We have a job coming up in a warehouse with some long Ethernet runs for access points. We will be using CAT6 cabling.
If we use standard 802.3af POE switches and access points that are powered 802.3af, my understanding is that the GPER can go in between and the switch should power the GPER and the access point.
Is that correct?
Do they pass VLANs?
Any reason not to use them?
Thanks
Jason
Yes, it will effectively extend your cable and will pass any data you transmit and also will power the device at the other end. It’s like putting a switch in between. There will be a minimal voltage drop, below one Volt, see table at the second page of this file; https://i.mt.lv/cdn/rb_files/GPeR-1565848659.pdf
Does it learn MAC addresses (SVL or IVL?), drop bad frames and add some delay (store and forward), auto-negotiate (possibly different speeds to both ends) like a switch? Or is it a true layer 1 repeater, nothing more?
Also, does it allow 802.3af/at PoE detection/classification with the device at the other end? For this you must draw almost no current at low voltages, so that 25k resistance is still correctly measured.
It’s like putting a switch in between
mmh, thats a delphi-oracle term …
a switch learns mac-adresses … a switch ages mac-adresses !?
so question is: is this a switch, like a two-port-bridge or is it just like patch-port in OVS which says “<->” ?
Good questions…
Also what about MTU it can do?
a switch with 2 ports doesn’t need to learn no MAC addresses and henceforth not responsible for any aging procedures. it neither runs no loop prevention algorythm. whatever is received from port A will be sent out to port B. it is basically a more expensive piece of wire that is manageable 
if it would support different speeds on both ports, it sould then also have buffering to mitigate drops from congestions due to different bitrate frames arrive and leave.
i think its a 2port switch with Poe in to power it and Poe pass-through
a great device
a switch with 2 ports doesn’t need to learn no MAC addresses
of cause there would be no need, neither would be a need for that in a linux-bridge which contains two logical interfaces by my command or a 24-port switch where I only plugged two cables in …
… but they do ! … threrefore my question.
There are Access-Points in the field which communicates power-requirements over LLDP-MED … more questions … !? How would a GPER behave ?
Expecting a pair of GPER … (what is it … … kleine racker : ) ? … tomorrow.
… or how Gertrud would say:
" a field-test is a field-test is a field-test"
“Yes, it will effectively extend your cable and will pass any data you transmit”
data … yep, data is a lot …
so let us concatenate which questions:
studied “https://i.mt.lv/cdn/rb_files/GPeR-1565848659.pdf” thoughtfully … but … I’ve … still … some questions left
… so let’s fill the voids
\Yii
What chip is that? Marvell 88e8041? It’s hard to read from the image…
But that’s a huge chip for such simple device, probably have like 4 ports or even MII interface…
If it does have more ports, maybe there could be GPER version with more than two connectors? So you could branch off cable to the device, like AP… just like you did in the old days of coaxial cable with the T…
most fun is always testing new stuff 
… guess we can skip the ‘unboxing part’, because this is obviously the wysiwyg-approach … no knives … no scissors … no violence needed … and I aggree 100% with it
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first test … brute force !
the big buddy in the foreground is a wireless-ap with two 5GHz-ac- and one 2.4GHz-radios … and it’s eating PoE-power … like … hell
the grey box with yellow patch in the back is a PoE+ Switch … and it’s feeding PoE-power … like … … accordingly
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wuhan-sw# show poe interface GigabitEthernet 1/1
Interface PD Class Port Status Power Used [W] Current Used [mA]
---------------------- -------- ---------------------------------------- --------------- -----------------
GigabitEthernet 1/1 4 PoE turned ON 11.9 225
wuhan-sw#
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when a GPER is plugged inbetween … in a world of plug’n’play … nothing would change ?!
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… the first test ?! … a “PASS” !
