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RLI 39603, Technical Review

 

source-packet-routing

Syntax

Hierarchy Level

Release Information

Statement introduced in Junos OS Release 17.4R1 for the MX Series and PTX Series with FPC-PTX-P1-A.

telemetry option introduced in Junos OS Release 18.3R1 for the MX Series and PTX Series with FPC-PTX-P1-A.

inherit-label-nexthops and retry-timer statements introduced in Junos OS Release 19.1R1 on MX Series routers.

Description

Enable Source Packet Routing in Networking (SPRING) or segment routing for traffic engineering packets for protocols that support segment routing. For example, you can configure segment routing capability for a BGP address family to steer traffic according to network requirements.

To enable segment routing traffic engineering for a BGP family, configure segment-routing-te at the [edit protocols bgp family inet|inet6] and [edit protocols bgp group group-name neighbor neighborfamily inet|inet6] hierarchy levels. Also, configure sr-preference-override at the [edit protocols bgp family inet|inet6 source-packet-routing] hierarchy level. This allows BGP to support segment routing policies and to steer traffic based on the segment list.

A policy action color: color-mode:color-value is configured at the [edit policy-options community namemembers] hierarchy level to categorize segment routing traffic. The color value is attached to BGP communities when exporting prefixes from inet-unicast and inet6-unicast address families, which associates a BGP community with a segment routing policy path definition.

Options

inherit-label-nexthopsInherit label next hops for first hop in all the segment lists.

When the inherit-label-nexthops is configured at the [edit protocols source-packet-routing] hierarchy, it is applied globally, and takes precedence over individual segment-list level configuration.

For dynamic non-colored static LSPs, that is the PCEP-driven segment routing LSPs, the inherit-label-nexthops statement must be enabled globally, as the segment-level configuration is not applied.

lsp-external-controller nameSpecify an external path computing entity, typically the network controller.
maximum-segment-list-depthSpecify a maximum segment list depth for segment routing traffic engineering policies.

Default: The default value is 5.

Range: 1 through 16.

preferenceRoute preference for segment routing traffic engineering routes.
retry-timerNumber of seconds to wait before trying to reconnect to the auto-translate service if the previous attempt failed. Connections may fail if there is no link, or node, for a given IP address, or if the link or node does not have a SID.

Default: 30 seconds

Range: 1 through 600

sr-preferenceSpecify a preference for static segment routing policies. BGP chooses a segment routing policy with a higher value over policies with lower values.

Range: 0 through 4,294,967,295

sr-preference-overrideSpecify a preference override for static segment routing policies that BGP uses to select a segment routing policy. BGP chooses a policy with a higher value over policies with lower values.

Default: The default value is 100

Range: 0 through4,294,967,295

The remaining statements are explained separately. Search for a statement in CLI Explorer or click a linked statement in the Syntax section for details.

Required Privilege Level

routing—To view this statement in the configuration.

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

segment-list

Syntax

Hierarchy Level

Release Information

Statement introduced in Junos OS Release 17.4R1 for MX Series and PTX Series with FPC-PTX-P1-A.

ip-address statement introduced in Junos OS Release 18.1R1 on MX Series routers.

inherit-label-nexthops, node-type, and auto-translate statements introduced in Junos OS Release 19.1R1 on MX Series routers.

Description

Specify an name to identify the segment routing list (used in traffic engineering policy) and the explicit path for source routing label switched path (LSPs) to traverse through traffic engineering segments. The segment list is essentially a stack of segment identifiers.

Starting in Junos OS release 19.1R1 for MX and PTX Series routers, you can enable a translation service to translate next-hop IP addresses into the corresponding segment identifier (SID) labels. The translation service keeps track of the node reached at each hop.

When configured, the segment-list of a segment routing traffic engineering (SR-TE) LSP accepts IP addresses for all the hops along the path. These IP addresses can be either the loopback address of a node, or the IP address of a link, as identified by the node-type. When auto-translation is enabled, next hop IP addresses are automatically translated to corresponding SIDs using the translation service. A retry rate can be set for the retry timer at the source-packet-routing hierarchy level.

Note

The segment list enables BGP and static segment routing LSP to steer traffic based on segment routing policies. When a segment list is used by the protocol BGP, the BGP protocol validates these segment identifiers and selects valid segments for traffic engineering.

Options

<hop-name>Indicates the next hop in the segment routing traffic engineering policy (SR-TE).
  • ip-address—Specify the IP address of the hop. For a segment-list to be used by a non-colored segment routing LSP, the first hop must specify an IP address.

  • label—Specify the SID label of the hop in a segment routing traffic engineering segment list. In static segment routing LSPs, the source routing path uses the segment list only if the second to Nth hop specifies segment identifiers (SID) labels.

    Note

    The range is from 0 to 1,048,576 and is applies to BGP and static segment routing LSPs.

  • label-type—Use with the option below to indicate that the specified address is the IP address of the node, for example, its loopback address, as opposed to that of a link.

    • node—Hops that have been specified as node are translated to a prefix SID, which can be either a node SID or an anycast SID depending on the type of hop IP address. IP addresses not identified as node are consider to be a link.

    Note

    If the first hop is a node, for LSP resolution to work correctly, inherit-label-nexthops must be enabled at either source-packet-routing hierarchy level, or at the relevant segment-list hierarchy level.

auto-translate This option must be enabled before a given segment list can use IP addresses instead of SIDs for any hop other than the first hop. In addition, all hops in the segment list must have IP addresses. If any hops on the list have both an IP address and a label configured, the label will be retained. Link addresses are only translated into labels if the preceding node advertises an adjacency SID for the address (otherwise translation fails).
Note

In Junos OS Release 19.1R1, for auto-translate to work for OSPF, RSVP for segment routing must be enabled on all participating interfaces.

  • protected—(Optional) Enable this option to ensure the adjacency SID is eligible to have a backup path, and that a B-flag is set in adjacency SID advertisements. Note that unless mandatory is also selected, the choice succeeds regardless.

    • mandatory—(Optional) Enable this option to have translation fail if any unprotected links are found in the hop-list.

  • unprotected—(Optional) Enable this option to ensure that no backup path is calculated for a specific adjacency SID, and that a B-flag is not set in adjacency SID advertisements. Note that unless mandatory is also selected, the choice succeeds regardless.

  • mandatory—(Optional) Enable this option to have translation fail if any protected links are found the hop-list.

inherit-label-nexthopsInherit label next hops for first hop in this segment list that have both IP address and label configured in the first hop.

You can configure the inherit-label-nexthops statement globally or individually for each segment list.

The inherit-label-nexthops statement takes effect only when the segment list first hop has both IP address and SID label present.

If the inherit-label-nexthops is not configured at the [edit protocols source-packet-routing segment-list] hierarchy, and the first hop in the segment list has both IP address and label specified, the default behavior is to use the IP address.

Required Privilege Level

routing—To view this statement in the configuration.

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