Hi all.
I have to connect two switches to one router. I am a bit unsure which of the following three options would be the best in terms of performance. Can you kindly advise, please? Many thanks.
…I’d use Option 3+, using a 10G AOP/Fiber connection between CRS326 and RB4011 instead of a 2x1G bond.
According to the block diagram of the RB4001, each Switch Chip is connected to CPU with a 2.5G Link…SFP+ with 10G, with max-out because of CPU with approx 6-7Gbps.
This would be the best of all worlds, as connections between CRS112 and CRS326 would not necessarily hit the RB4011 CPU (in an inter-vlan scenario, you could even upgrade to L3-HW-Offloading on the CRS326 with ROSv7.1rc) and you’ll end up with max bandwidth to the RB4011, which is better than 2-4x1Gbps from your other options.
As the CRS326 and CRS112 both have at least 2 SFP+ ports, I’d also connect the CRS112 to the CRS326 using a 10G link, either fibre or DAC if the distance is very short.
Hi all.
Thanks for opening my eyes… 
Haven’t had thought about using SFP+ connectivity between the CRSs & the RB4011 at all. According to https://wiki.mikrotik.com/wiki/MikroTik_wired_interface_compatibility all three devices should support https://mikrotik.com/product/xs_da0001. I’ll remove the bonding and use just single links utilizing XS+DA0001.
The 6..7 Gbps of the RB4011 should be fine, I am running just a small home office with two or three APs connected to the CRS112 (due to the PoE option). Most of the load will stay on the CRS326 (NASs; a few PCs; a printer).
Again, many thanks for your time. Have a good rest of your day.
SFPs is a better solution indeed.
Also, notice that only CRS3xx devices are capable of using bonding Modes without losing the Hardware Offload on the Bridge, and those modes are 802.3ad and XoR modes…
So if you did use bonding between those devices you would ofcorse loose the Hardware offload feature.
If you need redundancy you can ofcorse connect those devices additionally with an ethernet port as well using the RSTP features…
IMHO CRS112 has 4xSFP, hence 1G, not 10G.
Please check again…IMHO the RB4011 will not offically support DAC (copper), but rather needs an AOP or “real” fiber tranceiver. I use this one: https://www.fs.com/uk/products/74607.html?attribute=1511&id=196567
Your comment made me a bit nervous… 
I’ve checked and came to the conclusion that according to MikroTik XS+DA0001 is supported on RB4011:
I hope, I can trust this compatibility list… 
Anyway, I made a note about the alternative solution you proposed. Many thanks.
Yes, you can,
Actually when I bought my RB4011 the XS+DA0001 was not available in the market, only the S-DA0001, which would not work.
Sorry for the confusion.