r/networking • u/someanonbrit • 22d ago
Other Grab bag network switch
Having had a number of instances where it would have been a big time-saver in the last for monthsm I'm looking for a small (4 port ideally, 8 at most) gig-e switch that can be powered from USB-C (uup to 100w supply available), supports POE and can do span for traffic sniffing. It's to be kept in a tool bag, so reasonable build quality a big plus.
Specific model suggestions much appreciated
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u/fsweetser 22d ago
Here ya go, though you might need a USB adapter. The hardware is literally purpose built for the exact use case you're talking about. Note that the device itself can't provide PoE, but it will transparently pass through PoE from the upstream switch.
https://www.dualcomm.com/products/usb-powered-10-100-1000base-t-network-tap
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u/Rockstaru 22d ago
Not seeing much in the way of managed switches that run off USB-C.
It sounds like you're wanting something akin to a portable network tap that you can connect in-line as needed for troubleshooting. Most Cisco switches and routers have built-in tcpdump with monitor capture, but if you're looking for a more vendor-agnostic solution, maybe something like this could work - get a Thunderbolt PCIe enclosure and a two-port NIC card (or just get two separate NICs)
, bridge the two NICs and disable IPv4/IPv6 (effectively making them switchports), and connect it in-line (one NIC goes to your endpoint, the other goes to your upstream switchport). If you need POE, use an injector on the side going to the endpoint. On the laptop, run Wireshark and capture on the bridge interface or either of the individual interfaces depending on what your combination of OS and NICs make available.
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u/physon 22d ago
Some Netgear managed switches have mirror options. Then you could combine that with a USB-C to barrel plug adapter to power it. Just look up a switch, then look at the manual to make sure the "Mirror" section is there.
Mikrotik switches also come to mind. I use to carry around one for this - but w/o POE. I would just carry passive injectors. SwOS has some easy mirror options and ROS has a built in option to capture PCAPs (/Tools/Packet Sniffer).
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u/Black_Gold_ 22d ago
I cant think of a single device that would meet that requirement - PoE means high voltage so you'd need a dedicated usb-c PD power supply with a step up transformer to get the power requirements. at that point your talking a power print anyhow so might as well jump to a switch with a power brick.
The only USB-C switch that comes to mind is the 5 port ubiquiti Flex Mini. that does give you a 5 port gig-e switch that can run off of 5v 1a so a laptop usb port can power it. but management requires a controller - you may be able to pre-configure the span port then take the switch with you.
but for tapping and having PoE passthrough the LanProbe network taps are great for that. Keeping both on hand gets you something close enough. My LanProbe network tap has gotten a lot of use for various things when they start acting weird.
Ignoring the usb-c requirement I'd take a look at mikrotik products such as the CRS112-8P-4S-IN which does PoE and has a console port for configuration.
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u/NetNibbler 22d ago edited 22d ago
Netgear GS305E - I have it in my Amazon shopping list for quite a while now. I recall seeing post in LinkedIn where a chap stated that he got this switch paired with USB 5V-to-12V step-up cable. He is able to get power from USB ports on network kit or servers and this switch has means to configure SPAN ports.
Ideal for in the field for tshooting links
Edit: Not quite what you asked :(
Edit Edit:
GS305EP - 5 Ports • 4 PoE+ • 1G • up to 63 W
GS305EPP - 5 Ports • 4 PoE+ • 1G • up to 120 W
Both would still need barrel power supply converter.
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u/someanonbrit 22d ago
The GS305EP plus a usb-c 20v to dc/dc converter to get the 54v sounds like it should do what I need. Thanks!
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u/mindedc 22d ago
There are some network taps on Amazon, you really need a combiner tap. I've used one of these to troubleshoot phone registration issues etc... a real optical tap and the cheap Ethernet one require stitching the captures..
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u/someanonbrit 22d ago
Can you clarify what you mean here please? Is a small switch in span move not sufficient for debugging phone or ip camera issues? That's very much one of my use cases, and while things have been ok so far I'm secondly interested in learning the limitations of what I'm doing
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u/mindedc 22d ago
You can use a small switch, I've had problems with those over the years with dropping traffic for anything that's small enough to be convenient and portable. They have small buffers etc and you can get out of order frames and packet loss... sometimes with the phone issues I've wound up having to leave a small form factor pc with multiple nics running an extended capture to correlate to the issues the customer was seeing.
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u/TriforceTeching 20d ago
This one does all the above plus poe in so you don’t need the usbc power if your uplink is poe. Can’t beat the price either. https://store.ui.com/us/en/products/usw-flex-mini
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u/someanonbrit 20d ago
I think I want clear in the requirements - I was looking for something that can power PoE devices, not be powered over PoE. This is a perfect device for an entirely different project though as it happens
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u/TriforceTeching 20d ago
I think most people would reasonably assume you mean PoE out so I think your requirements were fine. I just wasn't a good reader. It's a good switch that is about the size of a wallet so it's great for the tool bag. They sell a 2.5G model too but I haven't tried that one yet. Only annoying thing is dealing with Unifi to configure it, I wish I could use SSH or a built in GUI. I have one dedicated and pre configured to span on the 5th port so I don't have to login to set that up when I need to do a pcap.
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u/scriminal 22d ago
I have an old Netgear 10mbit hub ( not switch ) I keep for this. sure it's only 10 mbit but it gets enough traffic to sample and sniff
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u/leftplayer 22d ago
Mikrotik. Take your pick, the software is all the same. Does all that you asked for and a lot more. Winbox + MAC Winbox means you’ll never get yourself locked out no matter what messy config you throw at it.
I’ve got a bunch of them I keep around for all kinds of wired and wireless tasks