all radios up, pnp … nice and easy
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wuhan-sw# show poe interface GigabitEthernet 1/1
Interface PD Class Port Status Power Used [W] Current Used [mA]
---------------------- -------- ---------------------------------------- --------------- -----------------
GigabitEthernet 1/1 4 PoE turned ON 14.4 256
wuhan-sw#
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little more power is used … thats it
wuhan-sw# show lldp neighbors interface GigabitEthernet 1/1
Local Interface : GigabitEthernet 1/1
Chassis ID : DC-08-56-03-22-A0
Port ID : DC-08-56-03-22-A0
Port Description : Alcatel-Lucent Enterprise OAW-AP1231 eth0
System Name : OmniAccess Stellar OAW-AP1231
System Description : Alcatel-Lucent Enterprise OAW-AP1231 3.0.6.28
System Capabilities : Bridge(+), WLAN Access Point(+), Router(-), Station Only(-)
PoE Type :
PoE Source :
PoE Power :
PoE Priority :
wuhan-sw#
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and we learn two things:
wuhan-sw# show poe interface GigabitEthernet 1/1
Interface PD Class Port Status Power Used [W] Current Used [mA]
---------------------- -------- ---------------------------------------- --------------- -----------------
GigabitEthernet 1/1 4 PoE turned ON 16.1 299
wuhan-sw#
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… still fine, when we replace the PoE-Client with a PoE-2-passive-converter and a map-lite
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wuhan-sw# show poe interface GigabitEthernet 1/1
Interface PD Class Port Status Power Used [W] Current Used [mA]
---------------------- -------- ---------------------------------------- --------------- -----------------
GigabitEthernet 1/1 4 PoE turned ON 3.6 70
wuhan-sw#
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less power ! (like out of hell : )
… and very enlightening:
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wuhan-sw# show interface GigabitEthernet 1/1 capabilities
GigabitEthernet 1/1 Capabilities:
Model: 8G-2GF
Type: 10/100/1000BaseT
Speed: 10,100,1000,auto
Duplex: half,full,auto
Trunk encap. type: 802.1Q
Trunk mode: access,hybrid,trunk
Channel: yes
Broadcast suppression: no
Flowcontrol: yes
Fast Start: no
QoS scheduling: tx-(8q)
CoS rewrite: yes
ToS rewrite: yes
UDLD: no
Inline power: yes
RMirror: no
PortSecure: yes
Dot1x: yes
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wuhan-sw#
wuhan-sw# show interface GigabitEthernet 1/1 status
Interface Mode Speed & Duplex Flow Control Max Frame Excessive Link
---------------------- ------- -------------- ------------ --------- --------- --------
GigabitEthernet 1/1 enabled Auto disabled 9600 Discard 1Gfdx
wuhan-sw#
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lldp = transparent, link-speed = per segment
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from map-lite’s point of view …
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at this point more ether-speed tests and some pcaps were planned … (but homeland-administration decided other…wisely) … so we postpone that to the next episode …
Thx for the info
good stuff floaty, thx
Still would be good to identify the switch chip used so we can find the datasheet for it with exact specs…
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… yepp … I thought so … … guess I was to hasty to shoot a bundle 
would be good to identify the switch chip
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Yeah I know … but this reminds of christmas, when I was a child … my sister got a new watch … and I got lot of trouble … and she would not accept ‘my fireforce-truck’ ! as compensation.
To be honest … I already tried, but my little iPhone-crowbar is not the sharpest anymore ( … cause I’m a box-burglar since when I still believed in Santa).
… and what is more … I bought this from company-budget … yepp nobody would screw me over a GPER … but in summary ?!
Maybe someone from the MTik-family here in the forum, can ask R&D what chip is involved and we learn without cracking it open ?!
It’s published for every router-board what chip is soldered … so I couldn’t figure any lyzeums-behaviour ?!
… and when it comes to blackbox-analyzing … you learn about how sharp (or not) your (mental-)tools are …
so:
1st: social engineering (if someone would a decent question call it like that)
2nd: old school (if you put something in and comes more than nothing out, you may be able to figure what’s going on inside)
3rd:
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- at what OSI layer this device work? at L1 like hub, or at L2 like switch?
- what delay does this device add?
- why distance is limited to 1500 m?
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… the DEVICE (aka GPeR [thats from the birth-certificate] acts obviously like a switch
… different ether-speeds … with full-duplex on both sides of the box … that I’ve learned from my ‘network-potty-class-tests’ ( no offense … of cause you neeed a potty for potty-class … )
… MTik is printing two mac-adressess on the type-shield ( broad broad hint ! … no need on a hub for that … and yes … you couldn’t know without a potty)
… also a good question … maybe the lowest, which the soldered ‘switching’-chip would allow … guess the delay is like any other mainstream store-and-forward-switching-chip you find on the market
… cause when you have different speeds on your ether-segments … which is obviously possible … you’re a store-and-forward-switch … by the needs ! 
main score of the product seems to be: enhance GBit/s-connectivity without the fiber-constraints ( workmanship-like … and of cause powering devices, where you don’t wanna have to distribute electrical-power too ) … I wouldn’t expect Usain-Bolt-Perfs
… we have delay on every medium … and we have MAC-layer defined which expects minimum-response-times to fit the protocol
… we add the ‘natural’ delay of the medium with the delay of our (signal-regenerating) switches … and yet we have a boundary … 
… that’s our life Jacky Brown
[ … and also the fiber-man coping with the problem … https://en.wikipedia.org/wiki/Fiber-optic_communication ]
https://en.wikipedia.org/wiki/Shannon_limit
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interesting article indeed … and crazy numbers:
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I didn’t say I agree with all comments there 
… yepp … the discourse had a little drift
… so … STP, 802.1q:
Setup: PoE-Switch<–>GPER<–>passivePoEconv<–>mapLite
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wuhan-sw# show spanning-tree active
CIST Bridge STP Status
Bridge ID : 32768.9A-86-03-28-05-01
Root ID : 32768.9A-86-03-28-05-01
Root Port : -
Root PathCost: 0
Regional Root: 32768.9A-86-03-28-05-01
Int. PathCost: 0
Max Hops : 20
TC Flag : Steady
TC Count : 4
TC Last : 0d 00:01:30
Port Port Role State Pri PathCost Edge P2P Uptime
--------- -------------- ---------- --- -------- ---- --- -------------
Gi 1/1 DesignatedPort Forwarding 128 20000 No Yes 0d 00:01:32
wuhan-sw#
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wuhan-sw is the choosen root-bridge … so I guess the auditorium would diagnose by the 100% … GPER is transparent for Bridge-PDUs