H3C Technologies H3C SecPath F1000-E - Manual (Page 125)

100
Figure 55 Rapid state transition of an RSTP designated port
If the upstream device is a third-party device, the rapid state transition implementation may be limited.
For example, when the upstream device uses a rapid transition mechanism similar to that of RSTP, and the
downstream device adopts MSTP and does not work in RSTP mode, the root port on the downstream
device receives no agreement packet from the upstream device and sends no agreement packets to the
upstream device. As a result, the designated port of the upstream device fails to transit rapidly and can
only change to the forwarding state after a period twice the Forward Delay.
You can enable the No Agreement Check feature on the downstream device's port to enable the
designated port of the upstream device to transit its state rapidly.
Configuration prerequisites
Before you configure the No Agreement Check function, complete the following tasks:
• Connect a device to a third-party upstream device supporting spanning tree protocols via a
point-to-point link.
• Configure the same region name, revision level and VLAN-to-instance mappings on the two devices,
assigning them to the same region.
Configuration procedure
To make the No Agreement Check feature take effect, enable it on the root port.
To configure No Agreement Check:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter Ethernet interface view or Layer
2 aggregate interface view. interface interface-type
interface-number
N/A
3. Enable No Agreement Check. stp no-agreement-check Disabled by default.
No Agreement Check configuration example
1. Network requirements
As shown in
Figure 56 , Device A connects to a third-party device that has a different spanning tree
implementation. Both devices are in the same region.
The third-party device (Device B) is the regional root bridge, and Device A is the downstream
device.