ISA ISDN TAs WITHOUT NICs == STUPID ?

ISA ISDN TAs WITHOUT NICs == STUPID ?

Post by Francois D. Menar » Tue, 19 Dec 1995 04:00:00



OK Guys, tell me one thing !?!

With 10 Mbps Ethernet chip going at around 6 or 8 dollars like
the new Crystal Semiconductor one that makes possible a board
that is more performant than a 3COM '09 for sub 20$ prices.

Why would any ISDN TA manufacturer build an Internet PC
ISA card that would need a high-speed serial port.

What are the dis-advantages of a PC seeing a TA as
a nic instead of a serial port ?

How important is it to be synchroneous in this packetized world ?
Can you do synchrone over an Ethernet bus ?
How about just forgetting on an unstable software driven
interface and just build on top of a 10 year old and
stable NDIS/PKT/ODI industry that ha jut be quite
happily living with it.

Lemme guess: BOM of a ISA-based internal TA that supports
MPPP

10$ for the PCB
10$ for the Crystal Ethernet Chip
50$ for a 68E356
25$ for all the code
20$ for assembling

Looks like a 199$ retail price to me ;)  Why pay for a Gandalf
5250i or a P50 at 1000$

-=Francois=-

 
 
 

ISA ISDN TAs WITHOUT NICs == STUPID ?

Post by Kevin Kad » Tue, 19 Dec 1995 04:00:00




Quote:

>OK Guys, tell me one thing !?!

>With 10 Mbps Ethernet chip going at around 6 or 8 dollars like
>the new Crystal Semiconductor one that makes possible a board
>that is more performant than a 3COM '09 for sub 20$ prices.

>Why would any ISDN TA manufacturer build an Internet PC
>ISA card that would need a high-speed serial port.

If the PC sees the TA as a NIC instead of a serial interface, then all the
protocol handling has to be in the TA, in the case of PPP with authentication,
this means it also has to have the phone numbers, PAP and CHAP passwords, etc.

That's a lot more horespower and code than for a serial TA, and you're locked
to the protocols and implementations provided by the manufacturer.

Quote:>What are the dis-advantages of a PC seeing a TA as
>a nic instead of a serial port ?

Price, inability to do analog modem, V.110, and other protocols.

Quote:>How important is it to be synchroneous in this packetized world ?
>Can you do synchrone over an Ethernet bus ?
>How about just forgetting on an unstable software driven
>interface and just build on top of a 10 year old and
>stable NDIS/PKT/ODI industry that ha jut be quite
>happily living with it.

>Lemme guess: BOM of a ISA-based internal TA that supports
>MPPP

>10$ for the PCB
>10$ for the Crystal Ethernet Chip
>50$ for a 68E356
>25$ for all the code
>20$ for assembling

>Looks like a 199$ retail price to me ;)  Why pay for a Gandalf
>5250i or a P50 at 1000$

Add another 0 to the price of the code and you're close. An ISDN NIC needs
more than just a basic PPP stack...

 
 
 

ISA ISDN TAs WITHOUT NICs == STUPID ?

Post by Fred R. Goldste » Tue, 19 Dec 1995 04:00:00




Quote:>Why would any ISDN TA manufacturer build an Internet PC
>ISA card that would need a high-speed serial port.

Different strokes for different folks.  I'm using a Gandalf 5242i, which
takes Ethernet from the PC and sticks it on ISDN.  No muss, no fuss, and
the Ethernet card was cheaper than a good serial card.

Quote:>What are the dis-advantages of a PC seeing a TA as
>a nic instead of a serial port ?

It wasn't until Warp Connect came out that I could run OS/2 native TCP/IP
over it, since the inexpensive (FREE) TCP/IP with OS/2 Warp (not Connect) is
Serial Port only.  Fooey.  Also, Ethernet ports don't work as well with
dynamic IP addresses, since a lot of software as well as router-class
devices have trouble with the whole idea.  Bridge-class devices work better
for dynamic IP but have other issues.  (I use static.)

