BGP Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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BGP DMZ link bandwidth enhancement

Updated: February 28, 2026

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Overview

Describes enhancements that allow BGP to advertise any valid DMZ link bandwidth value with improved precision, including values less than 1 kbps, for accurate bandwidth signaling.

BGP DMZ link bandwidth enhancement is a BGP feature that

  • accurately advertises all valid link bandwidth values

  • preserves precision in bandwidth signaling, and

  • allows sending and advertising any valid BGP DMZ link bandwidth value, including values less than 1 kilobit per second (kbps).

Benefits of BGP DMZ link bandwidth enhancement

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

BGP DMZ link bandwidth enhancement

Release 25.1.1

Introduced in this release on: Fixed Systems (8200 [ASIC: Q200, P100], 8700 [ASIC: P100, K100], 8010 [ASIC: A100]); Centralized Systems (8600 [ASIC: Q200]); Modular Systems (8800 [LC ASIC: Q100, Q200, P100])

You can now send and advertise any valid BGP DMZ link bandwidth value including values below 1 kilobit per second (kbps).

Previously, BGP rounded smaller link bandwidth values and failed to advertise values below 1 kbps.

The feature introduces these changes:

CLI:

The show bgp command is enhanced to display link bandwidth values in both kbps and bytes per second for improved precision and visibility.

The feature allows you to send and advertise link bandwidth values of any size, overcoming the previous format limitation that restricted values to greater than 1 kbps. With the enhancement, RPL supports 64-bit link bandwidth values.

The key benefits of the feature are:

  • BGP avoids rounding issues that affected smaller bandwidth values.

  • Supports a wider and more granular range of bandwidth values.

  • Precise bandwidth advertisement ensures that any valid link bandwidth value is advertised accurately and preserves network performance metrics.

  • All address families support the feature. However, it is primarily used only with the IPv4 and IPv6 address families that are installed in the RIB by the default and specific VRFs.

  • You cannot use DMZ link bandwidth with Multihop eBGP.

Verify the DMZ link bandwidth enhancement.

Before you begin

Follow these steps to verify the DMZ link bandwidth enhancement.

Procedure

1.

Run the show route command to verify the status of specific routes in the routing table.

Example:

Router#show route 209.165.201.1/27        
...
Routing entry for 209.165.201.1/27
  Known via "bgp 1", distance 200, metric 0
  Tag 2, type internal
  Installed Mar  6 09:14:55.055 for 00:06:10
  Routing Descriptor Blocks
    1.1.1.1, from 1.1.1.1, BGP multi path
      Route metric is 0, Wt is 16000
    1.1.1.2, from 1.1.1.2, BGP multi path
      Route metric is 0, Wt is 8000
...

In the sample output, BGP utilizes link bandwidth values for multipath load balancing and adjusts and distributes weights across different paths.

2.

Run the show cef command to verify load sharing based on weights derived from link bandwidth values.

Example:

Router#show cef 209.165.201.1/27
...
    Weight distribution:
    slot 0, weight 16000, normalized_weight 2
    slot 1, weight 8000, normalized_weight 1

  Level 1 - Load distribution: 0 0 1
  [0] via 1.1.1.1/32, recursive
  [1] via 1.1.1.1/32, recursive
  [2] via 1.1.1.2/32, recursive
...

In the sample output, the load distribution levels indicate how packets are distributed among various paths. The weight distribution values indicate how weights are normalized across various slots.
3.

Run the show bgp command to verify the link bandwidth in bytes per second.

Example:

Router#show bgp 209.165.201.1/27
Thu Mar  6 09:22:09.823 UTC
BGP routing table entry for 209.165.201.1/27
Versions:
  Process           bRIB/RIB   SendTblVer
  Speaker             160385       160385
Last Modified: Mar  6 09:14:55.098 for 00:07:14
Paths: (2 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  2, (received & used)
    1.1.1.1 (metric 20) from 1.1.1.1 (1.1.1.5)
      Origin IGP, localpref 100, valid, internal, best, group-best, multipath
      Received Path ID 1, Local Path ID 1, version 160385
      Extended community: LB:1000:128 
                          (LB non-transitive AS:bytes/sec:1000:16000.0)
      Originator: 1.1.1.5, Cluster list: 1.1.1.1
  Path #2: Received by speaker 0
  Not advertised to any peer
  2, (received & used)
    1.1.1.2 (metric 20) from 1.1.1.2 (1.1.1.5)
      Origin IGP, localpref 100, valid, internal, multipath
      Received Path ID 1, Local Path ID 0, version 0
      Extended community: LB:1000:64 
                          (LB non-transitive AS:bytes/sec:1000:8000.0)
      Originator: 1.1.1.5, Cluster list: 1.1.1.2

In the example show output, BGP advertises a link bandwidth value of 16,000.0 bytes per second for the link bandwidth weight 128 and 8,000 bytes per second for the link bandwidth weight 64.