MurphyMc
commented
4 years ago Just create an instance of organizationally_specific. Then set the .oui and possibly the .subtype to something that identifies you (e.g., your organization's OUI) and your custom type. Then set the .payload to a random UUID and timestamp however you want to do that. For example, you could make it human-readable and just make payload a string containing "{uuid...} timestamp". I think that's all there is to it.
If I recall correctly, getting discovery to send additional TLVs should be as simple as appending them to the list with the other TLVs: https://github.com/MurphyMc/pox/blob/fangtooth/pox/openflow/discovery.py#L194
However, I think the current version pre-generates the LLDP messages and recycles them. If you want a fresh timestamp, you'll need to generate them on the fly instead. The current pre-generation is done in add_port(); it calls create_packet_out() to do the actual packet generation, wraps the resulting packet in a SendItem() and then adds it to the list of packets to send each cycle. I think the easiest fix is to have the SendItem() contain the tuple (dpid, port_num, port_addr) instead of the packet. Then when sending (in _timer_handler()), use those as parameters to create_packet_out() then.
Then you'll want to modify the PacketIn handler: https://github.com/MurphyMc/pox/blob/fangtooth/pox/openflow/discovery.py#L342
I think you'll want to iterate through the list of TLVs looking for ones of tlv_type==ORGANIZATIONALLY_SPECIFIC_TLV. When you find one, check if it's got your OUI and subtype. If so, parse its .payload.
joekutos
The i am trying to create a custom LLPD packet by adding my own organisationally_specific TLV field. ` class organizationally_specific (simple_tlv): tlv_type = lldp.ORGANIZATIONALLY_SPECIFIC_TLV
def _init (self, kw): self.oui = '\x00\x00\x00' self.subtype = 0 self.payload = b''
def _parse_data (self, data): (self.oui,self.subtype) = struct.unpack("3sB", data[0:4]) self.payload = data[4:]
def _pack_data (self): return struct.pack('!3sB', self.oui, self.subtype) + self.payload
My field just has a random UUID and a TIMESTAMP. what code changes should be done to be able to add these custom tlvs plus the <discovery.py > such that the added tlvs can be sent out in the packet out message during the discovery process.def create_packet_out (self, dpid, port_num, port_addr): """ Create an ofp_packet_out containing a discovery packet """ eth = self._create_discovery_packet(dpid, port_num, port_addr, self._ttl) po = of.ofp_packet_out(action = of.ofp_action_output(port=port_num)) po.data = eth.pack() return po.pack()@staticmethod def _create_discovery_packet (dpid, port_num, port_addr, ttl): """ Build discovery packet """
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