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Unread 14-03-2015, 17:46
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Travis Hoffman Travis Hoffman is offline
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FRC #0048 (Delphi E.L.I.T.E.)
Team Role: Engineer
 
Join Date: Sep 2001
Rookie Year: 2001
Location: Warren, Ohio USA
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Re: RoboRIO / FMS / mDNS / lessons learned

Quote:
Originally Posted by Mr. Lim View Post
Having competed at GTRC last weekend, I noticed sometimes my students had a lot of difficulty getting a tethered connection to the robot in the pits, possibly due to some of the items raised in this thread.

It's still speculation at this point, but I think it has to do with stale DHCP leases from when the robot and DS were connected to the FMS (10.xx.yy.zz) vs falling back to link-local (169.254.xxx.xxx) in the pits.

If you are connected to the FMS and play a match, the DHCP server will give all your devices a 10.xx.yy.zz address. After leaving the field, when you power cycle the robot, or disable/enable the network connection on the DS, or wait an unspecified amount of time, those devices get a new 169.254.xxx.xxx link-local IP.

If you have one device that still has the IP from the FMS's DHCP, and another with the link-local, the two won't communicate.

The solution we stumbled up is to make sure the robot is power cycled, and the DS's network connection is disabled and re-enabled after every match (to refresh the DHCP lease).

Has anyone else run into this?
*Raises hand*

Nothing new to add. Our experience was as you described.
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Travis Hoffman, Enginerd, FRC Team 48 Delphi E.L.I.T.E.
Encouraging Learning in Technology and Engineering - www.delphielite.com
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