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Why not go with 10G? I think 2.5G is a weird use case. You already can get 10G internet in various places, because such connections go over fiber so the ISP co

Why not go with 10G? I think 2.5G is a weird use case. You already can get 10G internet in various places, because such connections go over fiber so the ISP could deliver even 100G if it really wanted to. So if the ISP is already delivering >1G, you can expect things to get to at least 10G eventually, probably sooner than you'll want to rebuild your network. Mikrotik has a whole range of affordable 10G hardware. It's also managed. A lot of it also takes PoE.

martijnvds 4y ago
You can do 2.5G on a single lane of PCIe 3 (maybe also 2?). That makes it way easier to implement electrically. Also, 2.5Gbit uses a lot less power (and generates less heat) than 10Gbit.
- Dylan16807 4y ago
  That one lane will do 8Gbps, so it's not the reason we're using ethernet ports slower than 5Gbps.
vladvasiliu 4y ago
I agree that 2.5/5 are weird use cases, but after a cursory look over this space (so my conclusion may be wrong) I've found that: 1. End devices with 10 Gb ports seem uncommon. The copper variety of adapters seem to run hot, so they're either huge or noisy. This makes them somewhat impractical for the current tendency of "lean" / quiet builds. Whereas most MB seem to have at least a copper 2.5 Gb port, when it's not 5. I've seen USB dongles which are the same size as a Gb one and barely more expensive. 2. The intermediary speeds being "weird", they're not always supported by 10 Gb switches. My Brocade has 10 Gb SFP ports, but they only do either 1 or 10 Gb. I didn't look very hard, but I've never seen any copper module do anything else. Also, 10 Gb copper modules are quite expensive. I've seen managed Netgear switches specifically advertise 2.5/5 Gb copper ports. They're quite cheaper than equivalent 10 Gb switches. Personally, I don't have a use for anything more than 1 Gb (yet) so I've only looked over these things out of a little curiosity. But I can see why people who want to have higher speeds would be interested in these intermediary switches.
- deleted 4y ago
  [deleted]
- bpye 4y ago
  A lot of the 10G copper modules will do 2.5G and 5G, even if the switch only does 10G.
  - vladvasiliu 4y ago
    That's good to know. Since they're usually advertised as the usual 100/1000/10000 I figured they wouldn't be able to negotiate at intermediary rates.
    - bpye 4y ago
      ServeTheHome actually has a summary [0] - I used this to pick one from Amazon. [0] - https://www.servethehome.com/sfp-to-10gbase-t-adapter-module-buyers-guide/ https://www.servethehome.com/sfp-to-10gbase-t-adapter-module...
toast0 4y ago
10G over fiber or DAC is cheap if you get used enterprise equipment, but 10G-BaseT is still expensive. For mikrotik, you can get 8x sfp+ ports for about twice the cost of this switch, then you've got to pay for the tranceivers you want. There's also the question of if existing cabling will work for 10G vs 2.5G, recabling is not realistic for most.
- bpye 4y ago
  If you only need a couple 10G-BaseT ports you can get 10G SFP+ modules which in my experience work well enough. They do get quite hot, but I only needed 10G-BaseT for my desktop whilst everything else at 10G is DAC.
  - AdrianB1 4y ago
    I am on 10 Gbps is parts of my house for a while, 10G on UTP consumes a lot of power and you cannot realistically fill a SFP+ switch with RJ45 transceivers because of that; they are also very expensive for what they provide. At the same time, a SFP+ NIC and a DAC or AOC cable is a lot cheaper and low power. In most cases existing cabling is CAT 5e, you can run 2.5 Gbps with no problem, while 10 G requires re-cabling. This is practically the reason 2.5 Gbps exists: it is the limit of existing Cat 5e infrastructure, just put a switch and you're done.

martijnvds 4y ago

You can do 2.5G on a single lane of PCIe 3 (maybe also 2?). That makes it way easier to implement electrically. Also, 2.5Gbit uses a lot less power (and generates less heat) than 10Gbit.

Dylan16807 4y ago
That one lane will do 8Gbps, so it's not the reason we're using ethernet ports slower than 5Gbps.

vladvasiliu 4y ago

I agree that 2.5/5 are weird use cases, but after a cursory look over this space (so my conclusion may be wrong) I've found that: 1. End devices with 10 Gb ports seem uncommon. The copper variety of adapters seem to run hot, so they're either huge or noisy. This makes them somewhat impractical for the current tendency of "lean" / quiet builds. Whereas most MB seem to have at least a copper 2.5 Gb port, when it's not 5. I've seen USB dongles which are the same size as a Gb one and barely more expensive. 2. The intermediary speeds being "weird", they're not always supported by 10 Gb switches. My Brocade has 10 Gb SFP ports, but they only do either 1 or 10 Gb. I didn't look very hard, but I've never seen any copper module do anything else. Also, 10 Gb copper modules are quite expensive. I've seen managed Netgear switches specifically advertise 2.5/5 Gb copper ports. They're quite cheaper than equivalent 10 Gb switches. Personally, I don't have a use for anything more than 1 Gb (yet) so I've only looked over these things out of a little curiosity. But I can see why people who want to have higher speeds would be interested in these intermediary switches.

deleted 4y ago
[deleted]
bpye 4y ago
A lot of the 10G copper modules will do 2.5G and 5G, even if the switch only does 10G.
- vladvasiliu 4y ago
  That's good to know. Since they're usually advertised as the usual 100/1000/10000 I figured they wouldn't be able to negotiate at intermediary rates.
  - bpye 4y ago
    ServeTheHome actually has a summary [0] - I used this to pick one from Amazon. [0] - https://www.servethehome.com/sfp-to-10gbase-t-adapter-module-buyers-guide/ https://www.servethehome.com/sfp-to-10gbase-t-adapter-module...

toast0 4y ago

10G over fiber or DAC is cheap if you get used enterprise equipment, but 10G-BaseT is still expensive. For mikrotik, you can get 8x sfp+ ports for about twice the cost of this switch, then you've got to pay for the tranceivers you want. There's also the question of if existing cabling will work for 10G vs 2.5G, recabling is not realistic for most.

bpye 4y ago
If you only need a couple 10G-BaseT ports you can get 10G SFP+ modules which in my experience work well enough. They do get quite hot, but I only needed 10G-BaseT for my desktop whilst everything else at 10G is DAC.
- AdrianB1 4y ago
  I am on 10 Gbps is parts of my house for a while, 10G on UTP consumes a lot of power and you cannot realistically fill a SFP+ switch with RJ45 transceivers because of that; they are also very expensive for what they provide. At the same time, a SFP+ NIC and a DAC or AOC cable is a lot cheaper and low power. In most cases existing cabling is CAT 5e, you can run 2.5 Gbps with no problem, while 10 G requires re-cabling. This is practically the reason 2.5 Gbps exists: it is the limit of existing Cat 5e infrastructure, just put a switch and you're done.