0

Does VXLAN always require UDP for encapsulation, cant it just send packet with only IP header?

UDP port 4079 may be required for identification, but is there not any other way to identify, like the VNI field?

How can hosts communicate directly with each other once The two NVEs process the address learning and have each other’s MAC address in the NVE’s mapping table, i think they will still require IP network for communication as they dont have a direct connection, can be miles apart

3
  • The VXLAN standard defines it as using UDP. If you would use it directly on IP (if that was possible), it would not be VXLAN anymore.
    – Teun Vink
    Jan 9 '20 at 5:59
  • Ok, still confused as to how can hosts communicate directly with each other once The two NVEs process the address learning and have each other’s MAC address in the NVE’s mapping table, i think they will still require IP network for communication as they dont have a direct connection, can be miles apart Jan 9 '20 at 6:02
  • UDP runs on top of IP. The IP header identifies the source IP, destination IP, and encapsulated protocol (UDP in this case). The UDP header identifies the source port and destination port (4079 per your question) and encapsulates the data. Jan 9 '20 at 6:42
3

Does VXLAN always require UDP for encapsulation,

Yes. VXLAN encapsulates (Ethernet) frames using UDP datagrams.

cant it just send packet with only IP header?

That's not VXLAN, that's "plain"/no tunneling. The point of tunneling is to hide "inner" addressing from the "outer" forwarding protocols. In VXLAN's case, the inner addressing is MAC, the outer is UDP over IP.

UDP port 4079 may be required for identification, but is there not any other way to identify, like the VNI field?

There are various implementation variants. Check your device's documentation. If you plan to use VXLAN over the Internet I'd very strongly suggest VPN for authentication and privacy.

How can hosts communicate directly with each other once The two NVEs process the address learning and have each other’s MAC address in the NVE’s mapping table, i think they will still require IP network for communication as they dont have a direct connection, can be miles apart

A VXLAN tunnel provides a network bridge between the two potentially widely separated endpoints. Frames are tunneled through like the were connected to the same switch/VLAN. Switches connected to the VXLAN bridges learn source MAC addresses in the same way as with any other bridge.

Of course, you require a working IP network between the VXLAN endpoints to create the tunnel.

2
  • I need IP network between the VXLan ENDPOINTS TO TO CREATE THE TUNNEL, THAT IS UNDERSTANDABLE bUT to continue using the tunnel after it has been created, still i would need the IP network internally to keep transmitting frames, this is my doubt Jan 9 '20 at 9:10
  • @PoojaGupta Each tunnel end requires (at least) an IP interface to send/receive UDP datagrams (with a working connection to the far side of the tunnel), and an Ethernet interface to send/receive frames.
    – Zac67
    Jan 9 '20 at 15:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.