Anish, On Oct 18, 2011, at 1:30 PM, Anish Bhatt wrote:
> Mark, > I was reading up on some previous correspondence regarding how > iSCSI traffic should be sent via a separate VLAN. I'm trying to figure > out the use case for said scenario. Is the idea that iscsi traffic is > run over a separate VLAN interface (created using the VLAN id from the > VLAN header for iSCSI configured on the switch) but with the priority > group pulled from DCBX ? The set_dcb_priority() calls upstream seem to > suggest this approach. Or were u suggesting that open-iscsi create some > sort of internal VLAN for explicit DCB use ? > -Anish > > One socket to bind them all. The reason to use a VLAN is to have a VLAN tag that can indicate the priority as packets pass through switches. iSCSI should then be using that VLAN interface for its traffic. You will see that the DCB code gets the desired priority from the app TLV provided for the underlying link interface. If the iSCSI traffic were not sent to the VLAN interface, the priority would only have meaning within the system. That is, the priority could still affect the queuing within the system, but without the VLAN tag, it would not be able to represent that priority over the wire to other devices in the network. If, for whatever reason, there is no need to indicate that priority to other network devices, then it would not be necessary to to have iSCSI use a VLAN. A VLAN that only existed internally would defeat the purpose of having the VLAN tag indicate the priority of the traffic to other devices. Again, if indicating the priority over the wire is not important, then this could be done, but an internal-only VLAN would seem to serve to purpose at all. The link device could just as well be used if there is no need to communicate that priority to other devices. I don't think that there is any need for open-iscsi to create any special VLAN device. >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] >> On Behalf Of Rustad, Mark D >> Sent: Friday, October 07, 2011 2:35 PM >> To: [email protected]; Anish Bhatt >> Cc: [email protected] >> Subject: Re: Add initial DCB support >> >> Anish, >> >> On Oct 7, 2011, at 1:47 PM, Anish Bhatt wrote: >> >>> Bringing up an old discussion for clarification here. If I > understand >>> correctly iscsi tlvs will be exchanged with protocol id set to >>> 3260(0xCBC) at all times, and this will get mapped to the correct >> iscsi >>> traffic flow at the endpoint irrespective of actual running port >> number. >>> Is that correct ? >>> -Anish >> >> Yes. The port number used in the tlv identifies the application by its >> well-known port number, but the application can still be configured to >> use whatever port it wants. >> >> -- >> Mark Rustad, LAN Access Division, Intel Corporation -- Mark Rustad, LAN Access Division, Intel Corporation -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
