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Configuration Guide - Virtualization

CloudEngine 12800 and 12800E V200R002C50

This document describes the configurations of virtualization, including stack and VS.

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Stack Connection Modes

Stack Connection Modes

Links in a stack fall into two types: management links and forwarding links. Management links are used to forward stack management and maintenance packets, and forwarding links are used to forward service packets between stack member switches. Stack member switches can be connected in two modes: main processing unit (MPU) connection and line processing unit (LPU) connection, distinguished by the connections of management links. Figure 1-5 shows the two stack connection modes.
Figure 1-5 Stack connection modes
  • In MPU connection mode, management links and forwarding links are separated. Management links are connected through the system inter-connect ports (SIPs) on MPUs, and forwarding links are connected through ports on LPUs.

    For details about how to connect the SIP ports and service ports, see SIP Port Connections and Service Port Connections.

  • In LPU connection mode, management links and forwarding links are integrated and both connected through ports on LPUs. SIP ports on the MPUs are not connected.

Table 1-1 describes the comparisons between the two connection modes.

Table 1-1 Comparisons between the two connection modes


MPU Connection

LPU Connection

Relationship between management links and forwarding links

Management links and forwarding links are separated from each other and do not affect each other.

Management links and forwarding links are integrated and will affect each other.

Whether management packets occupy bandwidth



System complexity



Delay in communication between stack member switches



Number of potential failure points on the stack management channel



Whether additional cables need to be deployed






You are advised to preferentially use the MPU connection mode. This mode separates management links from forwarding links, ensuring high reliability of the stack system.

SIP Port Connections

SIP ports are located on MPUs. Each MPU has two SIP ports, as shown in Figure 1-6. A SIP port is a combo port consisting of a GE electrical port and a GE optical port. It starts to work immediately after a cable is connected and does not require any configuration. By default, the working mode of a combo port depends on whether the electrical port or optical port has a cable connected first. If the electrical and optical ports are connected at the same time, the combo port works as an optical port.

After a copper module that does not have a cable connected is installed in the optical port of a SIP port on a CE12800S MPU, the optical port goes Down and will not change to an electrical port. You need to remove the copper module so that the electrical port can go Up.

Figure 1-6 SIP ports on an MPU
Figure 1-7 shows the recommended SIP port connections when each stack member switch has two MPUs.
Figure 1-7 SIP port connections
  • Each switch must have at least one SIP port connected.

  • A SIP port on one switch can only be connected to a SIP port on the other switch, and cannot be connected to other SIP ports on the same switch.

Service Port Connections

A stack port contains stack member ports on the same LPU or different LPUs. A maximum of 32 stack member ports can be added to a stack port to improve stack link bandwidth and reliability. Two networking modes are available according to the distribution of member ports, as shown in Figure 1-8.
Figure 1-8 Service port connections
  • N:N networking (N≥1): Two switches use the same number of LPUs to set up a stack. Stack member ports of each switch are located on one or more LPUs.

  • N:M networking (N≥1, M≥2): Two switches use different numbers of LPUs to set up a stack. Stack member ports of each switch are located on one or more LPUs.


    To ensure reliability, it is recommended that each switch use at least two LPUs to set up a stack.

    Stack member ports on an LPU of the local switch can be connected to multiple LPUs of the peer switch. That is, the cross connection mode is supported, as shown in Figure 1-9.
    Figure 1-9 Cross connection mode

    Local stack member ports cannot connect to remote common service ports. Otherwise, traffic forwarding may fail or the switch restarts unexpectedly. Ports on both ends must be configured either as stack member ports or as service ports.

Updated: 2019-03-21

Document ID: EDOC1000166610

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