If you missed my last post, I discussed the various differences between the category of products that Cisco refers to as "Fabric Extender" or FEX.
Cisco Nexus Rack Fabric Extenders
Now, being only a FE/GE switch, you would be tempted to thing that its gigabit performance might be surely outpaced by the newer 1/10GE FEXes . . . and you would be correct in many circumstances. But the 2248TP-E is more of a purpose-built switch for particular workload characteristics:
The Cisco Nexus 2248TP-E Fabric Extender (FEX) is optimized for specialized data center workloads, such as Big Data, distributed storage, and video editing, in scalable 100 MB and 1 Gigabit Ethernet environments. It features a large buffer space that is designed to sustain bursty applications. — Cisco.com
- iSCSI (1Gbps—yes lots of companies still run this!)
- Backup Applications/Network
- Video Streaming Repositories (such as security camera archives or video libraries)
- Audio Streaming Repositories (such as call recordings or audio libraries)
- And of course . . . Big Data
The 2248TP-E mitigates this by having a full 32MB buffer available to any number of ports on the switch; it is fully configurable. I can dedicated some bandwidth to some ports, or mix and match how I choose. In my experience, most deployments leave the configuration the default of 32MB shared, and let the Nexus dynamically allocate buffer space as required.
Enhanced Drop Counters: instead of a generic "drop" counter, the 2248TP-E has NIF-to-HIF and HIF-NIF differentiated counters (read more about Network (NIF) and Host (HIF) ports). Additionally, because of the larger shared buffer, there is a very helpful "drop due to no buffer" counter.
This enhanced buffer drop counter is very nice; otherwise, you are left to look at something like this generic message:
Finally, there are two other enhanced drop counters:
- MAC error drop
- Truncation drop (shown as MAC error) – Multicast drop