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chained-composite-next-hop

 

Syntax

Hierarchy Level

Note

The [edit logical-systems] hierarchy level is not supported on the QFX10000 switches.

Release Information

Statement introduced in Junos OS Release 12.1.

Description

Allows you to configure the chained composite next hops for devices handling ingress or transit traffic in the network.

Chained composite next hops help to facilitate the handling of large volumes of transit traffic in the core of large networks by allowing the router to process much larger volumes of routes. A chained composite next hop allows the router to direct sets of routes sharing the same destination to a common forwarding next hop, rather than having each route also include the destination. In the event that a network destination is changed, rather than having to update all of the routes sharing that destination with the new information, just the shared forwarding next hop is updated with the new information. The chained composite next hops continue to point to this forwarding next hop which now contains the new destination.

On platforms containing only MPCs, such as PTX Series Packet Transport Routers, the MX80 router, the MX2020 router, and the QFX10000 switches, chained composite next hops are enabled by default. On MX Series 5G Universal Routing Platforms containing both DPC and MPC FPCs and on T4000 Core Routers containing MPC and FPCs, chained composite next hops are disabled by default and need to be explicitly configured.

To explicitly configure chained composite next hops, include the enhanced-ip statement at the [edit chassis network-services] hierarchy level. However, take the following into consideration when enabling the enhanced-ip mode:

  • Non-service DPCs do not work with enhanced network services mode options. Only MPCs, MS-DPCs, and MS-MPCs provide support for the enhanced-ip configuration.

  • If you configure chained composite next hops on MX Series routers with both MPCs, and DPCs or DPCEs, the network services mode must be changed from enhanced-ip to ethernet for the DPC or DPCE to come online.

    You can verify the FPC status in such cases, using the show chassis fpc command output, where the DPCs and DPCEs are marked as FPC misconfiguration.

Note
  • When chained composite next hops are enabled on a device, the BGP connections are reset.

  • On MX Series routers with DPCs or DPCEs, only the l3vpn option is supported under the ingress configuration statement; all other configuration options and functionality are not supported.

  • The transit statement and the associated functionality is supported only on PTX Packet Transport Routers and QFX10000 switches.

  • On MX Series routers, removing the chained-composite-next-hop statement from a PE device configuration causes all IBGP sessions to be torn down and triggers the BGP session to flap as well. A similar change on a router configured as a route reflector does not have any effect, however.

    The following is a sample system log message that is generated to record such an event:

  • Starting with Junos OS Release 17.2, you cannot configure chained-composite-next-hop ingress l3vpn extended-space on a logical system.

The remaining statements are explained separately. See CLI Explorer.

Default

This statement is disabled by default.

Options

ingressEnable or disable composite chained next hop for ingress traffic.
transit(PTX and QFX10000) Enable or disable composite chained next hop for transit traffic. Starting in Junos OS Release 14.1, the transit l3vpn statement is enabled by default on PTX Series Packet Transport Routers only.

The remaining statements are explained separately. See CLI Explorer.

Required Privilege Level

routing—To view this statement in the configuration.

routing-control—To add this statement to the configuration.