McDATA® 4Gb SAN Switch for HP p-Class BladeSystem Installation Guide (AA-RW1XA-TE, June 2005)

20 Planning
Zones
Zoning divides the fabric for purposes of controlling device discovery. Devices in the same zone
automatically discover and communicate freely with all other members of the same zone. The zone
boundary is not secure; traffic across zones can occur if the source knows the address of the destination.
The following rules apply to zones:
• Zones that include members from multiple switches need not include the ports of the inter-switch links.
• Zones can overlap; that is, a port can be a member of more than one zone.
• Membership can be defined by domain ID and port number, or port worldwide name.
• Zoning supports FL_Ports and F_Ports.
Performance
The switch supports class 2 and class 3 FC service with a maximum frame size of 2148 bytes at
transmission rates of 1-Gbps, 2-Gbps, or 4-Gbps. An external port adapts its transmission speed to match
that of the device to which it is connected prior to login when the connected device powers up. Related
performance characteristics include the following:
• Distance, page 20
• Bandwidth, page 21
• Latency, page 21
Distance
Consider the physical distribution of devices and switches in the fabric. Choose SFP transceivers that are
compatible with the cable type, distance, FC revision level, and the device. Refer to ”Specifications” on
page 51 for more information about cable types and transceivers.
Each FC port is supported by a data buffer with an 8-credit capacity; that is, 8 maximum sized frames. For
fibre optic cables, this enables full bandwidth over the following approximate distances:
• 13 kilometers at 1-Gbps (0.6 credits/Km)
• 6 kilometers at 2-Gbps (1.2 credits/Km)
• 3 kilometers at 4-Gbps (2.4 credits/km)
Beyond these distances, however, there is some loss of efficiency because the transmitting port must wait
for an R_RDY response before sending the next frame.
Longer distances can be spanned at full bandwidth by extending credits to G_Ports, F_Ports, and E_Ports.
Each port can donate 7 credits to a pool from which a recipient port can borrow. The recipient port also
loses a credit in the process. For example, you can configure a recipient port to borrow 7 credits from one
donor port for a total of 14 credits (7+7=14). This will support communication over the following
approximate distances:
• 23 Km at 1-Gbps (14÷0.6)
• 12 Km at 2-Gbps (14÷1.2).
• 5 Km at 4-Gbps (14÷2.4)
MaxZonesInZoneSets Maximum number of zones that are components of zone
sets (2000), excluding the orphan zone set, that can be
stored in the switch’s zoning database. Each instance of a
zone in a zone set counts toward this maximum.
MaxMembersPerZone Maximum number of members in a zone (2000)
MaxMembersPerAlias Maximum number of members in an alias (2000)
Table 2 Zoning limits
Limit Description