Auto MDI/MDI-X + conference rooms + bored == loop
Chuck Anderson
cra at WPI.EDU
Fri Mar 26 22:09:22 UTC 2010
Anyone have suggestions on Ethernet LAN loop-prevention? With the
advent of Auto MDI/MDI-X ports on switches, it seems way too easy to
accidentally or maliciously create loops between network jacks. We
have bored or inattentive people plugging in patch cords between
adjacent network jacks. STP for loop-prevention isn't working so well
for us.
STP "edge" or "portfast" or "faststart" modes are required for
end-station ports (with normal STP, DHCP often times out after 30+
seconds it takes to go into Forwarding state). Since the "edge" STP
mode goes into Forwarding state immediately, there is a period when
loops will form, causing havok with upstream gear until STP blocks the
port (if it ever does see below).
"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?
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?
Thanks for your suggestions/discussion.
--
- Chuck (354 Days until IPv4 depletion: http://ipv4depletion.com/)
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