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

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

Simultaneous monitoring of Adj-RIB-In pre-policy and post-policy views

Updated: September 11, 2026

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Details simultaneous monitoring techniques for Adj-RIB-In pre-policy and post-policy views and provides procedures for configuration to enable comprehensive route-policy diagnostics.

The simultaneous monitoring of Adj-RIB-In pre-policy and post-policy views is a Routing Policy feature that

  • allows you to monitor both pre-policy and post-policy routing information for all BGP peers at the same time,

  • supports multiple monitoring modes including inbound pre-policy route mirroring and route monitoring, inbound post-policy route monitoring, and Local-RIB monitoring, and

  • enables combined operation of inbound post-policy with Local-RIB or inbound pre-policy route monitoring modes in parallel.

You use this feature to gain comprehensive visibility into BGP routing changes before and after policy application, improving your ability to analyze and troubleshoot routing behavior.

  • Monitoring both pre-policy and post-policy views lets you compare routing information before and after policy filters are applied, helping you understand the impact of policies on route selection.

  • The ability to run combined modes in parallel increases flexibility and scalability in large BGP networks.

  • RTBH validation through this feature helps confirm that black hole routes are properly enforced, protecting your network from unwanted traffic.

Table 1. Feature History Table

Feature Name

Release

Description

Simultaneous monitoring of Adj-RIB-In Pre-Policy and Post-Policy views

Release 26.1.1

Introduced in this release on: Centralized Systems (8400 [ASIC: K100]) (select variants only*)

*This feature is now supported on the Cisco 8404-SYS-D routers.

Simultaneous monitoring of Adj-RIB-In Pre-Policy and Post-Policy views

 Release 25.4.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*)

*This feature is now supported on:

  • 8011-32Y8L2H2FH

  • 8011-12G12X4Y-A/D

Simultaneous monitoring of Adj-RIB-In Pre-Policy and Post-Policy views

Release 25.1.1

Introduced in this release on: Fixed Systems (8700 [ASIC: K100], 8010 [ASIC: A100])(select variants only*)

*This feature is supported on:

  • 8712-MOD-M

  • 8011-4G24Y4H-I

Simultaneous monitoring of Adj-RIB-In Pre-Policy and Post-Policy views

Release 24.4.1

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

You can now monitor BGP events and collect BGP route information both before and after applying policy filters. This feature allows you to view the Adj-RIB-In pre-policy and post-policy views simultaneously for all BGP peers, making it easier to troubleshoot routing policies and verify Remotely Triggered Black Hole (RTBH) routes.

This feature introduces these changes:

CLI:

This feature modifies the following commands:

*This feature is supported on:

  • 8212-48FH-M

  • 8711-32FH-M

  • 88-LC1-36EH

  • 88-LC1-12TH24FH-E

  • 88-LC1-52Y8H-EM

Supported monitoring modes

The supported monitoring modes are operational modes that

  • include individual modes such as inbound pre-policy route mirroring (as per RFC 7854), inbound pre-policy route monitoring, inbound post-policy route monitoring, and Local-RIB monitoring, and

  • include combined modes where inbound post-policy route monitoring can operate simultaneously with Local-RIB monitoring or inbound pre-policy route monitoring.

You select these modes based on your monitoring needs to capture routing information at different stages of policy processing.

Benefits of Simultaneous Monitoring

The benefits of simultaneous monitoring of Adj-RIB-In pre-policy and post-policy views are advantages that

  • enhance monitoring by providing visibility into both pre-policy and post-policy routes simultaneously,

  • offer high scalability to support large numbers of routes and neighbors,

  • improve debugging by delivering detailed routing policy monitoring information, and

  • enable Remote Triggered Black Hole (RTBH) validation to ensure correct implementation and enhance network security.

You leverage these benefits to maintain robust network monitoring, facilitate troubleshooting, and strengthen security posture.

