VSAN / FCoE and NPV - when to use which?

[Grex Nor]

Hi,

I'm kind of new to Datacenter and trying to catch up, one thing I don't really grasp is when to use what, trying to read configuration examples and google around but, maybe it's just me, but it's hard to find any really good ground examples and sadly you can't really do MDS / FCoE labs with VIRL, and have to rent rack's from, say, INE.

Well, to my questions, I understand that you use VSAN to connect storage, and is this only something you do in Cisco MDS (on Cisco)?
When do you really use FCoE is it just to connect LAN clients to your VSAN, do you then more or less always have to use FCoE to have your ethernet client access your VSAN?

And do you configure NPV just to have a switch act like a proxy to your VSAN? When you do a "show npv status" is the external interface the interfaces facing the other switch/equipment?

Would be grateful if someone could explain the above!

THANKS!

[Manish Gogna · Accepted solution]

Hi Grex,

VSANs have the same purpose as VLANs, it is a Cisco proprietary feature.

VSANs isolate servers and storage devices that are physically connected to the same fabric, therefore allowing creating of logical SAN islands on a shared hardware. Each VSAN effectively functions as a separate SAN. 

Each VSAN has its own fabric services completely isolated from fabric services in other VSANs. For instance: FCID Domain Manager, FCNS Name Server, FSPF, Zoning, Port Security database. Fabric Events are isolvated per-VSAN basis.

Yes, they are configured on MDS switches as detailed in one of the CLI guides below

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/mds9000/sw/4_1/configuration/guides/cli_4_1/clibook/vsan.html#pgfId-1089123

With FCoE, network (IP) and storage (SAN) data traffic can be consolidated using a single network. This consolidation can:

• reduce the number of network interface cards required to connect to disparate storage and IP networks
• reduce the number of cables and switches
• reduce power and cooling costs

Computers can connect to FCoE with converged network adapters (CNAs), which contain both Fibre Channel host bus adapter (HBA) and Ethernet network interface controller (NIC) functionality on the same physical card. CNAs have one or more physical Ethernet ports. FCoE encapsulation can be done in software with a conventional Ethernet network interface card

In NPV mode, the edge switch relays all traffic to the core switch, which provides the Fibre Channel switching capabilities. The edge switch shares the domain ID of the core switch.

The core switch provides F port functionality (such as login and port security) and all the Fibre Channel switching capabilities. The edge switch appears as a Fibre Channel host to the core switch and as a regular Fibre Channel switch to its connected devices.

There are some good videos on youtube that you may check to gain better insight into these.

Manish

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[Grex Nor]

Thank you Manish!!

So, FCoE is a nice feature which make it easier and more cost efficient to connect to your lan?
You must not use it to have your client reach the SAN.

Don't quite get how a CNAs card then helps connect to the lan, since you have it on your server don't you connect both sfp ports on it to your MDS, do you need two ports to separate the traffic, and it just a for ILO and other VSAN traffic to your MDS?

Did you know if:

When you do a "show npv status" is the external interface the interfaces facing the other switch/equipment?

Thanks for taking your time helping me!

[Manish Gogna]

Hi Grex,

Figure 2 of the following doc shows the change in network design before and after implementing FCoE and it details the various benefits of this feature

https://www.cisco.com/en/US/solutions/collateral/ns340/ns517/ns224/ns945/ns1060/at_a_glance_c45-578384.pdf

Yes, the output of the show npv status command is used to display the status and VSAN membership of the different servers and external interfaces.

Manish

[Grex Nor]

Perfect, thanks!

And again - thanks for taking the time to help me out!!