Hallo,
Maybe anybody knows how to enable (if possible) Jumbo Frames on CRS317-1G-16S+RM with S+RJ10 modules? I changed MTU and M2LTU on 9014 but packets bigger then 1500 are dropped. With standard SFP+ fiber modules jumbo frames works fine. Tested ROS 6.40.6 (bugfix) and 6.41.3 (current) - no differences. MTU displayed 9014, max MTU supported 1500 !!. Did S+RJ10 not serve jumbo frames?

Curious? No answer from MikroTik technicians yet? Every manufacturer, even cheap hardware at 1Gbps, boasts of the jumbo frames. For 10Gbps this is a must have function. I browsed technical informations about S+RJ10. No info about jumbo frames: https://mikrotik.com/product/s_rj10
What is the purpose of making the SFP + insert without jumbo frames service?
All I need is just one simple answer: YES it supports or NO it does not support, or it will be able to handle this after upgrading the software/firmware.

I would like some information about this missing jumbo frame support too.

When I first got these modules I did some extensive testing, and found out that every time the mtu was beyond the standard internet 1500, it would
start to run very slow (until path mtu found out the lower mtu was needed)..

So for internet usage they might work fine, but for any serious datacenter or server application it has to support higher mtu (jumbo frames).

The module appear to use the Marvell 88X3310P chip, but have been unable to find any information about mtu in the chip documentation.

Can add the module has the same burst problem/buffer problem (slow throughput) as the CRS328 switches 10G to 1G ports, when the link rate of the module is lower than the sfp+ (10G) rate.
Hope it can be fixed by some kind of software/firmware upgrade, and it isn't some kind of hw. limitation.

I tried the same with two S+RJ10 modules per switch and found the following:

2x CRS317-24G-2S+ with 2x S+RJ10

both switches have a minimal configuration: bridge with all RJ45 and SFP Ports, HW Offloading, MTU = 9000

Switch1 is connected with Switch2 via SFP1 on both devices. Two workstations are connected via SFP2, both with the ASUS XG-C100C 10 GbE NIC. If the MTU for every device and NIC is set to 9000, there will be no connection between both workstations - but: each workstation is able to ping the switch they are connected to.

Is the limit exactly 1500? I don't need to pass big (9k) jumbo frames, but need VLAN tags (single ones, not QinQ) and extra 8 bytes for RFC4638 PPPoE traffic, this means minimum L2MTU of 1526 (1514 for standard Ethernet + 8 for RFC4638 + 4 for VLAN). If existing cat5e cables can't be used with S+RJ10 at 2.5 or 5 Gbps, I will have to run some fiber and use fiber SFP+ modules instead.

As for "each workstation is able to ping the switch" - with what maximum ping size?

Oh god, good to know I almost bought it for NAS connection where 9k jumbo is mandatory.

According to Mikrotik support the S+RJ10 modules 'currently' do NOT Support Jumbo Frames.
However, i did not get any answer if this as firmware/software limitation and might change in the future or if this a permanent hardware limitation.

According to Mikrotik support the S+RJ10 modules 'currently' do NOT Support Jumbo Frames.
However, i did not get any answer if this as firmware/software limitation and might change in the future or if this a permanent hardware limitation.

Can you even hypothetically upgrade SFP module firmware?... it sounds like upgrading pendrive firmware. Never heard of that aside from hacking vulnerable chips.

anything changed in this topic? I'm in urge to get 10G routing with CCR1009 but I'm afraid it won't handle 10G on single connection (single core) without jumbo.

+1, why would jumbo frames not be supported on a 10G capable interface....

+1, why would jumbo frames not be supported on a 10G capable interface....

On the other hand... Name me one 10G copper SFP+ module other than mikrotik for 65$ brand new. Go on. I tried xD
Until MikroTik saves us, 10G copper still costs kidney. Currently they saved us in 50% because no jumbo I bit the bullet and decided that jumbo support is not worth additional 120$ which is around price difference to next cheapest 10G copper module I could find. Though CCR1009 is dying without jumbo.