Operation Manual – MSTPH3C S3100-52P Ethernet Switch Chapter 1 MSTP Configuration1-481.7 Configuring Digest Snooping1.7.1 IntroductionAccording to IEEE 802.1s, two interconnected switches can communicate with eachother through MSTIs in an MST region only when the two switches have the same MSTregion-related configuration. Interconnected MSTP-enabled switches determinewhether or not they are in the same MST region by checking the configuration IDs ofthe BPDUs between them (A configuration ID contains information such as region IDand configuration digest).As some other manufacturers' switches adopt proprietary spanning tree protocols, theycannot communicate with the other switches in an MST region even if they areconfigured with the same MST region-related settings as the other switches in the MSTregion.This problem can be overcome by implementing the digest snooping feature. If a porton an S3100-52P Ethernet switch is connected to another manufacturer's switch thathas the same MST region-related configuration as its own but adopts a proprietaryspanning tree protocol, you can enable digest snooping on the port. Then theS3100-52P Ethernet switch regards another manufacturer's switch as in the sameregion; it records the configuration digests carried in the BPDUs received from anothermanufacturer's switch, and put them in the BPDUs to be sent to the anothermanufacturer's switch. In this way, the S3100-52P Ethernet switch can communicatewith another manufacturer’s switches in the same MST region.Caution:The digest snooping function is not applicable to edge ports.1.7.2 Configuring Digest SnoopingConfigure the digest snooping feature on a switch to enable it to communicate withother switches adopting proprietary protocols to calculate configuration digests in thesame MST region through MSTIs.I. Configuration prerequisitesThe switch to be configured is connected to another manufacturer's switch adopting aproprietary spanning tree protocol. MSTP and the network operate normally.II. Configuration procedureFollow these steps to configure digest snooping:
