Advanced Feature Bandwidth Reservation

The switch enables this boot configuration flag by default to use advanced features on the switch. If you disable this flag and attempt to enable an advanced feature the switch displays an error message to explain why the advanced feature failed to start, and to remind you that you must enable this boot configuration flag for that advanced feature.

Important

If you change the configuration, you must save the configuration, and then reboot the switch for the change to take effect.

If you disable this feature and save the configuration, any configuration for advanced features remains saved in the configuration file but is not used.

When you disable this feature, you can use all ports for Layer 2 or Layer 3 forwarding of standard unicast and multicast features. Use this mode if you are not configuring advanced features.

When you enable this feature, also known as Full Feature mode, the switch supports advanced features by reassigning some of the front panel ports to be loopback ports.

Advanced Features

The following tables identifies the features that use Advanced Feature Bandwidth Reservation.

Note

Full Feature mode does not support PIM.

Feature support can vary by hardware. For high-level feature support information, see Fabric Engine and VOSS Feature Matrix.

Important

Advanced Bandwidth Feature Reservation must be enabled when using SPBM even if features requiring loopback bandwidth are not used.

Configuration Modes

Depending on the hardware, this feature supports three modes:

• low
• high
• vim

When you select low or high, the corresponding bandwidth of the reserved Ethernet ports is allocated to the loopback required for advanced feature functionality. When you select vim, the bandwidth is allocated from the unused vim slot capacity; you cannot select this parameter if the VIM card is present.

The following table shows the supported modes and the ports reserved as loopback ports by each mode. An empty cell indicates the mode (parameter) is not supported.

Note

For 7520 Series and 7720 Series, you can consider using low bandwidth mode instead of high bandwidth mode to free up two reserved ports for use as regular ports.

Note

To understand restrictions on using reserved loopback ports as front panel ports on the 5420 Series, see 5420 Series.

Reserved Ports

After the switch reserves the appropriate ports to become loopback ports, the ports are no longer visible in the output when you enter show interfaces gigabitEthernet.

By default, for the 5520 Series and 5720 Series switches, if you do not install a VIM in the switch, the switch uses the vim parameter. In this configuration, the VIM ports are used as loopback ports and the Universal Ethernet ports are used as regular uplink ports. When used as regular uplink ports, the port speed for the Universal Ethernet ports is 40 Gbps as a single channel port. Although the maximum supported single channel port speed is 40 Gbps, the ports can be channelized to operate as four 10 or 25 Gbps channels.

If a VIM is already installed in the 5520 Series, the switch uses the low parameter that uses Universal Ethernet ports as loopback ports and VIM ports as regular uplink ports. For the 5720 Series, the switch uses the high parameter that uses Universal Ethernet ports as loopback ports and VIM ports as regular uplink ports.

Important

You must ensure your configuration does not include reserved ports before you enable this feature. If the configuration includes reserved ports, after you enable this feature and restart the switch, the switch stops loading the configuration.