Re: Auto MDI/MDI-X + conference rooms + bored == loop

[Mark Foster <blakjak () blakjak net>]

> "Desktop" switches.  You know, those 4 or 5 port Gigabit Ethernet
> switches.  Apparently, many of them don't do any kind of STP at all.
> Recommendations on ones that do STP?

If the network fabric you're on is important enough to cause you grief in 
the event of a STP event, you shouldn't be fielding 'dumb' switches.

Even the 'dumbest' switch I would ever place into user-space is fully 
managable, layer 2 with VLAN's and STP support.  That is, it's in a 
cabinet or TC and fed by infrastructure cabling, and the only folks who 
can get at it are the engineers and techs supporting the site.

The other side of things is that if DHCP times out once during STP 
negotiation, it rarely times out twice. Users whos machines are 
'dynamically connected' often enough to have STP related glitches in their 
DHCP grab should know enough to hit 'repair' or run ipconfig /renew - or 
should be told to reboot :-)

> RSTP: is it any better than traditional STP in regards to "edge" ports
> and blocking before a loop gets out of hand?  Or perhaps blocking for
> 5-10 seconds before going into Forwarding state, hopefully preventing
> loops before they happen but also allowing DHCP clients to get an
> address without timeouts?  Recommendations on "Desktop" switches that
> do RSTP?

There's plenty of desktop switches out there which are close to 'fully 
featured' - but obviously there's money involved. If your uplink switch 
(at the very least) supports STP then at least you can isolate the 
problem if the switch itself can't handle, but I wouldn't recommend this.

Havn't fielded any recently but there's a fanless version of the Cisco 
2960 I was looking at a while ago for desktop use (fan noise is usualy an 
issue).

Mark.