Switch recommendations needed

[thoth bravely]

Hi,
I am by no means a network engineer, so I'm hoping I can provide my use case and get some constructive feedback and a specific make/model of switch to buy.

So I am currently running my main servers, NASs and workstations over 10GBE with jumbo frames. They all work great and I don't want to change anything there. I have my 10GBE switch hooked up to a 1GBE layer 2 switch (a netgear JGS516PE, the one I am looking to replace). That switch runs wired connections to all non-10GBE devices (still using jumbo frames), but also runs wired connections to powerline adapters into other rooms, to wifi access points and to some devices that don't support jumbo frames (raspberry pi, etc.), which -- obviously -- is causing problems. So basically, I'm looking for a layer 3 1gbit switch that handles port-specific mtu settings and will fragment IP packets to fit those mtu windows (do all layer 3 switches do this? I don't know). It also needs to support VLANs. I've walked into supposedly tech savvy retail stores and get a lot of nothing for responses. I don't want to drop a grand on a switch just to get it home and find it's not what I need. I don't think are uncommon issues, so hopefully someone more knowledgeable can chime in.

Thanks,

thoth

 

[Spartacus]

I'm not a networking expert either, I know many L3 switches support jumbo frames but to get port specific mtu settings you likely need to look at enterprise grade like Cisco (which can be had pretty cheaply with older used equipment <$150).
My unifi switch has the ability to do vlans and turn on jumbo frames (which should work up to 9000MTU and auto set for anything lower) but you cant manually set it on a per port basis its all or nothing (at least from the gui) it looks like there are CLI options for individual port MTU setting that don't persist through restarts.

 

[fohdeesha]

all the expensive enterprise switches I've ever used kick fragmented packets to the CPU to handle fragmenting, eg it's SLOW. This is because fragmentation should basically never happen in a properly designed network, so handling it isn't exactly a top priority.

Sending data across a path with differing MTUs should be detected and automatically fixed (eg, use lowest common MTU) by the device by using PMTUD - however as you've noticed a lot of devices and software do not implement PMTUD properly if at all, so you end up with software stacks trying to send 9000 byte packets across a link with an MTU of 1500.

This is one of about a billion reasons I don't recommend people use jumbo frames unless you have incredibly specific requirements, or huge links (40gbE+). On a variety of older hardware I haven't seen jumbo frames actually increase throughput in several years - hell, I can get ~35gbps on R720 gen hardware at 1500mtu

 

[thoth bravely]

thanks for these replies... very helpful.