Configure simultaneous monitoring of Adj-RIB-In Pre-Policy and Post-Policy views

Before you begin

Note

Before configuring Adj-RIB-In Pre-Policy Route-Monitoring mode, ensure that soft reconfiguration is enabled for all BGP Monitoring Protocol (BMP) supported AFIs under all BMP monitored neighbors. Soft reconfiguration is a prerequisite for Adj-RIB-In Pre-Policy Route Monitoring.

Procedure

  1. Enable BMP on the Router.

    Example:

    Router# configure
Router(config)# bmp server all

  2. Configure inbound pre-policy mode route monitoring.

    Example:

    Router# configure
Router(config)# bmp server all
Router(config-bgp-bmp)# route-monitoring inbound pre-policy

  3. Configure inbound post-policy mode route monitoring.

    Example:

    Router# configure
Router(config)# bmp server all
Router(config-bgp-bmp)# route-monitoring inbound post-policy

  4. Set advertisement interval and scan time.

    Example:

    Router# configure
Router(config)# bmp server all
Router(config-bgp-bmp)# route-monitoring inbound pre-policy
Router(config-bgp-bmp-rmon)# advertisement-interval 15 
Router(config-bgp-bmp-rmon)# scan-time 60

    When both route-monitoring inbound pre-policy and route-monitoring inbound post-policy are configured at the same time, the system uses the lower values for the advertisement interval and scan time from either the default or configured settings of both modes. For example, if the advertisement-interval for pre-policy is set to 30 and for post-policy is set to 15, the value of 15 is used for both modes. This rule also applies to scan-time .

  5. The default BMP mode is now route-mirroring, where uncompressed BGP updates are sent to the BMP server. You can also explicitly configure this mode using the route-mirroring inbound pre-policy command.

    Example:

    Router# configure
Router(config)# bmp server all
Router(config-bgp-bmp)# route-mirroring inbound pre-policy

  6. Verify that the inbound pre-policy and post-policy views for simultaneous monitoring are enabled.

    Example:

    Router# show bgp bmp server 1 detail
Thu Nov 28 10:53:10.659 UTC
BMP server 1
Host 12::2 Port 17001
NOT Connected
Last Disconnect event received : 00:15:10
Flap count : 1
Precedence:  internet
BGP neighbors: 68
VRF: - (0x60000000)
Update Source: - (-)
Update Source Vrf ID: 0x0
Update Mode                       : Rmon-In-Pre-Policy, Rmon-In-Post-Policy
  Rmon-In-Pre-Policy
   Advertisement interval         : 15 secs
   Advertisement interval (Oper)  : 15 secs
   Scanner interval               : 60 secs
   Scanner interval (Oper)        : 60 secs
  Rmon-In-Post-Policy
   Advertisement interval         : 15 secs
   Advertisement interval (Oper)  : 15 secs
   Scanner interval               : 60 secs
   Scanner interval (Oper)        : 60 secs
Flapping Delay                    : 300 secs
Initial Delay                     : 0 secs
Initial Refresh Delay             : 1 secs
Initial Refresh Spread            : 1 secs
Stats Reporting Period            : 0 secs
Queue Route Mon Msg buffer limit  : 503316 KB (Current Server Up Count: 0)
Queue Route Mon Msg buffer usage  : 0 B
Queue write pulse sent            : Nov 28 10:33:23.988, Nov 28 10:38:00.258 (all)
Queue write pulse received        : Nov 28 10:38:00.258
Update Generation in Progress     : No
Reset Walk in Progress            : No
IPv4 Unicast        
  Version                     : 416
  Rmon-In-Pre-Policy:
  Init EOR Version            : 416
  Init EOR Pending count      : 0
  Rmon-In-Post-Policy:
  Init EOR Version            : 416
  Init EOR Pending count      : 0
  Update Generation 
    Last Run                   : Nov 28 10:33:23.982, Count 1
    Walk Currently Stalled     : No, Last Stalled : not set, Count 0
VPNv4 Unicast       
  Version                     : 200
  Rmon-In-Pre-Policy:
  Init EOR Version            : 200
  Init EOR Pending count      : 0
  Rmon-In-Post-Policy:
  Init EOR Version            : 200
  Init EOR Pending count      : 0
  Update Generation 
    Last Run                   : Nov 28 10:33:23.984, Count 1
    Walk Currently Stalled     : No, Last Stalled : not set, Count 0
IPv6 Unicast        
  Version                     : 505
  Rmon-In-Pre-Policy:
  Init EOR Version            : 505
  Init EOR Pending count      : 0
  Rmon-In-Post-Policy:
  Init EOR Version            : 505
  Init EOR Pending count      : 0
  Update Generation 
    Last Run                   : Nov 28 10:33:23.985, Count 1
    Walk Currently Stalled     : No, Last Stalled : not set, Count 0
VPNv6 Unicast       
  Version                     : 320
  Rmon-In-Pre-Policy:
  Init EOR Version            : 320
  Init EOR Pending count      : 0
  Rmon-In-Post-Policy:
  Init EOR Version            : 320
  Init EOR Pending count      : 0
  Update Generation 
    Last Run                   : Nov 28 10:33:23.987, Count 1
    Walk Currently Stalled     : No, Last Stalled : not set, Count 0

