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group (Protocols BGP)

Syntax

Hierarchy Level

Description

CAUTION:

Enabling tracing can adversely impact scale and performance and may increase security risk. We strongly recommend using the trace, tracing, or traceoptions commands only under the guidance of a JTAC support engineer. After collecting the debug information, immediately disable tracing to minimize risk and restore normal system performance.

Define a BGP peer group. BGP peer groups share a common type, peer autonomous system (AS) number, and cluster ID, if present. To configure multiple BGP groups, include multiple group statements.

By default, the group’s options are identical to the global BGP options. To override the global options, include group-specific options within the group statement.

The group statement is one of the statements you must include in the configuration to run BGP on the routing device.

Each group must contain at least one peer and can establish up to 2048 peers. Before establishing a BGP session, RPD checks for established peer count for the group. If the peer count is more than 2048 then the BGP session fails.

Options

group-name

Name of the BGP group

link-bandwith auto-sense

Enable this option to automatically detect the bandwidth towards the peer and attach the link-bandwith value to the interface speed over which the BGP route was received. This prevents a policy churn when there is a change in the link-bandwidth of an interface. Make sure that you also include the auto-sense statement in the import policy to enable this feature.

send-non-transitive-link-bandwidth

Enable this option to send non-transitive-link-bandwidth-extended-community towards EBGP neighbors only for link-bandwidth communities. All non-transitive link bandwith community values are advertised including originated or received and readvertised link-bw community.

ttl ttl-value

Configure the maximum time-to-live (TTL) value for the TTL in the IP header of BGP packets.

Configure the maximum time-to-live (TTL) value for the TTL in the IP header of BGP packets.

For BGP multihop scenarios, in which EBGP peers are not directly connected to each other, setting a TTL is optional. The default setting is 64.

For BGP single-hop scenarios, in which external EBGP peers are directly connected to each other, you can, optionally, set the TTL to 255 and configure an inbound firewall filter to allow only BGP control packets with the TTL set to 255. This is in accordance with RFC 3682, The Generalized TTL Security Mechanism (GTSM). For example:

Send all BGP control packets with the TTL set to 255:

Accept only BGP control packets that have the TTL set to 255:

Apply the firewall filter to the inbound interface for the EBGP single-hop peer:

  • Range: 1 through 255, for multihop peers

  • Default: 64 (for multihop EBGP sessions, confederations, and IBGP sessions)

  • Range: 1 or 255, for single-hop peers

  • Default: 1 (for single-hop EBGP sessions)

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 before Junos OS Release 7.4.

link-bandwith auto-sense, and send-non-transitive-link-bandwidth options introduced in Junos OS Release 24.2R1.