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The IT dept say my Ubuntu laptop will cause "broadcast storms and spanning tree collapses." It's not entirely clear how a device on a single connection can cause a spanning tree to collapse; we'll be asking for a detailed technical explanation. We did ask if it "might induce a FUDstorm." We know they run Ubuntu themselves. My boss is defending this assiduously — "we're a Unix department, a Unix laptop is appropriate, Windows isn't" — mostly because he'd quite like it himself, as would several others in the department.

I have new headphones. Skullcandy Ink'd. Apparently they are hip with the kids. Also decent headphones. Wish I'd gotten ones with a side-entry plug. Also, left and right aren't marked. Very good noise blocking for the Victoria Line.

(no subject)

Date: 2009-11-13 12:26 am (UTC)
From: [identity profile] http://users.livejournal.com/_nicolai_/
Some systems in the past have had a feature that the logic runs like this:
Packet enters system via an interface, goes into kernel.
Kernel checks if packet is not destined for the host and packet forwarding (i.e. be-a-router) is on.
If so, kernel looks at its routing table to see where to route that packet.
If no specific route, use default route.

Note the lack of a check for "did it come in this interface?" so the packet can go back out the interface it came in, especially if there's one interface and it's the default exit.

If packet is a broadcast, you can imagine it comes back again. As does any packet on a not totally switched net.
You can get surprisingly large amounts of network out of surprisingly slow CPUs this way...

I expect the only systems with this feature that are still operate are in museums.

March 2022

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