2.5. Configuring an IP Router with CLI
This section provides information to configure an IP router.
2.5.1. Router Configuration Overview of 7210 SAS-D, 7210 SAS-Dxp, and 7210 SAS-K 2F1C2T
In 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 long, 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 router, the basic configuration tasks that must be performed are:
- Assign a name to the interface.
- Associate an IP address with the interface.
- Associate the interface with a system or a loop-back interface.
A system interface should be configured.
2.5.1.1. System Interface on 7210 SAS-D, 7210 SAS-Dxp, and 7210 SAS-K 2F1C2T
The system interface is associated with the network entity, not a specific interface.
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.
2.5.2. Router Configuration Overview on 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C
In a 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C, an interface is a logical named entity. An interface is created by specifying an interface name under the configure>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 long, 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 router, the basic configuration tasks that must be performed are:
- 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.
2.5.2.1. System Interface on 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C
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:
- The termination point of service tunnels
- The hops when configuring MPLS paths and LSPs
- The 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.
2.5.2.2. Network Interface
 | Note: Network port and network IP interfaces are only supported on the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C. |
A network interface can be configured on a physical port or LAG on a physical or logical port.
2.5.3. Basic Configuration
The most basic router configuration must have the following:
- System name
- System address
The following is a sample a router configuration for 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C.
2.5.4. Common Configuration Tasks
The following sections describe the basic system configuration tasks.
2.5.4.1. 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. Use the following syntax to configure the system name.
The following is a sample system name configuration output.
2.5.4.2. Configuring Interfaces
The following command sequences create a system IP interface.
| Note: The system interface cannot be deleted. |
2.5.4.2.1. Configuring a System Interface
Use the following syntax to configure a system interface.
The following is a sample IP configuration output showing interface information.
2.5.4.2.2. Configure a Network Interface on 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C
Use the following to configure a network interface on 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C.
The following is a sample IP configuration output showing network interface information.
2.5.4.2.3. Configuring IPv6 Parameters on 7210 SAS-D, 7210 SAS-Dxp, 7210 SAS-K 2F6C4T, and 7210 SAS-K 3SFP+ 8C
On the 7210 SAS-D and 7210 SAS-Dxp IPv6 interfaces with static routing can be configured. On the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C, IPv6 interfaces can be configured with static routing or using routing protocols such as OSPFv3 and IS-IS Ipv6 can be configured.
Before configuring the use of IPv6, system resource must be allocated for IPv6 routes on the 7210 SAS-D and 7210 SAS-Dxp using the following command.
The following is a sample interface configuration 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 showing interface information.
2.5.4.3. Configuring an Unnumbered Interface
Use the following syntax to configure an unnumbered interface.
2.5.4.4. Router Advertisement on 7210 SAS-D, 7210 SAS-Dxp, 7210 SAS-K 2F6C4T, and 7210 SAS-K 3SFP+ 8C
| Note: This feature is supported on all 7210 SAS platforms as described in this document, except the 7210 SAS-K 2F1C2T. |
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.
2.5.4.5. Configuring Proxy ARP
| Note: This feature is only supported on the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C. |
To configure proxy ARP, you can configure:
- 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 address(es) 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. For more information about route policies, refer to the 7210 SAS-D, Dxp Routing Protocols Guide and 7210 SAS-K 2F6C4T, K 3SFP+ 8C Routing Protocols Guide.
- 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.
2.5.4.6. 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 are sprayed based on the hashing routine currently supported for IPv4 packets.
When the preferred RTM entry corresponds to a regular IP route, spraying is performed across regular IP next-hops for the prefix.
2.5.4.6.1. Configuration Notes
The following information describes ECMP configuration guidelines.
- IPv6 ECMP is not supported. Only a single IPv6 route for an 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).
2.5.4.7. Deriving the Router ID
| Note: This feature is only supported on the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C. |
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.
2.5.4.8. Configuring an Autonomous System
| Note: This feature is supported only on the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C. |
Configuring an autonomous system is optional. Use the following syntax to configure an autonomous system.
The following is a sample autonomous system configuration output.
2.5.4.9. Configuring Option 82 Handling
Option 82, or “Relay Information Option” is a field in DHCP messages used to identify the subscriber. The Option 82 field can already be filled in when a DHCP message is received at the router, or it can be empty. If the field is empty, the router should add identifying information (circuit ID, remote ID or both). If the field is not empty, the router can decide to replace it.
The following is a sample of a partial BSA configuration with Option 82 adding on a VPLS service. Note that snooping must be enabled explicitly on a SAP or a SDP, as applicable. DHCP snooping configuration on an SDP is supported only on the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C.
2.5.4.10. Configuring a Local DHCP Server
Local DHCP servers provide a standards-based full DHCP server implementation which allows a service provider the option of decentralizing IP address management into the network. Local DHCP servers is supported for IP address assignment when a front-facing port on the 7210 SAS is used for local craft terminal access.
The following CLI syntax shows an example of configuring a local DHCP server (“DHCP”).
The following CLI syntax shows an example of mapping the configured local DHCP server (“DHCP”) to an IP address, and configuring the customer-facing interface (“LAN”) to relay DHCP requests to the local DHCP server.
2.5.5. Service Management Tasks
This section discusses the service management tasks.
2.5.5.1. 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.
Use the following syntax to change the system name.
The following example shows the command usage to change the system name.
The following is a sample system name change output.
2.5.5.2. Modifying Interface Parameters
Starting at the config>router level, navigate down to the router interface context.
To modify an IP address, perform the following steps.
To modify a port, perform the following steps.
The following is a sample interface configuration output.
2.5.5.3. 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.