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CloudEngine 8800, 7800, 6800, and 5800 V200R002C50 Configuration Guide - Virtualization

This document describes the configurations of virtualization, including stack and SVF.
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Stack Setup

Stack Setup

A stack is set up after the following stages:
  1. Physical connection setup: When multiple switches are connected in a specific topology according to network requirements, a stack network is established.

  2. Master election: Member switches exchange stack competition packets and elect a master switch according to master election rules.

  3. Topology collection: The master switch collects information about all the member switches and calculates the topology. If some member switches have the same stack member ID, the master switch reassigns stack member IDs to the member switches.

  4. Running: The master switch synchronizes the topology of the entire stack to all the member switches and selects a standby switch.

Physical Connection Setup

Two stack topologies are available: chain topology and ring topology, as shown in Figure 1-5. Table 1-1 compares the two stack topologies in terms of reliability, link bandwidth utilization, and convenience of cable connections.
Figure 1-5 Stack topologies
Table 1-1 Comparison between stack topologies

Topology

Advantage

Disadvantage

Usage Scenario

Chain topology

Supports long-distance stacking because the first and last member switches do not need to be connected by a physical link.

  • Low reliability: If any stack link fails, the stack splits.

  • Low stack link bandwidth efficiency: The entire stack relies on a single path.

A chain topology is recommended when member devices are far from one another and a ring topology is difficult to deploy.

Ring topology

  • High reliability: If a stack link fails, the topology changes from ring to chain, and the stack can still function normally.

  • High link bandwidth efficiency: Data can be forwarded along the shortest path.

The first and last member switches need to be connected by a physical link, so this topology is not appropriate for long-distance stacking.

A ring topology is recommended when member switches are located near one another, because this topology has higher reliability and link utilization.

Role Election

After a stack is set up, member switches exchange stack competition packets to elect a master switch. The member switches compare the following items in the listed order to elect the master switch (the election ends when a winning switch is found):

  1. Running status: The switch that starts first becomes the master switch.

  2. Stack priority: The switch with the highest stack priority becomes the master switch.

  3. Software version: The switch running the latest software version becomes the master switch.

  4. Bridge MAC address: The switch with the smallest bridge MAC address becomes the master switch.

Topology Collection

After a master switch is elected, it collects information about all the member switches and calculates the topology. If some member switches have the same stack member ID, the master switch reassigns stack member IDs to the member switches.

Stable Running

After the master switch completes topology calculation, it synchronizes the topology of the entire stack to all the member switches and selects a standby switch. The master switch compares the following items of member switches in the listed order to select the standby switch (the election ends when a winning switch is found):
  1. Stack priority: The switch with the highest stack priority becomes the standby switch.

  2. MAC address: The switch with the smallest MAC address becomes the standby switch.

Software Version Synchronization

A stack supports software version synchronization among the member switches. The member switches do not have to run the same software version, and they can set up a stack as long as their software versions are compatible with each another. If software version running on a member switch is different from that on the master switch, the member switch downloads the system software from the master switch, restarts with the new system software, and rejoins the stack.

Configuration File Synchronization

A stack uses a strict configuration file synchronization mechanism to ensure that the member switches work like one device.

  • When a stack is set up, each member switch starts with its own configuration file. After switches start, the standby and slave switches combine their stack configurations into the configuration file of the master switch to form the configuration file of the stack system.

  • When the stack is running normally, the master switch manages the entire stack, and synchronizes configurations made by users to the other switches in real time to maintain configuration consistency on all the member switches.

The configuration file synchronization mechanism ensures that the member switches save the same configuration file. If the master switch fails, other member switches can provide services using the same configuration file.

Configuration Combination and Conflict Detection

Configuration Combination

Stack configuration on a switch is saved in the configuration file. When a stack is set up, the standby and slave switches combine their own stack configurations with that of the master switch. The configuration combination rules are as follows:
  • The standby and slave switches combine their stack configurations with that of the master switch, including the stack attribute configuration, stack port configuration, and port split configuration. If the master switch has the offline stack configurations of the standby and slave switches, the stack configuration of the master switch takes effect.

    As shown in Figure 1-6, SwitchA and SwitchB in a stack combine their port configurations. Port 10GE2/0/5 on SwitchA is configured with common services and the configuration conflicts with the port configuration of SwitchB. Because SwitchA is the master switch, the port configuration of SwitchA takes effect.

  • After a stack is set up, the standby and slave switches synchronize their configuration files with the configuration file of the master switch to keep the same configuration with the master switch.

    As shown in Figure 1-6, SwitchB synchronizes its configuration file with that of SwitchA after the stack is set up.

Figure 1-6 Port configuration combination

Configuration Conflict Detection

A configuration conflict may occur if the master switch has offline configurations made for the standby and slave switches, which may cause a stack setup failure. A configuration conflict occurs in the following situations:
  • When member switches combine their stack member port configurations, the number of stack member ports in a stack port exceeds the limit.

  • All stack member ports on the standby and slave switches have the shutdown configuration on the master switch or have configuration conflicts with the stack system.

  • Stack ports of the standby or slave switch have the shutdown configuration or the configuration that conflicts with the stack on the master switch.

  • A stack contains stack member ports of different types.

  • All stack member ports are added to different stack ports.

When any of the preceding conflicts occurs, the standby and slave switches cannot set up a stack with the master switch. In this case, modify the configuration of the master switch or the standby and slave switches to avoid configuration conflicts, and then restart the switches.
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Updated: 2019-04-20

Document ID: EDOC1000166645

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