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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.

Description

Enables 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.

You can configure the chained composite next hops with the following options for BGP labeled unicast (BGP-LU) on MX204, MX480, MX960, MX10003, and VMX routers handling ingress or transit traffic in the network:

  • BGP-LU for IPV4 in the ingress router—set routing-options forwarding-table chained-composite-next-hop ingress labeled-bgp inet
  • BGP-LU on the transit router—set routing-options forwarding-table chained-composite-next-hop transit labeled-bgp

You can also configure class of service (CoS) and define rewrite rules for ingress and transit chained composite next hop for BGP-LU. The labeled-bgp options are supported only on Modular Port Concentrator (MPC) 9 (MPC9) and previous models of line cards.

Chained composite next hops are enabled by default on platforms with only MPC line cards, including the following:

  • PTX Series Packet Transport Routers

  • MX80 routers

  • MX2020 routers

  • QFX10000 switches

Chained composite next hops are disabled by default, and you need to explicitly enable this feature on the following platforms and line cards:

  • MX Series 5G Universal Routing Platforms with both Dense Port Concentrators (DPCs) and MPC Flexible PIC Concentrators (FPCs)

  • T4000 Core Routers containing MPC and FPCs

When you 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, Multiservices Modular PIC Concentrators (MS-MPCs), and MultiServices Dense Port Concentrators (MS-DPCs) support the enhanced-ip configuration.

  • If you configure chained composite next hops on MX Series routers with both MPCs and DPCs (or Enhanced DPCs [DPCEs]), you must change the network services mode from enhanced-ip to ethernet for the DPCs (or DPCEs) 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.

  • On MX series routers with MPC9 and the previous models of line cards, only the labeled-bgp option and the l3vpn option are 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:

  • You cannot configure chained-composite-next-hop ingress l3vpn extended-space on a logical system.

Default

This statement is disabled by default or doesn't need to be configured on platforms that enable it by default.

Options

ingress

Enable or disable composite chained next hop for ingress traffic.
transit

(PTX and QFX10000) Enable or disable composite chained next hop for transit traffic. 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.

Release Information

Statement introduced in Junos OS Release 12.1.

Related Documentation