QSFP and link aggregation

[timbaker]

Hello experts,

I'm trying to work out how QSFP ports can be used in Meraki MS355 switches and can't find much about it in the documentation.  More specifically:

1) Does the MS355 support "octopus" 4 x LC to 1 x QSFP+ breakout cables?

2) If I connect 4 x 1Gbps to a QSFP+ port, will the MS355 see this as 1 x 4Gbps or 4 x 1Gbps interfaces?  (If 4x1 can I use LACP?)

3) Can I connect, say, 3 x 1Gbps to a QSFP+ port?  Or must all 4 channels be used?

4) If I have multiple links going into a QSFP port via octopus cable and one link goes down, what happens at the switch interface?  

For context... I have 10Gbps uplink and want to aggregate 1Gbps links to provide a redundant uplink > 1Gbps.  But in several cases I only have 6 fibre cores (ie: 3 x 1Gbps) and in other cases if I use SFP ports and LACP I'll run out of SFP ports. Hence the questions above...

Can anyone help shed some light on this?

Thanks!

[GIdenJoe · Accepted solution]

Hi Tim,

This question has arisen a few times on this board and the answer always is that there is no support for breakout cables.  So the interfaces on MS switches cannot be split up.  So most of your questions will be answered with a hard no.

If you have six fiber cores, then you have 3 pairs so you can have at least 2 uplinks.
Is there no way you can use your 10G uplinks instead towards you core switching?
You can ofcourse also use 40G BiDi transceivers if the fiber is less than 100m and your core has 40G ports but the first seems more realistic.

[timbaker]

The 1 and 10 Gb uplinks provide diverse physical paths, hence the preference for including the 1's (preferably aggregated).  

Thanks for the quick response.