Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Mon, 16 Jul 2018 13:59:24 -0500

Hi Mark,

On 07/16/2018 12:18 PM, Mark Rivers wrote:
> I thought we were doing directed UDP broadcasts to Cisco switches at
> the APS.
...
> Isn't that doing a directed UDP broadcast to the switch for the
> 164.54.162.* subnet?

If my internal investigations are correct you have an HP ProCurve switch
connecting your two subnets, which is why this still works for you.

Apparently it *is* possible to configure Cisco switches to allow this,
according to the last answer to this StackOverflow question:

https://stackoverflow.com/questions/379015/udp-broadcast-packets-across-subnets

This article from Cisco seems to explain how:
  http://www.ciscopress.com/articles/article.asp?p=330807&seqNum=9

If you have a system available with a network interface on both subnets
you could also run a pair of UDP Broadcast Packet Relays to pass
broadcasts between them, on both ports 5064 and 5065. More information
on this is available at

https://wiki-ext.aps.anl.gov/epics/index.php/How_to_Configure_Channel_Access#UDP_Broadcast_Packet_Relay

- Andrew

-- 
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
speech because I have nothing to say." -- Edward Snowdon

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System