Me neither...
This is from the quickspecs:
7506:
Throughput 488 million pps
Routing/Switching capacity 768 Gbps
Routing table size 256000 entries (IPv4), 8000 entries (IPv6)
MAC address table size 512000 entries
And along with this info from the datasheet:
VLAN
Supports up to 4,096 port-based or IEEE 802.1Q-based VLANs; and supports MAC-based VLANs, protocol-based VLANs, and IP-subnet-based VLANs for added flexibility
I would expect it to be able to setup 4096 ip interfaces. Specially since 7500 is in the upper series. I know that 5120 series can do 32 or so ip interfaces and 5820 recently updated from 49 to 400 SubIP interfaces (note that this is regarding sub-interfaces, not primary interfaces). I would expect that 5820 would be able to create 4096 ip interfaces aswell...
Unfortunately HP isnt very clear on this subject, somebody else who might know if there exist some kind of "performance matrix" where this is pointed out how many ip interfaces each model can setup concurrently (along with routing between them)?