[MVMA] Interest in MVMA AUXCOMM

[Chuck Gelm]

On 11/20/2018 06:40 PM, A Margraf wrote:
> Hey everyone.  I am trying to follow along but I must admit that I get 
> confused at times in discussions like this.
>
> From what I understand you are referring to injecting power on an 
> Ethernet cable (Ethernet power injection) most of the time but it 
> seems some of the time you are referring to POE standards compliant 
> power injection.
>
> The reason it makes a difference to me is my experience with POE phone 
> system components.  The POE standard allows a device to negotiate a 
> voltage and power level. All of this works great but when mixing the 
> two types of systems bad things can happen, namely equipment loss.  
> Some devices are made to allow for Ethernet power injection but 
> require too much power to be POE compliant.
>
> The reason I would like clarification is because I  don’t want to 
> mis-guide anyone or cause damage to mine or their equipment.  I have 
> many devices that are POE compliant and can answer questions about 
> managed POE switches and routers   What I have very limited experience 
> with is actual mesh hardware and system topology.  The experience I do 
> have suggests to me that either there are problems in the routing 
> algorithms (Iknow for sure there have bee) or networks are set up 
> oversimplified for ease of operation.  I have a lot to learn about the 
> way the mesh algorithms work and want to understand how to interface 
> them with more traditional routing algorithms.  I have focused on that 
> part of it because the reality is we may have to make it work 
> seamlessly with commercial systems in a real emergency.    Sorry for 
> writing a novel!
>
> Looking forward to seeing this network grow!
>
> Cheers!
> Andy,  KC8AZW
>
>
Hi, Andy

  Primarily in the MVMA 'mesh' 'POE' means powering 24 DC volt devices.
( These devices: 
https://www.arednmesh.org/content/supported-platform-matrix )
There may also be some 5V (phones) and 48V (cameras) in service.
Do you have a link to a 'POE' RFC or definitions?
I was unaware the 'POE' was a standard.
I know of 802.3af, of which our 'mesh' devices do not use.

Here an AREDN firmware routing algorithm:

"*ETX*
Expected Transmissions (ETX) is a Bernoulli statistic of how many 
packets must be transmitted to successfully receive the round trip 
acknowledgement between Neighbor nodes and is calculated with this 
formula: ETX = 1/(LQ*NLQ).
Between multiple hop nodes, this is calculated by adding up the ETX for 
each single hop.
"1" is a perfect RF link between Neighbors.
A DtDLink is fixed at ETX="0.1" for packets over a cat5 cable.
OLSR on a Mesh Node selects the Neighbor to send traffic to based on the 
lowest cost ETX path towards the final destination Node.

ETX should be interpreted with care.
 From a quality perspective, the ETX for Remote Nodes is not an 
end-to-end metric in the same way as adjacent neighbors.
For example, 2 nodes that are 5 hops apart with zero packet loss between 
them is characterized with an ETX=5.
A single hop with ETX=5 (LQ and NLQ is ~45%) will stream poor quality 
video, if usable at all, given the packet loss.
A 5 hop route between nodes with ETX=5 will deliver smooth streaming 
quality video."

IMO, If there are very good layer 2 links, this algorithm works good.

IMO, AREDN 'mesh' networks will work seamlessly over, under, around, and 
through IP networks.
-----

Shamelessly stolen from
https://en.wikipedia.org/wiki/Power_over_Ethernet
:
"The original *IEEE 802.3af-2003*^[1] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-1> PoE 
standard provides up to 15.4 W of DC 
<https://en.wikipedia.org/wiki/Direct_Current> power (minimum 44 V DC 
and 350 mA^[2] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-2> ^[3] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-3> ) on 
each port.^[4] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-4>
Only 12.95 W is assured to be available at the powered device as some 
power dissipates in the cable.^[5] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-5>
The updated *IEEE 802.3at-2009*^[6] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-6> PoE 
standard also known as *PoE+* or *PoE plus*, provides up to 25.5 W of 
power for "Type 2" devices.^[7] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-standards.ieee.org-7> 

The 2009 standard prohibits a powered device from using all four pairs 
for power.^[8] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-8>
Both of these standards have since been incorporated into the IEEE 
802.3-2012 <https://en.wikipedia.org/wiki/IEEE_802.3> publication.^[9] 
<https://en.wikipedia.org/wiki/Power_over_Ethernet#cite_note-9>"
^
Chuck
^


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