2.4. Configuring an IP Router with CLI
This section provides information to configure an IP router.
2.4.1. Router Configuration Overview
On a 7210 SAS, an interface is a logical named entity. An interface is created by specifying an interface name under the config>router context. This is the global router configuration context where objects like static routes are defined. An IP interface name can be up to 32 alphanumeric characters, must start with a letter, and is case-sensitive; for example, the interface name “1.1.1.1” is not allowed, but “int-1.1.1.1” is allowed.
To create an interface on a 7210 SAS, the basic configuration tasks are the following.
- Assign a name to the interface.
- Associate an IP address with the interface.
- Associate the interface with a network interface or the system interface.
- Associate the interface with a system or a loop-back interface.
- Configure appropriate routing protocols.
A system interface and network interface should be configured.
2.4.1.1. System Interface
The system interface is associated with the network entity (such as, a specific 7210 SAS-M), not a specific interface. The system interface is also referred to as the loop-back address. The system interface is associated during the configuration of the following entities:
- termination point of service tunnels
- hops when configuring MPLS paths and LSPs
- addresses on a target router for BGP and LDP peering
The system interface is used to preserve connectivity (when routing re-convergence 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.
2.4.1.2. Network Interface
 | Note: Network interfaces are supported on all 7210 SAS platforms as described in this document, except those operating in access-uplink mode. |
A network interface can be configured on a physical port or LAG on a physical or logical port.
2.4.2. Basic Configuration
The most basic router configuration must have the following:
- system name
- system address
The following is a sample router configuration output.
2.4.3. Common Configuration Tasks
The following sections describe basic system tasks.
2.4.3.1. 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 overwrites 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. Use the following syntax to configure the system name.
The following is a sample system name configuration output.
2.4.3.2. Configuring Interfaces
The following command sequences create a system and a logical IP interface. The system interface cannot be deleted.
2.4.3.2.1. Configuring a System Interface
Use the following syntax to configure a system interface.
The following is a sample IP configuration output showing network interface information.
2.4.3.2.2. Configuring IPv6 Parameters
The following is a sample interface configuration output showing the IPv6 default configuration when IPv6 is enabled on the interface.
Use the following syntax to configure IPv6 parameters on a router interface.
The following is a sample configuration output showing interface information.
2.4.3.3. Configuring Router Advertisement
To configure the router to originate router advertisement messages on an interface, the interface must be configured under the router-advertisement context and be enabled (no shutdown). All other router advertisement configuration parameters are optional.
Use the following syntax to enable router advertisement and configure router advertisement parameters.
The following is a sample router advertisement configuration output.
2.4.3.4. Configuring Proxy ARP
To configure proxy ARP, you can configure the following:
- a prefix list in the config>router>policy-options>prefix-list context
- a route policy statement in the config>router>policy-options>policy-statement context and apply the specified prefix list
- In the policy statement entry>to context, specify the host source addresses for which ARP requests can or cannot be forwarded to non-local networks, depending on the specified action.
- In the policy statement entry>from context, specify network prefixes that ARP requests will or will not be forwarded to depending on the action if a match is found. Refer to the 7210 SAS-M, T, R6, R12, Mxp, Sx, S Routing Protocols Guide for more information about route policies.
- apply the policy statement to the proxy-arp configuration in the config>router>interface context
Use the following syntax to configure the policy statement specified in the proxy-arp-policy policy-statement command.
The following is a sample prefix list and policy statement configuration output.
Use the following syntax to configure proxy ARP.
The following is a sample proxy ARP configuration output.
2.4.3.5. ECMP Considerations
| Note:
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When ECMP is enabled and multiple equal-cost next-hops exit for the IGP route, the packets for this route is sprayed based on hashing routine currently supported for IPv4 packets.
When the preferred RTM entry corresponds to a regular IP route, spraying will be performed across regular IP next-hops for the prefix.
2.4.3.5.1. Configuration Notes
The following information describes ECMP configuration guidelines.
- Users must allocate resources using the config system resource-profile router ecmp max-ecmp-routes command (on the 7210 SAS-R6 and R12, the command is config>system>global-resource-profile>router>ecmp>max-ecmp-routes) before ECMP can be enabled using the config router ecmp command. Refer to the 7210 SAS-M, T, R6, R12, Mxp, Sx, S Basic System Configuration Guide for more information about the resource profile command.
- LDP LER ECMP (including LDP over RSVP) is not supported. LDP LSR ECMP is supported on certain platforms. Check the release notes and refer to the 7210 SAS-M, T, R6, R12, Mxp, Sx, S MPLS Guide for information about the platforms that support it and to learn more about it. IPv4 ECMP and LDP LSR ECMP share common set of resources in the hardware. Refer to the 7210 SAS-M, T, R6, R12, Mxp, Sx, S Basic System Configuration Guide for information about resource allocation for IPv4 ECMP and LDP LSR ECMP.
- IPv6 ECMP is not supported. Only a single IPv6 route for a IPv6 destination is programmed in the IPv6 FIB. IPv6 routing and IPv6 IP interfaces cannot be used if IPv4 ECMP is in use (these features are mutually exclusive).
2.4.3.6. 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, then 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.
Use the following syntax to configure the router ID.
The following is a sample router ID configuration output.
2.4.3.7. Configuring an Autonomous System
Configuring an autonomous system is optional. Use the following syntax to configure an autonomous system.
The following is a sample autonomous system configuration output.
2.4.3.8. Configuring Static Routes
The 7210 SAS supports both static routes and dynamic routing to next-hop addresses.
Refer to the 7210 SAS-M, T, R6, R12, Mxp, Sx, S Routing Protocols Guide for information about configuring OSPF, RIP, IS-IS, and BGP routing.
Only one next-hop IP address can be specified per IP interface for static routes.
Use the following syntax to create static route entries.
| Note: If ldp-sync is enabled on a static route, the LDP synchronization timer must also be configured on the associated interface, using the config router if ldp-sync-timer command. |
2.4.4. Service Management Tasks
This section describes the following service management tasks.
2.4.4.1. 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 overwrites the previous entry.
Use the following syntax to change the system name.
The following shows the command usage to change the system name.
The following is a sample system name change configuration output.
2.4.4.2. Modifying Interface Parameters
Starting at the config>router level, navigate down to the router interface context.
The following shows the command usage to modify an IP address.
The following shows the command usage to modify a port.
The following is a sample interface configuration output.
2.4.4.3. 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.
- Before loop-back IP interface can be deleted, it must first be administratively disabled with the shutdown command.
- After the interface has been shut down, it can then be deleted with the no interface command.