[c-nsp] 720-3BXL IOS 15

[Curtis Piehler]

Does anyone have any suggested 15.x Versions for the 720-3BXL Cards?  I
have a couple of 7606 routers that have a need to run BFD + BGP within a
VRF Instance.  The current 12.2(33)SRB3 does not allow this.

The router takes in 3 full copies of the Internet routing table as well as
some very light VPNv4 routing tables.  I've already reallocated the TCAM to
allow 768k IPv4 Routes.

Thanks