Estimates for data center network bandwidth usage?

[chuckk281]

Paulo had a question:

When we don’t have any data concerning the current Data Center network usage, what kind of reasonable assumptions must be defined ? Does anyone have some kind of report ( or at least tips ) regarding the typical bandwidth consumption on Physical and Virtual Machines so we can design the network of a medium size Data Center ( < 1000 servers ) ?

Erik replied:

This is what I reference / suggested when planning a network for virtualized systems without any network data.

Source: http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01608922/c01608922.pdf page 3, table 1

Network	Data Traffic	Bandwidth
Communication - Non performance critical IP-based communication, primary client server communication (public network).	Email, file sharing, web services, streaming media, SAP GUI	1 Gb1
Management –Performance critical IP-based communication, primary administrative and server management communication.	Console OS to manage physical server and/or virtual machines, and virtual machine migration (such as VMotion)	2 Gb
Computing – Inter-Process Communication (IPC) like SAP application server to SAP database or central instance communication (private network)	Cluster communications, Virtual machine (VM) or SAP application server traffic (production)	4 Gb
Storage – All data communication to and from storage systems	NAS, iSCSI or backup traffic	2 – 4 Gb

Anyone else have a good rule of thumb?