MAC/PHY Filtering

[lpcware]

Content originally posted in LPCWare by jnewell on Fri Sep 20 11:20:26 MST 2013
Hey,

Has anyone experimented with filtering out packets from a specific ip addresses with the LPC1768 and LAN8720? (I'm using lwip and freeRTOS)

I'm having an issue when one of my high bandwidth streaming devices is running on the network at the same time that I'm trying to receive a different stream, seems like the PHY is just constantly receiving stuff, and the processor can't keep up with it.

If I use a multicast switch, I don't have the problem because then my device only receives packets from the specific multicast group that it joins.

-Josh

[lpcware]

Content originally posted in LPCWare by MikeSimmonds on Sat Sep 21 04:52:09 MST 2013
You can't filter out, but you can filter in.

Set your boards MAC address in to the three station registers
[NB recall the reversing issue thread http://www.lpcware.com/content/forum/lan8720a-issues post 16]
and set to allow only unicast multicast and broadcast as shown in the same post.

You need broadcast for ARP requests so the remote sender(s) can get the MAC addr for the IP addr.

Then only packets addressed to your IP will be received and passed on to the CPU.

You'll have to dig into LWIP to see where this should be done [probably a LPC176X specific file to do with EMAC init]

Hope this will help.