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Occasional Contributor
ramachandran.lakshminarayanan
Posts: 7
Registered: ‎03-08-2012

When WWN of port is used ?.

Hello All,

We are using soft zoning(WWPN) for device communication and DCFM for managing DCX switches .seeing device details,i could see wwn starting with 20xxxxxxxxxxxxxx address for particular port. I dont see its used anywhere for communication purpose.I could understand its like MAC address for that particular port but i dont know in which situation it will be useful ? Where it can be useful ?.Whether using WWN we can perform zoning ? .What its advantage when WWPN is available ?...Please help me out with examples .

Thanks,

Ramachandran L

Contributor
sebastian.thaele
Posts: 60
Registered: ‎05-26-2009

Re: When WWN of port is used ?.

Hi,

There is no soft zoning anymore. That was long long ago. WWPN is hard zoning (frames with destination addresses not zoned with the source device will never reach the destination device) and it's also hardware zoning (done in the ASIC without CPU involvement). WWPNs are not a feature you can choose to use in the communication. They will be used. A device has a fixed WWPN (forget about FA-WWNs at the moment) and it will use that WWPN for the login into the fabric (FLOGI). Then it will get its 24bit fibre channel address which will be used in the FC header of all subsequent frames. Beside of that it will also use it as an identifier for the nameserver and for upper layer protocols. For example most of the storage controllers map the LUNs to specific WWPN to avoid unintended access of the wrong host to the LUNs. Or on the host itself the WWPN is often used as a part of the identifier for a path in the multipather.

When you speak solely about zoning, then there is Domain,Port and WWPN zoning. Both are hard zoning, both are hardware zoning. Domain,port has the advantage that you can replace an HBA (and get another WWPN) without re-zoning. WWPN zoning has the advantage that you can re-cable devices on different ports without re-zoning. For small switches with only a few ports domain,port zoning might be sufficient, but usually medium to big installations are zoned using WWPNs. For both variants you can use aliases, which helps a lot to keep the overview. In addition some features just need WWPN zoning to work, like FC routing, QoS, TI-Zones, etc.

Occasional Contributor
ramachandran.lakshminarayanan
Posts: 7
Registered: ‎03-08-2012

Re: When WWN of port is used ?.

Hi Sebastian,

I guess you are trying to say Hard zoning is not anymore ,because WWPN zoning is also called as soft zoning where as port based zoning is called hard zoning . My question is what is use of WWN of port not WWPN ?. When it is used ?..

Thanks,

Ramachandran L

Contributor
sebastian.thaele
Posts: 60
Registered: ‎05-26-2009

Re: When WWN of port is used ?.

Hi Ramachandran,

No, that's not what I wanted to say. Where did you get the info from that "Hard zoning is not anymore" and "WWPN zoning is also called as soft zoning"?

Plus "WWN of port" equals WWPN. WWPN means Worldwide Port Name.

I already wrote above when it's used. Please have a look in my first answer.

Cheers seb

Occasional Contributor
ramachandran.lakshminarayanan
Posts: 7
Registered: ‎03-08-2012

Re: When WWN of port is used ?.

Hello Sebastian,

In first line you have mentioned "There is no  soft zoning anymore" . I dont understand what that mean actually ?.So far i have learnt that zone members which contains WWPN's of end device is softzoning and zone members which contains switch port numbers,domain is called hard zoning .As well WWN of port is different than WWPN which we use in zone members.Can you please clarify and correct me if i am wrong

Thanks,

Ramachandran L

Contributor
sebastian.thaele
Posts: 60
Registered: ‎05-26-2009

Re: When WWN of port is used ?.

Hi Ramachandran,

It means that "soft zoning" was a concept used in the first switches. It had for example the following behavior: When an initiator logs in a switch, it queried the name server for its targets. The switch told the initiator which targets it can reach based on the zoning. But if the initiator decides to send a frame to another valid address it was not zoned too, the frame actually reached that un-zoned device. (It could have been a old address it was zoned to once or it could have the address from a query to the switch's management server.) For some years now, Brocade switches don't use this mode of operation anymore.

In the current admin guide Brocade calls its mode of operation "hardware-enforced". It will not send the frame to a destination device which is not zoned with the source device. And it will be used whether you use domain,port zoning or WWN zoning.

If you mean the WWN of the switch port itself (not the WWN of the device port) than you don't have to care about that in the zoning. It's only used for the communication between switches. So you'll see it for example in the fabric show. But most of the time it's not relevant.

Cheers seb

Occasional Contributor
ramachandran.lakshminarayanan
Posts: 7
Registered: ‎03-08-2012

Re: When WWN of port is used ?.

Hello Sebastian,

Excellent explanation from you.

Now you got my question well ,i am asking about WWN of the switch port only .I dont see it used anywhere . It would be appreciated ,if you explain me in which scenario its used for communication between switches .

Thanks,

Ramachandran L

Frequent Contributor
Grace.Chang
Posts: 177
Registered: ‎02-14-2011

Re: When WWN of port is used ?.

Hi ,

Glad that you got your question answered! I have moved your discussion thread to the Data Center SAN Forum as that will be the best place for you and others users to find this particular discussion thread. This forum is for non-product related questions.

Thank you for using Brocade Communities!

Cheers,

Grace Chang

Global Community Manager

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