16.1.11 Notes on using uplink redundant

<Structure of this section>

(1) About coexistence with other functions

(a) Coexistence with Layer 2 Switch Function

See "Configuration Guide: Coexistence of Vol.1" "22.3 Layer 2 Switch Function and Other Functions".

(b) Coexistence with Layer 2 authentication

[5.2.1 See Coexistence of Layer 2 Authentication with Other Functions.

(c) Coexistence with High Reliability Functions by Redundant Configuration

The following table describes the high-reliability features of redundant configurations that are limited in coexistence with uplink redundants.

Table 16-3: Restricted functionality when uplink and redundant functionality is used together
Functionality	Restrictions
GSRP	Cannot be used

(2) Using the Flash Control Frame Transmit/Receive Function

Check whether the upstream switches support the reception of flush control frames sent by uplink redundancy.

If the upstream switches do not support the flush control frame functionality, the MAC address tables on the switches will not be cleared even if flush control frames are sent from the Switch. As a result, it might take some time before communication is restored.

(3) About configuring flush control frame transmission on trunk ports

If you want to send flush control frames on a trunk port, make sure you specify the destination VLAN. If you do not specify the destination VLAN, untagged flush control frames are sent only when a native VLAN exists. If no native VLAN is configured, flush control frames are not sent.

(4) Configuration Commands with VLAN Down Settings

When you specify one of the configuration commands below related to uplink redundancy for the first time on the Switch, all VLANs temporarily go down. Therefore, before you create a network that uses uplink redundancy, we recommend that you set the following configuration commands beforehand.

switchport backup flush-request
switchport backup interface
switchport backup mac-address-table update exclude-vlan
switchport backup mac-address-table update transmit

(5) When using the port reset function

If a transmission device is installed between an uplink port and a partner switch, link-down may not be detected correctly on the partner switch. When the port reset function is used, the network must be designed so that link-down can be directly detected by the partner switch.

Also, if the port reset function operates while some of the physical ports belonging to the channel group are inactive, the corresponding physical port becomes active as the old active port.

(6) Using the port reset function in a stacked configuration

If the master switch is switched while the port is being brought down by the port reset function in a stack configuration, the corresponding port may remain down. If this happens, execute an operation-command activate on the applicable port.

(7) Stack configuration

When configuring a stack, link aggregation across multiple member switches cannot be set on the primary and secondary ports. Also, you cannot configure primary and secondary ports on the same member switch interface.

(8) Using MAC Address Update Function in Stacked Configurations

When using this function, set the aging period of the learned MAC addressto 300 seconds or more. If the master switch is switched within 300 seconds after the backup switch is initialized, this function may not work properly.