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Technology Stocks : The New QLogic (ANCR) -- Ignore unavailable to you. Want to Upgrade?

To: THOMAS GOODRICH who wrote (20669)	2/9/1999 6:42:00 PM
From: Greg Hull	Read Replies (2) \| Respond to of 29386

To All: In an effort to learn more about more about MIBs and public/private loops, I read the SAN white paper available at the Hitachi Data Systems site: hds.com I would be very appreciative of comments to correct any misimpressions I may be demonstrating with the following summary of the paper. 1. FC features a 2112 byte payload if the optional header is not employed or a 2048 byte payload if the optional header is employed. 2. The optional header contains the WorldWide Name, a 64 bit entity consisting of a 24 bit company name assigned by the IEEE, 36 bit vendor-specified identifier, and a 4 bit format ID. 3. Switches store the WW Names in a Simple Name Server table during Fabric Login 4. Hubs and FC-AL loops do not record WW Names, but instead each node records the relative address of each other node on the loop (Loop Initialization or LIP). If a node is added or deleted, the loop must undergo another LIP. 5. Tape storage devices should usually be kept off FC-AL loops. 6. The practical limit is 5-8 disk drives per loop. 7. Switched fabrics do not need to be reconfigured if a node is added or deleted since the switch stores the addresses, rather than each node (Host Bus Adapter) in the case of loops. 8. Loops can be attached to switches. If the attaching node supports Fabric Login it can be a Public Loop. If the attaching node does not support Fabric Login it must be a Private Loop. 9. Private Loops cannot communicate with a node off its loop. Public Loops can access any other node in the fabric (switch). 10. Brocade has a translative mode that creates a pseudo WW Name for loops that do not support Fabric Login. This allows the private loop to function as a public loop. 11. NT hosts assume that every device on its loop belongs to it, and therefore expects non-compliant devices to be reformatted. 12. Zoning is required in a switch to separate NT nodes from UNIX storage drives. 13. Standard Management Information Blocks (MIBs) have not been defined for hubs or FL ports on a switch. (I assume this is what the FibreAlliance is attempting to standardize.) Please correct any errors I have made above, or expand the implications if possible. What are the functional differences between software zoning and hardware zoning, and how do Brocade and Ancor differ on support for Public Loop. Thank you for the help. Greg