57Figure 17 Network diagram2. Configuration procedure# Enable Digest Snooping on GigabitEthernet 3/1/1 of Device A and enable global DigestSnooping on Device A. system-view[DeviceA] interface gigabitethernet 3/1/1[DeviceA-GigabitEthernet3/1/1] stp config-digest-snooping[DeviceA-GigabitEthernet3/1/1] quit[DeviceA] stp config-digest-snooping# Enable Digest Snooping on GigabitEthernet 3/1/1 of Device B and enable global DigestSnooping on Device B. system-view[DeviceB] interface gigabitethernet 3/1/1[DeviceB-GigabitEthernet3/1/1] stp config-digest-snooping[DeviceB-GigabitEthernet3/1/1] quit[DeviceB] stp config-digest-snoopingConfiguring No Agreement CheckIn RSTP and MSTP, the following types of messages are used for rapid state transition on designatedports:• Proposal—Sent by designated ports to request rapid transition• Agreement—Used to acknowledge rapid transition requestsBoth RSTP and MSTP devices can perform rapid transition on a designated port only when the portreceives an agreement packet from the downstream device. RSTP and MSTP devices have the followingdifferences:• For MSTP, the downstream device’s root port sends an agreement packet only after it receives anagreement packet from the upstream device.• For RSTP, the down stream device sends an agreement packet regardless of whether an agreementpacket from the upstream device is received.Figure 18 shows the rapid state transition mechanism on MSTP designated ports.Device C(Root bridge)GE3/1/1 GE3/1/2GE3/1/1GE3/1/2GE3/1/1GE3/1/2Root portDesignated portNormal linkBlocked linkBlocked portDevice A Device BMST region
