So the consultant from the inks company phoned again, and needs a little help. Seems that the HP JetDirect printing to some of their sites has broken, since the transition to the new network.
A bit of a look, and some disabling and re-enabling some functions later, and we get back to everything working for a site connected via an IPSec VPN link, with no overall changes.. but now it works.
For the other site, we have an issue that might have been a TCP MSS size problem (connections starts, but fails to transfer data). Fudged the juniper WX devices with a lower MSS size for accelerated traffic but no dice. It appeared as if the hard disk was busy, which the disk based compression engine uses. So removed the traffic out of NSC, but again no dice. Disabled tcp acceleration, and everything's hunky-dory..
The only part of the network which previously had Junipers at both ends were the data centres. ThisĀ link uses the other providers connections and these were devices were previously customer managed. So MSS for this link would (should) be consistent at both ends. I'm still certain that they fudge the MTU on their network in someway. Even though the changes to MSS should have dropped the packet size to avoid this. Still another case to open with JTAC. At least we have full traces and diag files for this one.