IBM PC Network

[Lyle Bickley]

On Sat, 22 May 2021 23:00:31 -0600
Grant Taylor via cctalk <cctalk at classiccmp.org> wrote:

> On 5/22/21 6:50 PM, Lyle Bickley via cctalk wrote:
> > Wow, never heard of "Tokenray" ;)  
> 
> Nor have I.
> 
> > BTW: 16 Mbit Token Ring was much more reliable (especially in "noisy" 
> > environments) and considerably faster with more consistent performance 
> > than 10 Mbit Ethernet.  
> 
> I've heard tell that Token Ring worked MUCH better on extremely busy 
> networks.  Purportedly Ethernet starts having problems when there are 
> more and more systems and / or a higher and higher percentage of 
> utilization is happening.  I seem to remember that Ethernet had problems 
> starting about 80% utilization while Token Ring could easily handle 95% 
> utilization or higher.
> 
> > plus IBM never upgraded Token Ring past 16 Mbit.  
> 
> Sure they did.
> 
> You can find commercial Token Ring cards that support, 4 Mbps, 16 Mbps, 
> /and/ *100* Mbps.  I see them on eBay monthly.
> 
> I heard that IBM developed 1,000 Mbps / 1 Gbps Token Ring in the lab. 
> But that no commercial products were ever made.

Here's IBM's "Redbook" on Token Ring:

"IBM does not view high-speed Token Ring as a requirement for the majority of
its customers, and therefore the decision has been made not to provide 100
Mbps high-speed Token Ring uplinks on its products..."

Also:

"Note: IBM Statement of Direction, effective October 2001: For z900 server,
this feature is called the OSA-2 Token Ring feature, and can only be
configured as two 4/16 Mbps Token Ring ports. Note: Effective October 2001:
OSA-2 Token Ring feature (feature code 5201) is superseded by the OSA-Express
Fast Ethernet feature (feature code 2366), and OSA-Express Token Ring feature
(feature code 2367), as required. OSA-2 Token Ring feature (feature code 5201)
is not carried forward on G5/G6 server to z900 server upgrades."

To download the Redbook: http://www.redbooks.ibm.com/redbooks/pdfs/sg245975.pdf

Interestingly, in spite of their statement of direction, for a time, IBM did
make a "High-Speed 100/16/4 Token- Ring PCI Management Adapter" (Token Ring
PDF attached...). It was NOT popular - and not many were sold.

Ethernet had "won" the hearts and minds of IT folks (plus Ethernet by that time
was full duplex - at both 100Mbps and 1000Mbps, potentially doubling it's
capabilities). Ethernet also could be implemented for a fraction of the price
of Token Ring. When IBM began to support Ethernet on mainframes, Token Ring
"died" ;)

As a networking company we never installed any 100Mbps Token Ring networks -
and weren't aware of any implemented by our competitors.

Cheers,
Lyle
-- 
73   NM6Y
Bickley Consulting West
https://bickleywest.com

"Black holes are where God is dividing by zero"