[Beowulf] Re: Beowulf Digest, Vol 15, Issue 35

[Ed Karns]

Details of this question are best obtained from the Folks at Texas  
Instruments and NEC, the choice for FW hub chip sets ... (  
http://focus.ti.com/analog/docs/ 
articles.tsp?articleType=brc&templateId=5&familyId=361&path=templatedata 
/cm/brc/data/200207_1394landing )

In the distribution trade these are called "hubs" but in effect are  
packet switching port selectors. FireWire being a simple peer to peer  
network with addressed, traffic management processor and I/O for each  
port = FW hubs being a node ... and an FW hub is a part of each port  
set on each system.

Ed Karns
FireWireStuff.com



On Monday, May 16, 2005, at 12:00  PM, beowulf-request at beowulf.org  
wrote:

>
>> Typical 1394 devices have 2 external ports plus an internal port,  
>> interconnected at a sort of "hub", but it's not a passive hub. It has  
>> significant smarts, maybe a "switch" might be a better conceptual  
>> model.
>
>   The term "switch" in the networking world implies something very  
> specific, mostly data isolation.  I've often wondered if FireWire  
> "hubs" do this?  Given the name "hub", I've often assumed a repeater  
> based technology, but I realize that's my networking bias.
> -----
>
> You're right.  1394 "hubs" do "edit" the data heading through.   
> They're not a passive repeater.  However, they do have a capability  
> for very low latency pass through (that is, they're not store and  
> forward, at least at a big scale).