Are you sure that the HP blade switch only supports MSTP?
http://h20000.www2.hp.com/bizsupport/TechSupport/CoreRedirect.jsp?redirectReason=DocIndexPDF&prodSeriesId=1845925&targetPage=http%3A%2F%2Fbizsupport1.austin.hp.com%2Fbc%2Fdocs%2Fsupport%2FSupportManual%2Fc02261902%2Fc02261902.pdf
"mode {rstp | mstp | pvrst}"
With non-Cisco devices, the interesting part is always Cisco's per-VLAN implementation.
If a trunk is formed by a Cisco switch,
- they send untagged BPDUs to the IEEE destination MAC 01:80:C2:00:00:00
- they ALSO send untagged BPDUs with Cisco proprietary destination MAC 01:00:0C:CC:CD
- and for every tagged VLAN they send tagged BPDUs with Cisco proprietary destination MAC 01:00:0C:CC:CD
A non-Cisco device normally won't recognize frames with destination01:00:0C:CC:CD as BPDUs, but because the I/G-bit is set to Group, the frame has to be treated as multicast. So this proprietary BPDUs will be flooded over all ports, except the port it was originally received.
So, depending on you topology, the per-VLAN BPDUs will be "relayed" to the connected Cisco switch(es) and normally here some ports will be blocked in order to prevent bridging loops.
If rapid transition (proposal/agreement) works for the per-VLAN instances also will depend on your topoloy. Otherwise you have to wait for timers like the original STP (Listening, Learning).
Hope that helps.
Best regards
Rolf
