🚀 go-pugleaf

In article <"443*.G=Arne.S=Langmo.OU=runit.O=sintef.PRMD=uninett.ADMD=..C=no."@MHS>, Arne.Langmo@RUNIT.SINTEF.NO (Arne Langmo) writes:
|> We have a remote site connected to our Cray YMP via:
|> 
|> Low-speed-channel -> DX4130 -> FDDI -> DX???? -> E3 -> DX???? -> Ethernet
|> 
|> In this config. there are set up three PCF filters on the link boxes, to
|> limit the access from FDDI to remote site.
|> There are no big error-rates logged on any interface.
|> 
|> Thru this config. they get a preformance of 80-90 kbits/s with FTP from
|> the Cray to a Convex on the ethernet!
|> 
|> I have seen that some kinds of PCF filters can slow down a NSC-router a bit.
|> But can PCF-filters cause such a terrible loss of preformance?
|> 

As with anything, it depends on how it is implemented...  I've never 
seen this kind of degradation of performance, but it is probably possible.

I don't have any numbers to back this up, but I think we have seen that
you get better performance with PCF if you apply it to a specific interface,
rather than applying the filter on an IP number basis.  I would also 
think that applying a filter on "first" or "last" would give you better
performance than applying it on specific IP numbers...  

Also, do you mean you have three separate filters on each box?  This could 
also be a source of the problem...  In general, I try to combine filters
when they all work on the same task.  

--zawada

-- 
Paul J. Zawada                                    KB9FMN
NCSAnet Network Engineer                          zawada@ncsa.uiuc.edu
National Center for Supercomputing Applications   ..!pur-ee!zawada