NDA_PORT attribute is useless

NDA_PORT attribute is useless

[Stephen Hemminger]

I noticed that this commit is also broken.
Because although you can specify alternate UDP ports for sending,
it does nothing to enable those ports for reception. So although you
can create new static neighbour entries with different ports, they
are useless.

commit 6681712d67eef14c4ce793561c3231659153a320
Author: David Stevens <dlstevens@us.ibm.com>
Date:   Fri Mar 15 04:35:51 2013 +0000

    vxlan: generalize forwarding tables
    
    This patch generalizes VXLAN forwarding table entries allowing an administra
    to:
        1) specify multiple destinations for a given MAC
        2) specify alternate vni's in the VXLAN header
        3) specify alternate destination UDP ports
        4) use multicast MAC addresses as fdb lookup keys
        5) specify multicast destinations
        6) specify the outgoing interface for forwarded packets
    
    The combination allows configuration of more complex topologies using VXLAN
    encapsulation.
    
    Changes since v1: rebase to 3.9.0-rc2
    

Re: NDA_PORT attribute is useless

[David Stevens]

Stephen Hemminger <stephen@networkplumber.org> wrote on 05/17/2013 
11:54:57 PM:

> I noticed that this commit is also broken.
> Because although you can specify alternate UDP ports for sending,
> it does nothing to enable those ports for reception. So although you
> can create new static neighbour entries with different ports, they
> are useless.

On Host A:
modprobe vxlan

on Host B:
modprobe vxlan udp_port=9462

...and whatever you want on any other hosts.

Then you want to connect a segment on Host A and
Host B. The fdb entries on Host A that point to
Host B should use "port 9462"; the fdb entries on
Host B that have destination Host A should use
"port 8472".

And if Host C is an external switch using 4789, its
fdb entries should use "port 4789".

It does exactly what it is supposed to do, allow these
hosts to use VXLAN with each other, and has nothing to do
with listening on multiple ports.

                                                        +-DLS