Are you at the point where you need to update the old Cisco Catalyst 6509s in the core of your data center? If you are, you’re probably looking at the Nexus line of data center switches that Cisco has been promoting for the last couple years. Many enterprises are trying to decide whether to migrate from Catalyst to Nexus or to look at Cisco alternatives — either one of the newly risen big guys like Juniper and HP Networking or some of the long time data center networking specialists like Force10 or Brocade (formerly Foundry).
Jeremy Filliben, CCIE @3851 just blogged about his experience in migrating from Catalyst to Nexus in his data center. Basically he built a new Nexus LAN, with dual Nexus 7010s in his core, alongside his legacy Catalyst LAN and interconnected them before cutting over the Layer 3 Functionality in his network from his old core Catalyst 6509s to his new Nexus 7010s.
Jeremy goes into detail about the problems he’s encountered during this project, including some glitches with extranet BGP peering and spanning tree root migration. The BGP issue was caused by a overlapping third-party BGP Autonomous System (AS) numbers, which in Catalyst he had always handled by enabling the “allowas-in” knob on his internal routers. The feature isn’t available on Nexus yet. He traced the spanning tree issue to the fact that Nexus switches handle Bridge Protocol Data Units (BPDUs) in a way that is different from how Catalyst handles them. The issue will force him to keep the Catalyst 6509s in production longer than he wanted. Check out his blog about the Catalyst-Nexus migration to find out how he fixed these issues and learn about some other minor but annoying things he has discovered during the project.
Jeremy also pointed out a nice resource by Carole Warner Reece on her blog at Chesapeake Netcraftsmen which provides side-by-side comparison of the differences between IOS and NX-OS command line interface.