ProLiant BL p-Class GbE2 Interconnect Switch Application Guide

Spanning Tree Protocol 63
Configuring Port Fast Forwarding
Use the following CLI commands to enable Port Fast Forwarding on an external port.
>> # /cfg/l2/stp 1/port 19 (Select port 19)
>> Spanning Tree Port 19# fastfwd ena (Enable Port Fast Forwarding)
>> Spanning Tree Port 19# apply (Make your changes active)
>> Spanning Tree Port 19# save (Save for restore after reboot)
Fast Uplink Convergence
Fast Uplink Convergence enables the GbE2 to quickly recover from the failure of the primary link or trunk group
in a Layer 2 network using Spanning Tree Protocol. Normal recovery can take as long as 60 seconds, while the
backup link transitions from Blocking to Listening to Learning and then Forwarding states. With Fast Uplink
Convergence enabled, the GbE2 immediately places the secondary path into Forwarding state, and sends
multicasts of addresses in the forwarding database (FDB) and ARP table over the secondary link so that upstream
switches can learn the new path.
Configuration guidelines
When you enable Fast Uplink Convergence, GbE2 software automatically makes the following configuration
changes:
• Increases the bridge priority to 65500 so that it does not become the root switch.
• Increases the cost of all of the external ports by 3000, across all VLANs and Spanning Tree Groups. This
ensures that traffic never flows through the GbE2 to get to another switch unless there is no other path.
When you disable Fast Uplink Convergence, the bridge priorities and path cost are set to their default values for
all STP groups.
Configuring Fast Uplink Convergence
Use the following CLI commands to enable Fast Uplink Convergence on external ports:
>> # /cfg/l2/upfast ena (Enable Fast Uplink convergence)
>> Layer 2# apply (Make your changes active)
>> Layer 2# save (Save for restore after reboot)
Hot Links
For network topologies that require Spanning Tree to be turned off, Hot Links provides basic link redundancy with
fast recovery.
Hot Links consists of up to three triggers. A trigger consists of a pair of layer 2 interfaces, each containing either
an individual port or trunk. One interface is the Master, and the other is a Backup. While the Master interface is
set to the active state and forwards traffic, the Backup interface is set to the standby state and blocks traffic until
the Master interface fails. If the Master interface fails, the Backup interface is set to active and forwards traffic.
Once the Master interface is restored, it transitions to the standby state and blocks traffic until the Backup
interface fails.
You may select either a physical port or a static trunk as a Hot Link interface. Only cross-connect ports (17-18)
and external ports (19-24) can be members of a Hot Links trigger interface.
Forward Delay
The Forward Delay timer allows Hot Links to monitor the Master and Backup interfaces for link stability before
selecting one interface to transition to the active state. Before the transition occurs, the interface must maintain a
stable link for the duration of the Forward Delay interval.
For example, if you set the Forward delay timer to 10 seconds (/cfg/l2/hotlink/trigger x/fdelay 10),
the switch will select an interface to become active only if a link remained stable for the duration of the Forward
Delay period. If the link is unstable, the Forward Delay period starts again.