No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search


To have a better experience, please upgrade your IE browser.


Configuration Guide - Ethernet Switching

S1720, S2700, S5700, and S6720 V200R012(C00 and C20)

This document describes the configuration of Ethernet services, including configuring MAC address table, link aggregation, VLANs, VLAN aggregation, MUX VLAN, VLAN termination, Voice VLAN, VLAN mapping, QinQ, GVRP, VCMP, STP/RSTP/MSTP, VBST, SEP, RRPP, ERPS, LBDT, and Layer 2 protocol transparent transmission.
Rate and give feedback:
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Setting Values of VBST Timers

Setting Values of VBST Timers


VBST uses the following parameters in spanning tree calculation:
  • Forward Delay: determines the interval for port status transition. On a network where a spanning tree algorithm is used, when the network topology changes, new BPDUs are transmitted throughout the network after a given period of time. During the period, the port that should enter the blocking state may be not blocked and the originally blocked port may be unblocked, causing temporary loops. To address this problem, set the Forward Delay during which all ports are blocked temporarily.
  • Hello time: is the interval at which Hello packets are sent. The switch sends BPDUs to neighboring devices at an interval of the Hello time to check whether links are faulty. If the switch does not receive any BPDU at an interval of Hello time, the switch recalculates the spanning tree due to BPDU timeout.
  • Max Age: determines whether BPDUs expire. The switch determines whether the received BPDU expires based on this value. If the received BPDU expires, the spanning tree needs to be recalculated.

Devices on a ring network must use the same values of Forward Delay, Hello time, and Max Age.

Generally, you are not advised to adjust values of the three parameters. This is because the three parameters are relevant to the network scale. It is recommended that the network diameter be adjusted so that the spanning tree protocol automatically adjusts the three parameters. When the default network diameter is used, the default values of the three parameters are used.

To prevent frequent network flapping, ensure that the values of Hello time, Forward Delay, and Max Age conform to the following formulas:

  • 2 x (Forward Delay - 1.0 second) ≥ Max Age

  • Max Age ≥ 2 x (Hello time + 1.0 second)


  1. Run system-view

    The system view is displayed.

  2. Set values of Hello time, Forward Delay, and Max Age.

    • Run stp vlan { vlan-id1 [ to vlan-id2 ] } &<1-10> timer forward-delay forward-delay

      The value of Forward Delay is set.

      By default, the value of Forward Delay is 1500 centiseconds.

    • Run stp vlan { vlan-id1 [ to vlan-id2 ] } &<1-10> timer hello hello-time

      The value of Hello time is set.

      By default, the value of Hello time is 200 centiseconds.

    • Run stp vlan { vlan-id1 [ to vlan-id2 ] } &<1-10> timer max-age max-age

      The value of Max Age is set.

      By default, the value of Max Age is 2000 centiseconds.

Updated: 2018-12-24

Document ID: EDOC1100038339

Views: 166146

Downloads: 695

Average rating:
This Document Applies to these Products
Related Version
Related Documents
Previous Next