What is the working mechanism of SUP in Cisco switch

What is the working mechanism of SUP in Cisco switch

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Hello everyone! As the core device in the enterprise network, Cisco switches’ Supervisor (SUP) component plays a key role in the entire switch system. Today, gracyfiber is pleased to introduce to you the concept, type and working mechanism of SUP in detail, as well as how to upgrade and optimize performance of SUP. We hope to help you better manage and maintain Cisco switches and inject new energy into your digital transformation career. power.

What is Cisco switch SUP (Supervisor)

Let me introduce the concept and role of SUP (Supervisor) in Cisco switches in detail:

The concept and role of SUP (Supervisor):

  • SUP is the core control module in Cisco switches and is responsible for the control and management of the entire switch system.
  • It serves as the “brain” of the switch, providing key control and processing functions for the switch.
  • SUP usually consists of specialized hardware line cards with powerful processing capabilities and rich software functions.

Main functions and responsibilities of SUP:

  • Responsible for the control plane of the switch: SUP runs the operating system of the switch and manages various protocols and functions of the switch.
  • Responsible for the management plane of the switch: SUP provides switch configuration management, monitoring, fault diagnosis and other functions.
  • Processing control packets and management traffic: SUP will process control packets such as BPDU and LLDP.
  • Perform switch software upgrades and backups: SUP is responsible for the management of switch operating systems and software images.
  • Provides a high-availability mechanism for switches: SUP supports redundant backup solutions such as active-standby switching and hot-plugging.

The role of SUP in switch architecture:

  • SUP is located in the central control plane of the switch, coordinating and managing the operation of the entire switch system.
  • The forwarding function of the data plane is provided by the line card of the switch, and the SUP is responsible for controlling the data flow.
  • SUP will also participate in some key switching services, such as VLAN management, ACL application, QoS policy, etc.
  • In general, SUP is the “brain” of the entire switch system and plays a vital role.

To sum up, the SUP (Supervisor) module in Cisco switches shoulders the important responsibilities of the switch control plane and management plane, and is the key to the switch achieving high-performance forwarding, high reliability, and rich functions. Understanding and mastering SUP is crucial for effective configuration and management of switches.

What are the SUP types and features of Cisco switches

Let me introduce to you in detail the characteristics of different models of SUP in Cisco switches:

SUP type and hardware configuration:

  • Cisco switches provide a variety of SUP products, such as SUP2T, SUP6E, SUP9300, etc., to meet different scale and performance requirements.
  • These SUP products differ in hardware parameters such as processor, memory, and number of interfaces.
  • For example, SUP2T uses a dual-core processor with rich memory and interface resources; while SUP6E uses a single-core processor with relatively few hardware resources.

SUP switching capacity and port density:

  • There are significant differences in the switching capacity and line-speed forwarding performance of different SUP models.
  • High-end SUPs such as SUP9300 can achieve a switching capacity of 1.8Tbps per second and support high-density 10 Gigabit Ethernet ports.
  • The switching performance of mid- to low-end SUPs is weak, generally ranging from tens to hundreds of Gbps per second.
  • Port density also affects the overall scale and performance of the switch. High-density SUP supports more line cards and interfaces.

Function support of SUP:

  • Different SUP products also have certain differences in software functions and features.
  • High-end SUPs usually have richer software functions, such as supporting advanced technologies such as MPLS and virtualization.
  • Mid- and low-end SUPs focus more on basic layer 2 and 3 switching and routing functions.
  • Attention also needs to be paid to the software version compatibility between SUPs to ensure co-operation with other hardware modules of the switch.

In general, Cisco switches offer a variety of SUP product lines to meet different scale and performance needs. When selecting a SUP, the most appropriate SUP configuration should be selected based on the specific network deployment scenarios and business needs, weighing the requirements in terms of switching capacity, port density, and software functions. This is critical to achieving high performance and reliability of the switch system.

How does Cisco switch SUP work

Let me introduce the working mechanism of SUP in the switch in detail:

How SUP manages the MAC address table and forwarding engine:

  • SUP is responsible for establishing and maintaining the MAC address table of the switch and recording the MAC address information associated with each port.
  • When the data packet reaches the switch, SUP will query the MAC address table to determine the forwarding destination port of the data packet.
  • If there is no match in the MAC address table, SUP will send the packet to the control plane for processing and learn a new MAC address.
  • SUP will also manage the forwarding engine of the switch and issue forwarding policies to ensure that the data plane can forward data packets efficiently.

How SUP coordinates the control plane and data plane:

  • SUP serves as the control plane of the switch and is responsible for running the operating system and various protocols of the switch.
  • Protocols and functions on the control plane, such as spanning tree, VLAN, routing, etc., are managed and configured by SUP.
  • The forwarding function of the data plane is performed by each interface line card of the switch, and the SUP plays the role of coordination and control.
  • SUP will deliver relevant configuration information and forwarding policies to the data plane, and monitor and manage them.
  • When the control plane changes, the SUP will be synchronized and updated to the data plane in a timely manner to ensure the consistency of the entire switch system.

