N Commands
This chapter describes the Cisco NX-OS unicast routing commands that begin with the letter N.
name
To specify a master group name, use the name command. To revert to the default setting, use the no form of this command.
Syntax Description
Defaults
Command Modes
Command History
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Usage Guidelines
The name command changes a regular Hot Standby Redundancy Protocol (HSRP) group into a master group.
If you do not specify a name, a unique name is automatically generated.
Examples
This example shows how to specify a master group name:
Related Commands
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name-lookup
To enable the translation of Open Shortest Path First (OSPF) router IDs to host names, either by looking up the local hosts database or querying domain name server (DNS) names in IPv6, use the name-lookup command. To stop displaying OSPF router IDs as DNS names, use the no form of this command.
Syntax Description
Defaults
Command Modes
Command History
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Usage Guidelines
The name-lookup command makes it easier to identify a device because it displays the device by name rather than by its router ID or neighbor ID.
Examples
This example shows how to enable the translation of OSPF router IDs to host names, either by looking up the local hosts database or querying DNS names in IPv6:
This example shows how to stop displaying OSPF router IDs as DNS names:
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Configures an Open Shortest Path First (OSPF) routing instance. |
neighbor
To configure a BGP neighbor (router, vrf) and enter the neighbor configuration mode, use the neighbor command. To remove an entry, use the no form of this command.
neighbor { ip-addr | ip-prefix / length | ipv6-addr | ipv6-prefix / length } [ remote-as { as-num [. as-num ] | route-map name }
no neighbor { ip-addr | ip-prefix / length | ipv6-addr | ipv6-prefix / length } [ remote-as { as-num [. as-num ] | route-map name }]
Syntax Description
Defaults
Command Modes
Neighbor address-family configuration
Router bgp configuration
Command History
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Usage Guidelines
Use the neighbor command to enter the BGP neighbor configuration mode. When you enter the neighbor command, the prompt changes to switch(config-router-neighbor)#.
From the BGP neighbor configuration mode, you can perform the following actions:
- address-family —Configure an address-family (router, neighbor, vrf). See the address-family (BGP) command for information.
- description description — Describes the neighbor. You can enter up to 80 characters including spaces.
- disable-connected-check —Disables the connection verification for the directly connected peer. Use the disable-connected-check command is to disable a check for an eBGP peer that is directly connected to the local router. BGP triggers a connection check automatically for all eBGP peers that are known to be single hop away, unless you disable this check with the disable-connected-check command. BGP does not bring up sessions if the check fails. BGP considers an EBGP peer is a single hop away, if the eBGP peer does does not have the ebgp-multihop command configured (that is, the time-to-live (TTL) value is one).
This command is ignored if the route-map keyword is used in the neighbor command.
- dont-capability-negotiate —Turns off the negotiate capability with this neighbor.
- dynamic-capability —Enables the dynamic capability.
- ebgp-multihop —Accepts and attempts BGP connections to external peers that reside on networks that are not directly connected. This command is ignored if the route-map keyword is used in the neighbor command.
Note
You should enter this command under the guidance of Cisco technical support staff only.
- exit —Exits from the current command mode.
- inherit peer-session session-name —Configures a peer to inherit the configuration from another peer-session template. To remove an inherit statement from a peer-session template, use the no form of this command.
- no —Negates a command or sets its defaults.
- transport connection-mode passive —Allows a passive connection setup only. To remove the restriction, use the no form of this command.
- remove-private-as —Removes the private AS number from the outbound updates.
- shutdown —Administratively shuts down this neighbor.
- timers keepalive-time —Configures keepalive and hold timers in seconds. The range is from 0 to 3600. The default is 60.
- update-source { ethernet mod / port | loopback virtual-interface | port-channel number [ . sub-interface ]} —Specifies the source of the BGP session and updates. The range for virtual-interface is from 0 to 1023. The range for number is from 0 to 4096. The range for sub-interface is from 1 to 4093.
The Cisco NX-OS software allows BGP sessions to use any operational interface for TCP connections, when you enter the update-source command in neighbor configuration mode. To restore the interface assignment to the closest interface, which is called the best local address, use the no form of this command.
You must use the update-source command must to enable IPv6 link-local peering for internal or external BGP sessions.
Examples
This example shows how to configure a single-hop eBGP peering session between two BGP peers that are reachable on the same network segment through a local loopback interfaces on each router:
This example shows how to source BGP TCP connections for the specified neighbor with the IP address of the loopback interface rather than the best local address:
This example shows how to source IPv6 BGP TCP connections for the specified neighbor in autonomous system 64496 with the global IPv6 address of loopback interface 0 and the specified neighbor in autonomous system 64498 with the link-local IPv6 address of Ethernet interface 2/1:
Related Commands
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net
To configure an Intermediate System-to-Intermediate System (IS-IS) network entity (NET) for the routing process, use the net command. To remove a NET, use the no form of this command.
