MSTP communication between Cisco and H3C Switches

MSTP intercommunication between Cisco and H3C switches 1. MSTP introduces the concept of "INSTANCE" INSTANCE and "REGION" REGION. An instance is a collection of multiple VLANs. In this way, you can bind multiple VLANs to an instance to save communication overhead and resource usage. "Domain" is determined by the domain name, revision level, and format selector. The relationship between VLAN and instance. The domain name, format selector, and revision level all have related fields in the BPDU message. The ing relationship between VLAN and instance is summarized in BPDU packets. Www.2cto.com 2, MSTP intercommunication. Currently, MSTP is used for interconnection between H3C and CISCO switches. According to the protocol, to ensure MSTP communication, their domain configuration information is completely consistent. The default path overhead of the H3C switch is Legacy. The calculation result of the MSTP configuration summary is inconsistent with the DOT1T standard in S. The configuration digest calculated by cisco MSTP does not comply with the DOT1Q standard. In this way, the H3C switches and CISCO switches that are connected do not think that their respective summary information is different even if their domain configurations are the same. MSTP cannot be implemented. H3C MSTP implements intercommunication using the following method: When the H3C and CISCO domain configurations are completely consistent. The configuration digest snooping abstract listening function may be enabled for intercommunication. 3. Note the following When configuring H3C and CISCO switch MSTP intercommunication :. Abstract: The listening function must be enabled when the H3C switch and the CISCO switch domain connected in the same region are configured. Otherwise, a broadcast storm occurs.. Each port in the H3C switch region connected to a CISCO switch must be capable of listening. The Digest listening function cannot be enabled on the boundary port of its domain. Www.2cto.com. You cannot directly change the domain configuration of the H3C switch that enables the digest listening function and its connected CISCO switch. The Digest listening function must be enabled before the change. Otherwise, a broadcast storm occurs.. If the domain is H3C, you do not need to enable the digest feature.. After enabling the digest listening function. The switch keeps the configuration summary received recently. Even if the port that enables the digest listening function fails. The previously received configuration summary still takes effect. Configuration instance: Two cisco1_7 instances. Two floor switches. One is 3550. One is H3C3600 C3550-S3: spanning-tree mode mst spanning-tree pathcost method long (path overhead mechanism: long, short ). H3C-S4: stp enable stp mode mstp stp pathcost-standard dot1q (standard for IEEE80.1t) int g1/1/1 # port into the uplink core switch. Stp config-digest-snooping # enable the digest listening function. Stp compliance dot1s # Set the BPDU format of the Spanning Tree to DOT1S on the port. Exit stp config-digest-snooping # enable the summary listening function in global mode. View problems during the H3C-4s: dis stp brief test: Cisco: spanning-tree pathcost method long (long. short. Www.2cto.com H3C: stp pathcost-standard dot1t (dot1d-1998, dot1t, legacy) is legacy by default. In the test, set cisco to short, H3C unchanged. Because long is 32 bytes and short is 16 bytes, although the port is in forwarding, mstp still fails. H3C BPDU package format: To enable multi-instance intercommunication between devices, you must configure mandatory standard packets on the port of the H3C device. The Pre-STD-Rx issue is displayed on the CISCO switch using show spanning-TREE. G1/1 Desg FWD 200000 128.129 p2p Pre-STD-Rx G1/1 Desg FWD 200000 p2p three methods can be used to change the port status from Pre-STD-Rx to P2P. 1, shut, no shut 2, clear the port: clear spanning-tree detected-protocols interface g1/1 3, use the stp reset command on the H3C Switch