78Follow these steps to configure the timers of MSTP:To do... Use the command... RemarksEnter system view system-view —Configure the forward delay timer stp timer forward-delay timeOptional1500 centiseconds (15 seconds)by default.Configure the hello timer stp timer hello timeOptional200 centiseconds (2 seconds) bydefault.Configure the max age timer stp timer max-age timeOptional2000 centiseconds (20 seconds)by default.NOTE:• The length of the forward delay is related to the network diameter of the switched network. The larger thenetwork diameter is, the longer the forward delay should be. If the forward delay is too short, temporaryredundant paths can be introduced. If the forward delay is too long, it may take a long time for thenetwork to converge. H3C recommends that you use the default setting.• An appropriate hello time enables the device to timely detect link failures on the network without usingexcessive network resources. If the hello time is set too long, the device will take packet loss as a linkfailure and trigger a new spanning tree calculation process. If the hello time is set too short, the devicewill send repeated configuration BPDUs frequently, which adds to the device burden and causes wasteof network resources. H3C recommends that you use the default setting.• If the max age time is too short, the network devices will frequently launch spanning tree calculationsand may take network congestion as a link failure. If the max age is too long, the network may fail totimely detect link failures and fail to timely launch spanning tree calculations, reducing the auto-sensingcapability of the network. H3C recommends that you use the default setting.Configuring the timeout factorThe timeout factor is a parameter used to decide the timeout time in the following formula: Timeout time= timeout factor × 3 × hello time.After the network topology is stabilized, each non-root-bridge device forwards configuration BPDUs tothe downstream devices at the interval of hello time to check whether any link is faulty. If a device doesnot receive a BPDU from the upstream device within nine times the hello time, it assumes that theupstream device has failed and starts a new spanning tree calculation process.Sometimes a device may fail to receive a BPDU from the upstream device because the upstream deviceis busy. If a spanning tree calculation occurs, the calculation can fail and also waste the networkresources. In a very stable network, you can avoid such unwanted spanning tree calculations by settingthe timeout factor to 5, 6, or 7.Follow these steps to configure the timeout factor:To do... Use the command... RemarksEnter system view system-view —
