5300xl switch not handling downstream loops

[IShall]

Hello,

At one of our sites, we have a pair of 5308xl switches, linked by a pair of aggregrated 1Gb links, acting as the core.

Someone looped two ports on a directly connected 1810G switch. Result ? Port on 5308xl was blocked by spanning-tree, as expected. However, whole network across both core switches pretty much ground to a halt, until the blocked port was actually disabled (I have now put loop-detection on all ports).

Question, if the port was correctly blocked, and "broadcast-limit" was enabled on both 5308xls, then why did the network take such a hit ? My understanding of the global "broadcast-limit" command is that broadcast/multicast traffic limits individual port traffic to1000pkts/sec, so is it the case that the 5308xl is simply unable to process this load ?

Anyone else had a similar experience ?