2.10.1. System Interface

The system interface is associated with a network entity (such as a specific Nokia router), not a specific interface. The system interface is also referred to as the loopback address. The system interface is associated during the configuration of the following entities:

The system interface is used to preserve connectivity (when routing reconvergence is possible) when an interface fails or is removed. The system interface is used as the router identifier. A system interface must have an IP address with a 32-bit subnet mask.

2.10.2. Network Interface

A network interface can be configured on one of the following entities:

For the 7950 XRS, a network interface can be configured on either a physical port or Ethernet LAG interface.

2.12.1. Configuring a System Name

Use the system command to configure a name for the device. The name is used in the prompt string. Only one system name can be configured. If multiple system names are configured, the last one configured will overwrite the previous entry.

If special characters are included in the system name string, such as spaces, #, or ?, the entire string must be enclosed in double quotes. To configure the system name:

The following example shows the system name output:

2.12.2. Configuring Interfaces

The following command sequences create a system and a logical IP interface. The system interface assigns an IP address to the interface, then associates the IP interface with a physical port. The logical interface can associate attributes like an IP address or port.

The system interface cannot be deleted.

2.12.3. Deriving the Router ID

The router ID defaults to the address specified in the system interface command. If the system interface is not configured with an IP address, the router ID inherits the last four bytes of the MAC address. The router ID can also be manually configured in the config>router router-id context. On the BGP protocol level, a BGP router ID can be defined in the config>router>bgp router-id context and is only used within BGP.

If a new router ID is configured, protocols are not automatically restarted with the new router ID. The next time a protocol is initialized, the new router ID is used. An interim period of time can occur when different protocols use different router IDs. To force the new router ID, issue the shutdown and no shutdown commands for each protocol that uses the router ID, or restart the entire router.

It is possible to configure SR OS to operate with an IPv6 only BOF and no IPv4 system interface address. When configured in this manner, the operator must explicitly define IPv4 router IDs for protocols such as OSPF and BGP because there is no mechanism to derive the router ID from an IPv6 system interface address.

To configure the router ID:

The following example shows a router ID configuration:

2.12.4. Configuring a Confederation

Configuring a confederation is optional. The AS and confederation topology design should be carefully planned. Autonomous system (AS), confederation, and BGP connection and peering parameters must be explicitly created on each participating router. Identify AS numbers, confederation numbers, and members participating in the confederation.

See the BGP section for CLI syntax and command descriptions.

To configure a confederation:

The following example shows the configuration of the confederation topology in Confederation Configuration.

Note: Confederations can be preconfigured prior to configuring BGP connections and peering. Each confederation can have up to 15 members.

The following example shows a confederation configuration:

2.12.5. Configuring an Autonomous System

Configuring an autonomous system is optional. To configure an autonomous system:

The following example shows an autonomous system configuration:

2.12.6. Configuring Overload State on a Single SFM

When a router has fewer than the full set of SFMs functioning, the forwarding capacity can be reduced. Some scenarios include:

An overload condition can be set for IS-IS and OSPF to enable the router to still participate in exchanging routing information, but route all traffic away from it when insufficient SFMs are active. This is achieved using the following CLI commands:

These cause an overload state in the IGP to trigger the traffic reroute by setting the overload bit in IS-IS or setting the metric to maximum in OSPF. When PIM uses IS-IS or OSPF to find out the upstream router, a next-hop change in the IS-IS or OSPF will cause PIM to join the new path and prune the old path, which effectively also reroutes the multicast traffic downstream as well as the unicast traffic.

When the problem is resolved, and the required compliment of SFMs become active in the router, the overload condition is cleared, which will cause the traffic to be routed back to the router.

The conditions to set overload are:

2.13.1. Changing the System Name

The system command sets the name of the device and is used in the prompt string. Only one system name can be configured. If multiple system names are configured, the last one configured will overwrite the previous entry.

To change the system name:

The following example shows the configuration to change the system name:

The following example shows the system name change:

2.13.2. Modifying Interface Parameters

Starting at the config>router level, navigate down to the router interface context.

To modify an IP address:

To modify a port:

The following example shows the interface configuration:

2.13.3. Deleting a Logical IP Interface

The no form of the interface command typically removes the entry, but all entity associations must be shut down and/or deleted before an interface can be deleted.