Transcript The Great Network Storm of ’03 A Cast Of Thousands EPICS

EPICS
The Great Network Storm
of ’03
A Cast Of Thousands
EPICS
History
• In a May 31, 2003 message to tech-talk
Lawrence Hoff (Brookhaven National
Laboratory) mentioned:
• memPartInfoGet bug which corrupted the heap (!!)
• a Wind-River Systems Software Problem Report
of ill-formed Ethernet packets causing multicast
storms.
• that BNL had worked around the bug by disabling
IP forwarding
EPICS
Summary
• HP89441 VSA sends malformed packet
• All devices on ‘.2’ subnet receive packet
• vxWorks bug causes IOCs to forward
packet back to the network (!!)
• Exponential increase in network traffic
(theoretically 24064 ≈ 2x10158 packets)
• Control system grinds to a halt
EPICS
The HP89441 as seen
by the APS control system
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
EPICS
Short-Term Solution
Stop the IOC which was communicating with
the HP89441.
Disable packet forwarding in as many IOCs
as possible
IOCs with associated MVME162 card must have
packet forwarding enabled
Devices over which we have not control have
packet forwarding enabled
Any N>1 is going to make N64 a big number!
EPICS
Real Solution
1. Add packet filter to network switch
Not possible with our switches
Testing ‘home-network’ 2-port router
2. Fix bug in all vxWorks machines
More than just IOCs
3. Fix bug in HP89441
HP/Agilent aware of problem
EPICS
Warning!
YOUR SYSTEM
COULD BE NEXT!