Explains GIL prune behavior for PWHE interfaces, focusing on the interaction between generic interface lists and multicast/broadcast traffic management within advanced pseudowire deployments.
A GIL prune behavior for PWHE interfaces is a network forwarding mechanism that
aligns the PWHE underlay with a Generic Interface List (GIL)
sends PWHE traffic only to interfaces where PWHE is present or replicated, and
limits PWHE replication to the necessary line card locations.
Feature history
The feature history table lists release support for this feature.
| Feature Name |
Release Information |
Feature Description |
|---|---|---|
| Enhance network efficiency and scalability with GIL pruning for PWHE interfaces |
Release 26.1.1 | Introduced in this release on: Centralized Systems (8400 [ASIC: K100]) (select variants only*) *This feature is supported on Cisco 8404-SYS-D router. |
| Enhance network efficiency and scalability with GIL pruning for PWHE interfaces |
Release 25.4.1 |
Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*) *This feature is supported on:
|
| Enhance network efficiency and scalability with GIL pruning for PWHE interfaces |
Release 24.4.1 | Introduced in this release on: Modular Systems (8800 [LC ASIC: P100])(select variants only*) You can now manage hardware resources for a Pseudowire Headend (PWHE) interface more efficiently by limiting PWHE replication to the line card locations where the interfaces listed in the Generic Interface List (GIL) are physically present. This optimization ensures that resource usage is confined to only the necessary line cards. The router internally synchronizes the PWHE underlay with the GIL using a mechanism known as GIL pruning. The GIL consists of a subset of core-facing IGP/LDP-enabled interfaces expected to transmit pseudowire traffic for the PWHE interface. This feature is enabled by default and does not require any user configuration. *This feature is supported on:
|
GIL pruning behavior
GIL pruning is a network forwarding mechanism that
aligns PWHE underlay with a GIL
ensures that PWHE traffic is sent only to the interfaces where PWHE is present or replicated, and
enhances hardware resource usage and allows increased scale of PWHE deployment by limiting the replication of PWHE to necessary interfaces.
This feature eliminates the need for manual synchronization between interfaces in GIL and PWHE underlay next hops.
The router automatically aligns PWHE underlay with the GIL, ensuring that PWHE traffic is only sent to interfaces where PWHE is present or replicated.
The feature reduces unnecessary hardware resource usage by ensuring PWHE traffic is only forwarded to necessary interfaces.
The network performs more efficiently and reliably with optimized forwarding paths and reduced resource wastage.
The feature ensures that forwarding chains are aligned with the updated interface lists, maintaining high performance and reducing potential points of failure.
The feature is enabled by default; no specific configuration is required. You must configure a Generic Interface List (GIL) for PWHE interfaces.
This feature supports only MPLS LDP as the underlay for PWHE interfaces.