Ring Fabric; Ring Fabric - HP StorageWorks 64 - SAN Director Switch Planning Manual

Ring Fabric

A ring fabric consists of a continuous string of directors or switches connected by
one or more ISLs. Each fabric element is connected to the next fabric element
(like a cascaded fabric, but with the end-point fabric elements connected).
Figure 37
Figure 37: Ring fabric
Ring fabrics are generally more expensive than cascaded fabrics, are also easy to
deploy, provide a simple solution to add additional fabric devices, and can solve
hop-count problems inherent to cascaded fabrics. Ring fabrics also have increased
reliability because traffic can route around a single ISL, director, or switch failure
(subject to hop count limitations).
Like cascaded fabrics, ring fabrics are well suited for applications where data
access is local, but not for applications that require any-to-any connectivity. In
addition, ring fabrics are useful when connecting SANs over a MAN or WAN.
These networks typically use a ring topology.
SAN High Availability Planning Guide
illustrates a ring fabric topology.
TM
PWR
ERR
TM
Interswitch Link
Fabric Connection
Planning Considerations for Fibre Channel Topologies
31 29 27
25 23 21 TM
19 17 15
30 28 13 11
26 24 22 9 7 5
PWR ERR 20 18 16 3 1
14 12 10 PWR
8 6 ERR
4 2 0
91