If you're
connecting to Telstra for internet access, it'll most likely be
ppp-multilink.
If you go for a frame relay service, it'll run most likely run
encapsulation frame-relay, or frame-relay IETF - depends on the other
end's connection.
> - Last point, for my own curiosity, does someone know what type of WAN
> does Telstra use for thos services ? Is it a quite legacy E3/E1 etc..
> architecture, or do they use SDH/Sonet or maybe MPLS/IP or MPLS/ATM based
> one ?
Again {I'm saying this a lot!}, depends on the connection you get.
Most of Telstra's network, if it's a long distance connection, is
multiplexed onto the national Sonet fibre ring at some point. Some ISDn
services come into the building as what they call "lightstream" -
basically, they run a fibre into the building and through ATM down it to a
add/drop multiplexer and pull out individual 2 meg streams. This only
happens on large buildings, though, where they can logically expect large
demand for voice/data services.
Sometimes it's plain old copper, with standard ISDN, multiplexed somewhere
upstream from your exchange.
Good luck looking for more detail than that - "Standards? We don't need no
steenkin' Standards!"
DaZZa
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