Paul, there is no way to resolve the issue. Cisco recommended that I route IPX via a separate device that switches IPX L3 in hardware, like a 7200 series. With 12.1.13 IOS release, we're supposedly getting 80Kpps IPX forwarding rate. For the most part, the users aren't feeling the impact of this - as long as Netware Core Protocol lights up packet bursting, we're fine. The first packet of an NCP burst takes 11-15ms across a gigabit link between 2 4507's, but the subsequent packets in the burst arrive in sub-1ms times. An NCP burst ACK from a client will take 11-15ms again. Overall, it's not a big deal in that scenario, so file access and printing from the Netware servers we're phasing out isn't too bad. We're feeling the pain with MS Access. Users have MS Access MDB files living on Netware servers. For whatever reason, client access to MDB files won't packet burst. It's still NCP back and forth, but the application bundles packets so inefficiently that we were seeing 1, 2, 10, etc. bytes in the data payload, with bursting never starting up. Users were screaming about how slow their wretched little MS Access applications were going. The only way to fix that issue was to bring the application to the same L2 network.
My advice is that if you have a long-term committment to IPX (we do not), don't buy a 4507. That said, I love everything else about this chassis. IP performance is outstanding. The stability and uptime has been 100% - I had a out-of-box failed Supervisor 4 engine, and a fan tray recall replacement, but other than those growing pains you expect with a newly released product, the chassis has been a flawless performer. We replaced 3 Enterasys SSR chassis with the 4507's, and I don't regret it for a second. The SSR boxes had all sorts of routing table and OS stability woes, plus couldn't recover from a power failure on their own. The 4507's have made our life easier in every regard except IPX L3 performance...since IPX is going away here, that's a pill we can swallow easily.