SUP’s high availability mechanism:

  • To improve the reliability of the switch, many switch models support SUP redundant backup.
  • The switch can be configured with active and standby SUP, and the two SUP modules maintain a high degree of synchronization in terms of configuration and status.
  • When the main SUP fails, the backup SUP will quickly take over to ensure that the switch’s business is not interrupted.
  • Hot swapping of SUP is also an important means to achieve high availability, and can seamlessly replace SUP modules.

So, SUP plays a core control and coordination role in the switch, responsible for managing the MAC address table, configuring forwarding policies, and coordinating the operation of the control plane and data plane. Through redundant backup and other mechanisms, SUP can also improve the reliability and availability of the switch system. An in-depth understanding of the working mechanism of SUP is crucial for effective management and maintenance of switches.

How to upgrade the SUP of a backup Cisco switch

Let me introduce in detail how to upgrade and configure the SUP software:

SUP software version upgrade:

  • Cisco switches support manual upgrade of the SUP operating system version through the command line interface or network management software.
  • Before upgrading, you need to download the software image file of the corresponding SUP model and upload it to the switch.
  • Then execute relevant commands on the switch to upgrade the SUP software version to the new version.
  • Some switch models also support automatic online upgrade of SUP firmware without manual intervention.

Backup and recovery of SUP software configuration:

  • SUP stores key information such as the switch’s system configuration, VLAN settings, and security policies.
  • The SUP configuration information can be exported and saved as a file through the switch’s command line or network management software.
  • When necessary, you can also import the backup configuration file into SUP to quickly restore the switch settings.
  • Some models of SUP also support automatic backup configuration and store it on an external server.

Backup and restore of SUP firmware images:

  • SUP not only contains configuration information, but also saves the operating system and firmware image of the switch.
  • You can manually export the SUP firmware image file for backup to deal with unexpected system failures.
  • When a problem occurs with the SUP, you can restore the backed-up firmware image file to the SUP through the command line or network management software.
  • This can quickly restore the SUP to its normal working state and prevent the switch from being unavailable for a long time.

SUP redundant deployment based on high availability:

  • For critical switch systems, SUP’s active and standby redundancy mechanisms are usually configured.
  • The active and standby SUP maintains real-time synchronization of configuration and status. When the active SUP fails, the standby SUP can quickly take over.
  • This redundant deployment can ensure the continuity of switch services and improve overall reliability.

From the above, we can easily see that the SUP of Cisco switches supports a variety of upgrade and backup mechanisms, which can ensure the security and reliability of the switch system configuration and firmware. Proper management of SUP upgrades and backups is critical to the efficient operation of the switch.

How to optimize the SUP of Cisco switches

Let me summarize for you some best practices for optimizing Cisco switch SUP performance:

Properly configure SUP resources:

  • Select the appropriate model of SUP hardware configuration based on the business needs and scale of the switch.
  • Ensure that SUP’s CPU, memory, interface and other resources meet current and future performance requirements.
  • For key businesses, you can consider deploying SUP’s redundant backup mechanism to improve reliability.

Optimize SUP software functions:

  • Carefully evaluate the various protocols and functions required by the switch and enable only necessary software features.
  • Properly configure ACL, QoS, VLAN and other policies on the SUP to avoid excessive CPU usage.
  • Regularly check the usage of processes and resources on SUP, and optimize and adjust in a timely manner.

Properly deploy SUP and other modules:

  • Properly plan the interconnection topology between the SUP and each line card module of the switch.
  • Ensure that the bandwidth of the SUP’s uplink and downlink interfaces is sufficient to support the overall forwarding performance of the switch.
  • Reasonably allocate control traffic and data traffic between SUP and line cards to avoid bottlenecks.

Targeted monitoring and maintenance:

  • Regularly monitor the key performance indicators of the SUP through the command line or network management software.
  • Focus on key parameters such as SUP’s CPU, memory, and interface utilization.
  • Timely discover and resolve abnormal situations on SUP, such as memory leaks, process failures, etc.

Optimize SUP upgrade and backup strategy:

  • Develop a reasonable SUP software version upgrade plan to ensure version compatibility.
  • Establish a complete SUP configuration and firmware backup mechanism in case of unexpected situations that require recovery.
  • For critical networks, consider using automated upgrade and backup tools.

In short, optimizing SUP performance requires comprehensive consideration from multiple levels such as hardware resource configuration, software function management, system deployment, and monitoring and maintenance. Only by adopting targeted best practices can we ensure that Cisco switch SUP can achieve optimal performance and meet the business needs of the network.


Supervisor (SUP), as the core component of Cisco switches, is responsible for the control plane and management plane of the switch and is crucial to the operation of the entire system. Different models of SUP have certain differences in hardware configuration and functional support, and you need to make a reasonable selection based on network requirements. In actual use, we must pay attention to the upgrade and backup of SUP to ensure that the switch software and configuration information are effectively protected.

At the same time, by properly configuring SUP resources and taking effective management measures, the performance and reliability of the switch can also be significantly improved. Our professional technical team is ready to provide you with a full range of Cisco switch support. If you have any questions during the management and maintenance process,Question, please feel free to contact us for communication.

Cisco Switch SUP FAQ

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