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Forum Topic - VLAN frames transmission using packet filters: (5 Items)

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Muralidhar Duvvuri

02/10/2014 5:00 AM

post108692

VLAN frames transmission using packet filters

I am trying to transmit Ethernet frames with VLAN headers using the packet filter's if_output method. I set the sockaddr
 structure sa_data arguments to hold the destination ethernet address, source address, VLAN tag, VLAN flags and the next
 header type arguments. However, I do not see any packet being transmitted on the wire. If I transmit a frame without 
the VLAN fields, the transmission happens properly. Does it have to do to with the QNX stack not supporting VLAN frame 
transmission or the Ethernet driver? Any insight would be helpful.

Nick Reilly

02/10/2014 8:23 AM

post108693

Re: VLAN frames transmission using packet filters

Have you tried actually creating a VLAN interface and configuring the VLAN ID field on it, and then doing a transmit on 
that?

Muralidhar Duvvuri

02/10/2014 9:43 AM

post108696

Re: VLAN frames transmission using packet filters

I did not create a vlan pseudo interface. I'll try that now. However, from the QNX help, it seems to mention that 
creating the VLAN pseudo interface would fill in the VLAN header and insert it into the packet that is going out. Now, 
my application is itself creating the VLAN header and the Ethernet header and trying to pass the packet directly to the 
driver using the if_output call on a specific interface. In this sceanrio, is it still required to create a vlan pseudo 
interface and map it to the actual interface?

Nick Reilly

02/10/2014 10:02 AM

post108698

Re: VLAN frames transmission using packet filters

It's something I haven't looked in to, but if you want to go that way then I think you will need to have the VLAN stuff 
as part of the data payload rather than in the sockaddr.

Muralidhar Duvvuri

04/02/2014 4:41 AM

post109747

Re: VLAN frames transmission using packet filters

Can you please post a template as to how I can add the VLAN tag as part of the payload? Or if there is some 
documentation which you can point to, that would be great.

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