Dell PowerVault 51F Dell PowerVault 51F 8-Port Fibre Channel Switch Insta - Page 47

PowerVault 51F Topologies, Fabric Elements, Routing Cost

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FILE LOCATION: S:\SYSTEMS\Boxer\rev_i&t\English\50UWDa00\50UWDc20.fm CHAPTER 2 PowerVault 51F Topologies support.dell.com This chapter discusses some key factors affecting fabric performance, including the following: • Fabric elements • Sample fabric topologies Fabric Elements Each fabric is unique and the elements that determine the fabric's structure include: • Class of frames in the fabric • Type of host adapters connected to the fabric • Bandwidth requirements supported by the fabric • Topology of the switches in the fabric • Requirements for redundancy and fault tolerance Regardless of the topology used, the switch's extremely low message latency minimizes fabric message handling time that results in a high-performance fabric. Routing Cost All Inter Switch Links (ISLs) have a default cost of 1000. The cost of a path between any two switches in the fabric is the sum of the costs of all ISLs. The switches that comprise the fabric always choose the lowest cost path through the fabric to forward frames from the source switch to the destination switch. When constructing a multiswitch configuration, called a cascaded fabric, a frame entering the fabric may pass through eight switches before exiting the fabric. The switch does not enforce the eight-switch limit. It is your responsibility to ensure that the seven-hop limit is not exceeded. The command uRouteShow provides information regarding the cost of the shortest path to another switch from which you can derive the number of hops. The cost should not exceed 7000 (7 x 1000). A fabric using Dell switches in cascaded topologies should be configured to deliver the required bandwidth and fault tolerance with all connections made within the seven-hop maximum limit. DELL CONFIDENTIAL - Preliminary 4/6/00 PowerVault 51F Topologies 2-1

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support.dell.com
PowerVault 51F Topologies
2-1
FILE LOCATION:
S:\SYSTEMS\Boxer\rev_i&t\English\50UWDa00\50UWDc20.fm
DELL CONFIDENTIAL - Preliminary
4/6/00
CHAPTER 2
PowerVault 51F Topologies
This chapter discusses some key factors affecting fabric performance, including the
following:
•
Fabric elements
•
Sample fabric topologies
Fabric Elements
Each fabric is unique and the elements that determine the fabric’s structure include:
•
Class of frames in the fabric
•
Type of host adapters connected to the fabric
•
Bandwidth requirements supported by the fabric
•
Topology of the switches in the fabric
•
Requirements for redundancy and fault tolerance
Regardless of the topology used, the switch’s extremely low message latency mini-
mizes fabric message handling time that results in a high-performance fabric.
Routing Cost
All Inter Switch Links (ISLs) have a default cost of 1000. The cost of a path between
any two switches in the fabric is the sum of the costs of all ISLs. The switches that
comprise the fabric always choose the lowest cost path through the fabric to forward
frames from the source switch to the destination switch.
When constructing a multiswitch configuration, called a cascaded fabric, a frame
entering the fabric may pass through eight switches before exiting the fabric. The
switch does not enforce the eight-switch limit. It is your responsibility to ensure that
the seven-hop limit is not exceeded. The command
uRouteShow
provides informa-
tion regarding the cost of the shortest path to another switch from which you can
derive the number of hops. The cost should not exceed 7000 (7 x 1000).
A fabric using Dell switches in cascaded topologies should be configured to deliver
the required bandwidth and fault tolerance with all connections made within the
seven-hop maximum limit.