Chapter 3 Digest Snooping; Introduction; Configuring Digest Snooping; Prerequisites - Huawei Quidway S6500 Series Operation Manual

Operation Manual - STP
Quidway S6500 Series Ethernet Switches

3.1 Introduction

According to IEEE 802.1s, two connected switches can communicate through MSTIs
(multiple spanning tree instances) in a MSTP (multiple spanning tree protocol) domain
only when they are configured with the same domain settings. With MSTP employed,
interconnected switches determine whether or not they are in the same domain by
checking the configuration IDs of the BPDUs between them. (Configuration ID
comprises information such as domain ID and configuration digest.)
As some switches come with some proprietary protocols concerning STP employed,
they cannot communicate with other switches in MSTP domains even both of these two
types of switches are configured with the same domain configuration settings.
This can be overcome by implementing digest snooping. Digest snooping enables a
switch to track and maintain configuration digests of other switches that are in the same
domain by examining their BPDUs and insert corresponding configuration digests in its
BPDUs destined for these switches, through which switches of different type are
capable of communicating with each other in a MSTP domain.

3.2 Configuring Digest Snooping

Configure digest snooping on a switch to enable it to communicate in MSTP domains
with other switches that are configured with some proprietary protocols to calculate
configuration digest through MSTI.

3.2.1 Prerequisites

Switches of different manufacturers are interconnected in a network and have MSTP
properly employed. The network operates properly.

3.2.2 Configuration Procedure

Table 3-1 Configure digest snooping
Operation
Enter
view
Enter
interface view

Chapter 3 Digest Snooping

Command
system
system-view
Ethernet interface
interface_num
Huawei Technologies Proprietary
—
interface_type: Interface type
interface_type
interface_num:
number
3-1
Chapter 3 Digest Snooping
Remark
Interface