Setup Trunking between multiple switches

[slewfoot2xm]

Current setup:  E3800  2 port Link AGG to 1910-48

I would like to add another 1910-48 to work in parrelll with the current one (IE I'm running out of ports)

i'd like it setup so that the e3800, still has it's Link AGG to the existing 1910-48 , and then add another Link AGG to the new 1910-48.   I would also like to have the existing and the new 1910-48 Link AGG'd to each other so that i'm not sending traffic through thier uplinks to the e3800 for what needs to cross them. 

Is there a way to setup the Link Agg between all 3 and not create a Loop? 

[parnassus]

If you rely only on LAGs uplinks (or just simple single link uplinks) between your three units the loop is granted for sure [*] both physically and logically.

A possibe way to avoid a logical loop by permitting a physical loop to exist is to rely also on MSTP...so for some involved VLANs the logical path would be possible through a daisy chain physical path - instead of a loop - involving A<=>B<=>C (the logical link between C<-->A will be blocked despite it still exists physically C<=>A) and, for others VLANs, the respective logical path will be possible through a daisy chain physical path - instead of a loop - involving A<=>C<=>B (the logical link between B<-->C will be blocked despite it still exists physically B<=>C).

[*] To be clear: if LAGs are, respectively, configured between A (your center Switch E3800) and B (existing Switch OfficeConnect 1910) and between A and C (added OfficeConnect 1910)...there should be no problems (no physical loop -> no logical loop even if MSTP is not adopted).