Hitachi US7070447-001 manual FDDI Troubleshooting Tips, Filtering Mode, Forwarding Mode

Draft Level—Hitachi Confidential

FDDI Concepts

Filtering Mode

With FDDI Filtering, packets between FDDI-native devices are filtered at the FDDI Uplink, not at the switch’s bridging table. This method of filtering reduces the burden on the HiSpeed processor. If the FDDI ring is small and the number of native FDDI devices is limited, FDDI filtering is recommended. Maximum number of entries in the FDDI Filtering table is 4096.

Forwarding Mode

With FDDI Forwarding, the MAC addresses of the directly-attached Ethernet devices are placed into the FDDI forwarding table, then only those FDDI packets with destination addresses corresponding in the forwarding table are forwarded to the Ethernet. All other packets are dropped at the FDDI interface, and as a result, reduce the potential load on the HiSpeed processor. If the FDDI ring is very large and the number of directly-attached Ethernet devices is limited, FDDI forwarding should be employed. Maximum number of entries in the FDDI Forwarding table is 256.

Promiscuous Mode

With FDDI Promiscuous mode, all packets will be received and forwarded to the FDDI Uplink. This configuration is not recommended as an increased load will be placed on the HiSpeed processor; thereby dramatically reducing the switch’s performance.

FDDI Troubleshooting Tips

❒The FDDI Uplink module must be inserted into the lower PCI slot only.

❒A multimode fiber (MMF) cable is required for use with the FDDI uplink module. Each port (A or B) requires a duplex (pair) fiber between two adjacent HS150s. Do not use a simplex (single) fiber to connect two adjacent FDDI ports.

❒FDDI Filtering is the default configuration mode.

❒With Spanning Tree enabled, verify that a virtual port ’34 FDDIBRG’ is active and in a Forwarding state. ‘vvp’ or ‘vps 34’

❒Must be running software version 1.4.4 or later.

US7070447-001, Rev 01 12-5