Quote:>How important is it to be synchroneous in this packetized world ?
>Can you do synchrone over an Ethernet bus ?

You can't do sync over cheapo async serial or Ethernet, but it's a minor
niche, since modern TAs do async-to-sync or Ethernet-to-sync-HDLC.

Quote:>Lemme guess: BOM of a ISA-based internal TA that supports
>MPPP
>10$ for the PCB
>10$ for the Crystal Ethernet Chip

You don't need an Ethernet chip for an internal card.  You just need
the right glue logic on the ISDN and HDLC logic.  You'd need a lot of
glue on board to link Ethernet to ISDN.  Sort of the same as in the 5242i,
P25, etc.  Of course you'd still need compression support too, etc.
No free lunch.
--

Opinions are mine alone; sharing requires permission.
 
 
 

ISA ISDN TAs WITHOUT NICs == STUPID ?

Post by Oliver Jon » Tue, 19 Dec 1995 04:00:00




Quote:>...
>How important is it to be synchroneous in this packetized world ?

Well, voice and H.320 video require synchronous access to
the B-channel data on ISDN.

But, typical high-speed serial ports don't work properly for that kind
of access anyhow.

Quote:>Can you do synchrone over an Ethernet bus ?
>How about just forgetting on an unstable software driven
>interface and just build on top of a 10 year old and
>stable NDIS/PKT/ODI industry that ha jut be quite
>happily living with it.

You make a good point, especially considering the relative cost
of developing the ISDN product and getting it approved for sale
worldwide.  A one-size-fits-all strategy can be compelling.
 
 
 

ISA ISDN TAs WITHOUT NICs == STUPID ?

Post by pat_boul.. » Thu, 21 Dec 1995 04:00:00





>>Why would any ISDN TA manufacturer build an Internet PC
>>ISA card that would need a high-speed serial port.
>Different strokes for different folks.  I'm using a Gandalf 5242i, which
>takes Ethernet from the PC and sticks it on ISDN.  No muss, no fuss, and
>the Ethernet card was cheaper than a good serial card.
>>What are the dis-advantages of a PC seeing a TA as
>>a nic instead of a serial port ?
>It wasn't until Warp Connect came out that I could run OS/2 native TCP/IP
>over it, since the inexpensive (FREE) TCP/IP with OS/2 Warp (not Connect) is
>Serial Port only.  Fooey.  Also, Ethernet ports don't work as well with
>dynamic IP addresses, since a lot of software as well as router-class
>devices have trouble with the whole idea.  Bridge-class devices work better
>for dynamic IP but have other issues.  (I use static.)
>>How important is it to be synchroneous in this packetized world ?
>>Can you do synchrone over an Ethernet bus ?
>You can't do sync over cheapo async serial or Ethernet, but it's a minor
>niche, since modern TAs do async-to-sync or Ethernet-to-sync-HDLC.
>>Lemme guess: BOM of a ISA-based internal TA that supports
>>MPPP
>>10$ for the PCB
>>10$ for the Crystal Ethernet Chip
>You don't need an Ethernet chip for an internal card.  You just need
>the right glue logic on the ISDN and HDLC logic.  You'd need a lot of
>glue on board to link Ethernet to ISDN.  Sort of the same as in the 5242i,
>P25, etc.  Of course you'd still need compression support too, etc.
>No free lunch.
>--

Except for the draw on the processor and IRQ's, a serial link is
better than an ethernet to ISDN synch. conversion.  The above concerns
will be less of a problem as processors improve even more.  In
addition, running it through a serial port keeps IP off the LAN,
allowing you to route or gateway if you wish.

Patrick Bouldin          :    Gig 'em!   TAMU '83
214/218-6000             :    
TeleTeam Internet        :    ARS KM5L _ _ ...    ..._ _

 
 
 

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