BPDU forwarding priority with QinQ

[msundman]

First, in a normal switching environment, when a procurve switch generates control packets like BPDU, what QoS output queue does it put these packets in, and what happens if that Tx buffer is full? Does it somehow "make room" for it, or does it discard that packet?

Next in a QinQ environment with Procuve 5406 switches, how is control packets (STP BPDUs, OSPF etc) from Client VLANs handeled when forwarded to a congested S-VLAN link? Just like any other traffic? So on a congested link, a clients OSPF or STP packets might very well be discarded?

The reason for asking is that we recently had an incident with a customer whos STP and OSPF topology broke down on a link consisting of two 5406 QinQ switches and the only trace of a problem in the Procurve switches are a lot of logged "Tx Drops" on the link during the outage.

If control packets in fact ARE forwarded just like any other traffic, what is best pratise to solve the problem to ensure such traffic always is forwarded with highest priority?