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The Lab test: STP edge-port enable can speed up STP converge

Publication Date:  2018-01-27 Views:  72 Downloads:  0
Issue Description

Traffic Direction

Tester Port

Traffic Rate (Frames/Second)

Uplink traffic: S5300 --> S5700

TC7/10 --> TC7/9

10000

Downlink traffic: S5700 --> S5300

TC7/9 --> TC7/10

10000

Uplink traffic: Cisco 3750 --> S5700

TC6/12 --> TC7/9

10000

Downlink traffic: S5700 --> Cisco 3750

TC7/9 --> TC6/12

10000

Switch: S9303

Software: V100R006C00SPC800

Patch: V100R006SPH016

The S9303-1 is STP root bridge primary and the S9303-2 is STP root bridge backup. We will compare the STP convergence time when the S5300 is configred edge-port and not configured edge-port.

Alarm Information

none

Handling Process

We will restart the S9303-1 and observe the convergence time T1 when the S5300 is not configured edge-port. And then we will configure the edge-port on S5300, restart the S9303-1 again, and observe the convergence time T2, compare those two time.

  1. Restart the S9303-1;
  2. Record the STP convergence time:

The service interruption duration is as follows.

Traffic Direction

Service Interruption Duration

Uplink traffic: S5300 --> S5700

29.99s

Downlink traffic: S5700 --> S5300

31.21s

  1. Configuring the edge-port on S5300;

  1. Restart the S9303-1 again;
  2. Record the STP convergence time:

The service interruption duration is as follows.

Traffic Direction

Service Interruption Duration

Uplink traffic: S5300 --> S5700

2.7s

Downlink traffic: S5700 --> S5300

0.608s

  1. Compare the convergence time;

According to the recording, we can come to a conclusion: Configuring the edge-port on access switch port that connect to end terminal ,when the STP root bridge switchover, the MSTP convergence time will be reduced from about 30s to about 3s.

Root Cause

An edge port does not participate in spanning tree calculation, so when enable edge-port, the spanning tree  calculation range is reduced, thus speeding up the STP converge.

Solution

When configure STP network, if we know the port connect to end terminal, we can configure this port as edge-port.

Suggestions

When configure STP network, if we know the port connect to end terminal, we can configure this port as edge-port. When configure edge-port, we suggest enable stp bpdu-filter on this port too.

END