Syntax Description
NET network services access point (NSAP) name or address for the IS-IS routing process; see the “Usage Guidelines” section for additional information about valid values. |
Defaults
Command Modes
Router configuration
VRF configuration
Command History
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Usage Guidelines
An IS (intermediate system) is identified by an address known as a network access point (NASAP). The NSAP is divided up into three parts as specified by ISO/AI 10589:
- Area address—This field is of variable length, composed of high order octets, and it excludes the System ID and N-selector (NSEL) fields. This area address is associated with a single area within the routing domain.
- System ID—This field is 6 octets long and should be set to a unique value with level-1 and level 2. The system IS defines an end system (ES) or an IS in an area. You configure the area address and the system ID with the NET command. You can display the system ID with the show isis topology command.
- NSEL—This field is called the N-selector, also referred to as the NSAP, and it specifies the upper-layer protocol. The NSEL is the last byte of the NSAP and identifies a network service user. A network service user is a transport entity or the IS network entity itself. When the N-selector is set to zero, the entire NSAP is called a network entity title (NET).
A NET is an NSAP where the last byte is always the n-selector and is always zero. A NET can be from 8 to 20 bytes in length. The NET is formatted as follows: XX.AAAA.AAAA.AAAA[.AAAA].XX.
Under most circumstances, you should configure one NET only. It is possible to configure two or three NETs, but you should not configure more than one NET except for the following unusual circumstances:
- A network configuration has multiple areas that are merged.
- One area in the IS-IS process is being split into multiple areas.
Configuring multiple NETs in these two circumstances can be temporarily useful because multiple area addresses enable you to renumber an area individually as needed.
If you are using IS-IS to perform IP routing only (no connectionless network service routing is enabled), you must configure a NET to define the router ID and area ID.
Examples
This example shows how to configure a router with a NET which consists of the system ID 0000.0c11.1110 and area address 47.0004.0(1)04d.0001:
Related Commands
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network
To configure an IP prefix to advertise, use the network command. To remove the IP prefix to advertise, use the no form of this command.
network ip-addr | ip-prefix / length mask mask-num [ route-map name ]
no network ip-network | ip-prefix / length mask mask-num [ route-map name ]
Syntax Description
Defaults
Command Modes
Neighbor address-family configuration
Router bgp configuration
Command History
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Usage Guidelines
The IP prefix to advertise is considered for bestpath and advertisement to peers only if a route of equal or more specificity is present in the routing table.
Examples
This example shows how to configure an IP prefix to advertise:
nexthop route-map
To specify that Border Gateway Protocol (BGP) routes are resolved using only next hops whose routes match specific characteristics, use the nexthop route-map command. To remove the route map, use the no form of this command.
Syntax Description
Route map name. The name can be any alphanumeric string up to 63 characters. |
Defaults
Command Modes
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Usage Guidelines
Use the nexthop route-map command to configure route policy filtering for next hops.
BGP next-hop filtering allows you to specify that when a next-hop address is checked with the RIB, the underlying route for that next-hop address is passed through the route map. If the route map rejects the route, the next-hop address is treated as unreachable.
BGP marks all next hops that are rejected by the route policy as invalid and does not calculate the best path for the routes that use the invalid next-hop address.
Examples
This example shows how to configure a route map to filter the next-hop address:
switch(config)# route-map CHECK-BGP25 deny 10
switch(config-route-map)# match ip address prefix-list FILTER25
switch(config-route-map)# match source-protocol ospf-o1
switch(config-route-map)# exit
switch(config)# ip prefix-list FILTER25 seq 5 permit 0.0.0.0/0 le 25
switch(config)# router bgp 1.0
switch(config-router)# address-family ipv4 unicast
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Configures the delay timers for BGP next-hop address tracking. |
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Defines the conditions for redistributing routes from one routing protocol into another. |
nexthop trigger-delay
To specify that Border Gateway Protocol (BGP) delay for triggering next-hop calculations, use the nexthop trigger-delay command. To set the trigger delay to the default value, use the no form of this command.
nexthop trigger-delay { critical delay | non-critical delay }
no nexthop trigger-delay { critical delay | non-critical delay }
Syntax Description
Defaults
Critical delay: 3000 milliseconds.
Noncritical delay: 10000 milliseconds.
Command Modes
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Usage Guidelines
Use the nexthop trigger-delay command to modify when BGP processes next-hop address tracking events.
The non-critical delay value must always be set to at least equal or greater than the critical delay value.
The delay should be slightly higher than the time it takes for the Interior Gateway Protocol (IGP) to settle into a steady state after some event (IGP convergence time).
Examples
This example shows how to modify the next-hop address tracking delay:
switch(config)# router bgp 1.0
switch(config-router)# address-family ipv4 unicast
switch(config-router-af)# nexthop trigger-delay critical 5000 non-critical 20000
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no isis passive-interface
To re-enable the sending of routing updates on an Intermediate System-to-Intermediate System (IS-IS) interface and activates only those interfaces that need adjacencies, use the no isis passive-interface command.
no isis passive-interface {level-1 | level-1-2 | level-2}
Syntax Description
Defaults
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Usage Guidelines
Examples
This example shows how to re-enable sending of routing updates on an IS-IS interface and activates only those interfaces that need adjacencies:
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Allows all IS-IS interfaces to be set as passive by default. |
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