F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices Network Management Configuration Guide-6PW100

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• The STP device is shut down or removed.
• The STP device transitions to MSTP or RSTP mode.
Suppose Device A running STP, Device B with no spanning tree feature enabled, and Device C running
RSTP or MSTP are connected in order. Device B will transparently transmit STP BPDUs, and the port on
Device C and connecting to Device B will transition to the STP mode. After you enable the spanning tree
feature on Device B, to run RSTP or MSTP between Device B and Device C, you must perform an mCheck
operation on the ports interconnecting Device B and Device C, in addition to configuring the spanning
tree to operate in RSTP or MSTP mode on Device B.
To forcibly transition the port to operate in the original mode, you can perform an mCheck operation. An
mCheck operation takes effect on a device that operates in MSTP or RSTP mode.
The following methods for performing mCheck produce the same result.
1148BPerforming mCheck globally
Ste
p
Command
168. Enter system view.
system-view
169. Perform mCheck. stp mcheck
1149BPerforming mCheck in interface view
Ste
p
Command
170. Enter system view. system-view
171. Enter Ethernet interface view or Layer 2 aggregate interface
view.
interface interface-type interface-number
172. Perform mCheck.
stp mcheck
442BConfiguring digest snooping
As defined in IEEE 802.1s, connected devices are in the same region only when their MST region-related
configurations (region name, revision level, and VLAN-to-instance mappings) are identical. A spanning
tree device identifies devices in the same MST region by determining the configuration ID in BPDU
packets. The configuration ID includes the region name, revision level, and configuration digest, which is
in 16-byte length and is the result calculated via the HMAC-MD5 algorithm based on VLAN-to-instance
mappings.
Because spanning tree implementations vary with vendors, the configuration digests calculated via
private keys are different. Devices of different vendors in the same MST region cannot communicate with
each other.
To enable communication between an HP device and a third-party device, enable the digest snooping
feature on the port that connects the HP device to the third-party device in the same MST region.
1150BConfiguration prerequisites
Before you enable digest snooping, make sure associated devices of different vendors are connected
and running spanning tree protocols.
1. Configuration restrictions and guidelines