Cisco Cisco Packet Data Interworking Function (PDIF)
System Settings
▀ Configuring MIO/UMIO Port Redundancy
▄ ASR 5500 System Administration Guide, StarOS Release 18
70
Configuring MIO/UMIO Port Redundancy
Port redundancy for MIO cards provides an added level of redundancy that minimizes the impact of network failures
that occur external to the system. Examples include switch or router port failures, disconnected or cut cables, or other
external faults that cause a link down error.
that occur external to the system. Examples include switch or router port failures, disconnected or cut cables, or other
external faults that cause a link down error.
Caution:
To ensure that system card and port-level redundancy mechanisms function properly, disable the
Spanning Tree protocol on devices connected directly to any system port. Failure to turn off the Spanning Tree protocol
may result in failures in the redundancy mechanisms or service outage.
may result in failures in the redundancy mechanisms or service outage.
By default, the system provides port-level redundancy when a failure occurs, or you issue the port switch to command.
In this mode, the ports on active and standby MIO/UMIO cards have the same MAC address, but since only one of these
ports may be active at any one time there are no conflicts. This eliminates the need to transfer MAC addresses and send
gratuitous ARPs in port failover situations. Instead, for Ethernet ports, three Ethernet broadcast packets containing the
source MAC address are sent so that the external network equipment (switch, bridge, or other device) can re-learn the
information after the topology change. However, if card removal is detected, the system sends out gratuitous ARPs to
the network because of the MAC address change that occurred on the specific port.
In this mode, the ports on active and standby MIO/UMIO cards have the same MAC address, but since only one of these
ports may be active at any one time there are no conflicts. This eliminates the need to transfer MAC addresses and send
gratuitous ARPs in port failover situations. Instead, for Ethernet ports, three Ethernet broadcast packets containing the
source MAC address are sent so that the external network equipment (switch, bridge, or other device) can re-learn the
information after the topology change. However, if card removal is detected, the system sends out gratuitous ARPs to
the network because of the MAC address change that occurred on the specific port.
With port redundancy, if a failover occurs, only the specific port(s) become active. For example; if port 5/1 fails, then
port 6/1 becomes active, while all other active ports on the line card in slot 5 remain in the same active state. In port
failover situations, use the show port table command to check that ports are active on both cards and that both cards are
active.
port 6/1 becomes active, while all other active ports on the line card in slot 5 remain in the same active state. In port
failover situations, use the show port table command to check that ports are active on both cards and that both cards are
active.
Take care when administratively disabling a port that is one of a redundant pair. A redundant pair comprises both the
active and standby ports—for example 5/1 and 6/1. If 5/1 is active, administratively disabling 5/1 through the CLI does
not make 6/1 active. It disables both 5/1 and 6/1 because an action on one port has the same effect on both. Refer to
Creating and Configuring Ethernet Interfaces and Ports in System Interface and Port Configuration Procedures.
active and standby ports—for example 5/1 and 6/1. If 5/1 is active, administratively disabling 5/1 through the CLI does
not make 6/1 active. It disables both 5/1 and 6/1 because an action on one port has the same effect on both. Refer to
Creating and Configuring Ethernet Interfaces and Ports in System Interface and Port Configuration Procedures.
With automatic card-level redundancy, there is no port-level redundancy in an MIO/UMIO failover. The standby
MIO/UMIO becomes active and all ports on that card become active. The system automatically copies all the MAC
addresses and configuration parameters used by the failed MIO/UMIO to its redundant counterpart. The ports on MIOs
keep their original MAC addresses, and the system automatically copies the failed MIO/UMIO’s configuration
parameters to its redundant counterpart.
MIO/UMIO becomes active and all ports on that card become active. The system automatically copies all the MAC
addresses and configuration parameters used by the failed MIO/UMIO to its redundant counterpart. The ports on MIOs
keep their original MAC addresses, and the system automatically copies the failed MIO/UMIO’s configuration
parameters to its redundant counterpart.
Port redundancy can be configured to be revertive or non-revertive. With revertive redundancy service is returned to the
original port when service is restored.
original port when service is restored.
This feature requires specific network topologies to work properly. The network must have redundant switching
components or other devices that the system is connected to. The following diagrams show examples of a redundant
switching topologies and how the system reacts to various external network device scenarios.
components or other devices that the system is connected to. The following diagrams show examples of a redundant
switching topologies and how the system reacts to various external network device scenarios.