[sclug] kvm switch (> 2 port, electronic)

ed ed at s5h.net
Tue Jan 9 20:25:04 UTC 2007

On Tue, 9 Jan 2007 01:55:26 +0000
Matt Dainty <matt at bodgit-n-scarper.com> wrote:

> On 8 Jan 2007, at 18:27, ed wrote:
> > totally irrelevant to the question, but i've had recent experience
> > of the Dell 4161DS. to begin with i set up some ssh tunnels to the
> > remote location and did all the magic so that i could access it, but
> > underneath it's really quite a pain:
> I've used something similar quite a lot, the 2161DS. TBH, it's just
> a rebadged Avocent KVM.

oh, i thought that dell acquired them. i dont know, isn't that what all
the tycoons are doing now? ms just buy things and shove their label all
over it.

> > 1) cannot connect to more than 4 remote boxes at once, despite it  
> > being
> >    labelled as suitable for 128 devices
> >
> > 2) the limit of 4 is total number of clients, so if bob is using the
> >    kvm at the same time, we can only use a total of 4 remote
> > computers
> There's a similar limit with this model, but I've rarely hit it, the  
> KVM tends to be used as a last resort, so if it's only if the
> machine appears to be dead on the network.

oh. right at the moment we're working with another company who look
after a firewall smack bang in the middle of the operation. theory
being that not having one person looking after all the firewalls is
safer... so right now, we cannot remotely connect to everything, so the
kvm is the only way right now.

> > 3) the mouse pointer sucks, some alternative pointing device would
> > be better, like a puck from the old days.
> >
> > 4) it is not always possible to use devices that are on the same
> > 'pem' module. the KVM data is on UTP cable, and we know how much
> > outside interference effects video... so the 'pem' devices are
> > little repeaters for the signal. if bob is using a computer on the
> > same pem, it's not always possible for someone else to work.
> No, I don't think you _can_ use more than one device on the same PEM  
> module, the concurrent client count is based on the physical ports
> on the KVM, so for example you can have 2 concurrent users on any
> two physical KVM ports, so if the two devices are hung from the same
> PEM module, no dice.

almost false advertising... they should make the concurrent limit a bit
more prominent.

> The other problem is that the way the KVM works is by rasterising
> the picture to send it down the wire, and as you've noted, you can
> get interference on the wire, so if the screen starts flickering, the
> KVM sends those flickers down the wire to you which really can
> knacker your bandwidth. I've seen it kill a 2Mb/s leased line.

yes, i've noticed this... the calibrate option sometimes makes things a
bit better.

> > 5) the price tag is $5,000; http://s5h.net/u?f25
> >
> > there are some nice things, like the software is java based, so it
> > can be used on most terminals. but the above things are just so
> > damn ugly that it promises much more than it delivers.
> It's Java based yes, but sadly the actual KVM innards are either a  
> Windows DLL or a Linux/i386 .so library so it doesn't work on a PPC  
> Mac, for example :-( Just shows that Java != Portable everywhere.

ah well, that's not a fault of java... that's a fault of the

it might have been possible for the programmer to tell the kvm how to
move the mouse over IP without having to use system specifics. drawing
the image is just a matter of moving a bitmap to the form... AFAIK that

> Having said that, the little SIP modules for each server makes  
> cabling up a rack quite tidy, there's no bulky KVM cables, just a  
> piece of Cat5 to route wherever.
> > it didn't come from my pocket, and for the location that i'm  
> > working in
> > right now, a kvm is necessary, but these little points are so
> > painful.
> Yeah, I don't think they're great either, but all the servers are  
> Dell so if they also do a KVM, it goes on the order as it's easier  
> than having multiple suppliers/orders. Sadly Dell seem to rebadge  
> someone elses hardware to just say "Yes, we have a KVM-over-IP  
> product", they don't appear to support or maintain it terribly well.

they show the unit as being 0U on their specs... i wonder if thats a
mistake, or how much it's worth...

Regards, Ed                      :: http://www.gnunix.net
just another java hacker
The McRib sandwich only comes back when Chuck Norris is in the mood 
for one. 

More information about the Sclug mailing list