HP StorageWorks Fabric OS 3.X Document Addendum (AA-RW24A-TE, January 2005)

ISL trunking user guide
152 Fabric OS 3.x Document Addendum
Add the following section at the end of Chapter 1:
Long-Distance Trunking
This section provides information on long-distance trunking between Fabric OS v3.2 switches,
including the SAN Switch 2/8 EL and SAN Switch 2/16. Long-distance ISL trunking is a new
feature for Fabric OS v3.2.x and Fabric OS v4.4.0.
Long-Distance Trunking Requirements
Requirements for ISL Trunking and Extended Fabrics in Fabric OS v3.2.x are as follows:
■ The ISL Trunking and Extended Fabrics licenses are required.
■ All trunk group ports must be part of the same quad.
■ All trunk group ports must be running at 2 Gbit/sec. ISL Trunking does not support 1
Gbit/sec speeds.
■ All trunk group ports must have similar deskew values.
■ ISL Trunking is automatically enabled between adjacent switches that support trunking.
■ All trunking ports in the same trunk group should be configured to be the same Extended
Fabrics distance (for example, LD - LD, L0.5 - L0.5, or L1 - L1).
■ As the distance increases, more buffer credits are needed, and fewer ports can form a trunk
group.
■ SAN Switch 2/8 EL and SAN Switch 2/16 ASICs limit buffer allocation to 63 maximum
per port, so long-distance trunks can be established only up to this buffer limit.
Long-Distance Trunking Summary
The following is a summary of SAN Switch 2/8 EL and SAN Switch 2/16 long-distance
settings and supported distances:
■ L0 less than or equal to 5 km and a 2-, 3-, or 4-port trunk group (normal distance trunking
allocates 26 buffer credits across 4 data VCs)
■ LE less than or equal to 10 km and a 2-, 3-, or 4-port trunk group (allocates 19 buffer
credits across VC2)
■ L0.5 less than or equal to 25 km and a 2- or 3-port trunk group (allocates 29 buffer credits
across VC2)
■ L1 less than or equal to 50 km and a 2-port trunk group (allocates 54 buffer credits across
VC2)
■ L2 less than or equal to 100 km (no trunking support)
■ LD less than or equal to 100 km (trunking supported at distances under 50 km)