Routing Protocols

AS loop check in BGP Nnetworks (MX304, MX10004, and MX10008)—We have enabled Autonomous systems (AS) path loop check for external BGP (EBGP) and internal BGP (IBGP) sessions by default. The loop check is made in the BGP peer's AS path domain. Use this feature to configure and manage AS path loop detection on Junos devices.

You can disable AS path loop check for IBGP sessions including all routing instances using the no-loop-check statement at the [edit protocols bgp defaults ibgp] hierarchy level.

[See no-loop-check.]

BGP prefix limit based on route target to limit VPN prefixes (MX304, MX10004, and MX10008)—In typical L3VPN deployments, you can limit routes at the customer edge peer level with the prefix-limit configuration for a BGP peer family. We have shifted this control to a central location such as the route reflector or an AS boundary router (ASBR) so that routes originating at all sites in a VPN are taken into account. BGP maintains and enforces the prefix limit as specified by the route target communities originating at various VPN sites to limit the number of prefixes a BGP peer can advertise or receive to conserve resources.

[See prefix-limit.]

Configure BGP keepalive value independent of holdtimer value (MX2008)—BGP uses hold time to terminate unresposive sessions. The hold time resets each time a BGP message is received on a BGP connection. If messages stop, a keepalive timer triggers a keepalive message. By default, this keepalive timer is one third of the negotiated BGP hold time, if greater than zero. You can now configure the keepalive timer independently of the hold time between 1 second and 21845 seconds. Include the keepalive-time statement at the [edit protocols bgp] hierarchy level.

[See keepalive-time.]

Generate static RT-Constrain route based on community or wildcard (MX304, MX10004, and MX10008)—When the RT-Constrain feature is partially deployed in a network, the resource saving benefit is lost. We have extended the static RT-Constrain feature to generate host static RT-Constrain entries from fully qualified route targets configured in the routing policy. You can assign BGP communities or a wildcard route target on the static RT-Constrain route. You can also configure the static RT-Constrain route's origin AS in the network layer reachability information (NLRI) while retaining the global AS number.

IS-IS multi-instance support on a single interface (ACX5448, MX204, MX240, MX301, MX304, MX480, MX960,MX2008, MX2010, MX2020, MX10003, MX10004, MX10008, MX10016, QFX5100VC, QFX10002-60C, QFX5110, QFX5120, QFX5200, QFX5210, QFX10002, QFX10008, and QFX10016)—We have enhaced the IS-IS multi-instance feature to support multiple IS-IS instances on the same logical interface with instance identifier TLV 7.

Include the instance-id statement at the [edit protocols isis-instance name hierarchy level.

[See How to Configure Multiple Independent IGP Instances of IS-IS.]

Path quality profile sharing for GLB multi-link support on IP Fabric (MX10004)—While we support larger Clos networks and more GPUs, the TH5 chipset can only support 64 profiles. In Clos networks with five or more stages, some nodes, like super spines exceed 64 next-next-hop nodes. We can reuse the profiles under specific conditions to support more than 64 next-next-hop nodes. We support GLB for Clos networks with profile sharing in hyperscaler artificial intelligence/machine learning (AI/ML) fabrics containing tens of thousands of leaves or GPUs.

[See profile-sharing.]

Replace BGP AS path to maintain network interoperability (MX204, MX240, MX304, MX480, MX960, MX2008, MX2010, MX2020, MX10003, MX10004, MX10008, and MX10016)—Define a routing policy to match and replace a list of autonomous systems (AS) numbers or private AS numbers with the local AS number of the BGP peering session to maintain network interoperability. This configuration works only on AS sequences and not on AS sets. In route-reflector scenarios, in addition to using external BGP (EBGP), enable internal BGP (IBGP) to leverage this capability. Include the policy action as-path-replace as-list | private statement at the [edit policy-options policy-statement statement-name then] hierarchy level to activate the feature.

[See Autonomous Systems for BGP Sessions.]