• Subject: Re: Errors on Token Ring line
  • From: Ray Peterson <rpeterso@xxxxxxxxxxxxxx>
  • Date: Wed, 12 Jan 2000 00:37:30 -0600

Doug ...

Larry Bolhuis wrote:

>   Hmmm. Generally speaking transfers should be similair in both directions.

I think the difference you are seeing is probably just based on the way things 
actually cabled to the MSAU.  Since each port/adapter has to pass the token 
if the destination is the next adapter it will perform better than if it has to 
passed thru three of four intermediate ports.   For example your network might 
like this:

    AS1 <------>AS2 <-------->PC1 <-------> PC2 <--------->HP-PRT <----- back 
to AS1

Now transfers from AS2 to PC1 would be much quicker than from PC1 to AS2 via 
HP-PRT, AS1 as the token moves around the ring.  (I'm assuming traffic is left 
right in above diagram).  The good news is this can be easily improved by 
out the MSAU for a Token Ring Switch.  We use IBM 8272's which come in 8 and 16 
flavors.  We recently bought four used 16 port switches on EBAY for $125/ea.  
would have a tough time justifying the $4,500 original price, but with so many 
dumping token ring, you now often find them on EBAY for $100 or less!  And it 
make those transfers faster!

The switch will allow you full duplex on adapters which support that.  And it
provides cut-thru switching between ports so PC2 could essentially establish a 
path to AS1 or AS2.  It also provides multiple, concurrent paths among the 
ports on
the switch.  Thus you could have a 32mbs path from PC1 - PC2 and a 16mbs path 
AS1 - AS2, compared to a single 16mbs today. Unfortunately, I think the AS/400
adapters are half-duplex only (not 100% sure though!).  Bet Larry knows tho...


Ray Peterson
WITC - Shell Lake
505 Pine Ridge Drive
Shell Lake  WI  54871
715 468-2815

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