TCP: 
  Last message sent: Nov 28 10:33:24.215, Status: Not Connected
  Last write pulse received: Nov 28 10:33:24.311, Waiting: FALSE

Message Stats:
Total msgs dropped   : 0
Total msgs pending   : 0, Max: 587 at Nov 28 10:33:23.988
Total messages sent  : 712
Total bytes sent     : 133462, Time spent: 0.006 secs
  INITIATION         : 1
  TERMINATION        : 0
  STATS-REPORT       : 0
  PER-PEER messages  : 711

  PEER UP messages   : 68
  PEER DOWN messages : 0
  ROUTE-MIR messages : 0
  ROUTE-MON messages : 643
   Last RMon EnQ     : Nov 28 10:33:23.988
   EOR messages      : 278
   Update messages   : 365 (Prefixes: 3254, Err: 0) 
Update gen time spent: 0.005 secs

Neighbor 2001:DB8:1:5 (vrf vrf1)
 Last BMP Activate : Nov 28 10:33:15.065
 First Peer Up EnQ : Nov 28 10:33:15.065
 Last Peer Up EnQ  : Nov 28 10:33:15.065
 Last EOR Pending  : not set
 Last EOR EnQ      : not set
 Last RMon EnQ     : Nov 28 10:33:23.988
  Messages pending : 0
  Messages dropped : 0
  Messages sent    : 3
    PEER-UP        : 1
    PEER-DOWN      : 0

    Rmon-In-Pre-Policy:
    ROUTE-MON      : 1
      Update       : 1 (Prefixes: 10, Err: 0) 

    Rmon-In-Post-Policy:
    ROUTE-MON      : 1
      Update       : 1 (Prefixes: 10, Err: 0) 

Neighbor 2001:DB8:3:5 (vrf vrf1)
 Last BMP Activate : Nov 28 10:33:15.065
 First Peer Up EnQ : Nov 28 10:33:15.065
 Last Peer Up EnQ  : Nov 28 10:33:15.065
 Last EOR Pending  : not set
 Last EOR EnQ      : not set
 Last RMon EnQ     : Nov 28 10:33:23.988
  Messages pending : 0
  Messages dropped : 0
  Messages sent    : 3
    PEER-UP        : 1
    PEER-DOWN      : 0

    Rmon-In-Pre-Policy:
    ROUTE-MON      : 1
      Update       : 1 (Prefixes: 10, Err: 0) 

    Rmon-In-Post-Policy:
    ROUTE-MON      : 1
      Update       : 1 (Prefixes: 10, Err: 0) 

Neighbor 2001:DB8:2:5 (vrf vrf1)
 Last BMP Activate : Nov 28 10:33:15.065
 First Peer Up EnQ : Nov 28 10:33:15.065
 Last Peer Up EnQ  : Nov 28 10:33:15.065
 Last EOR Pending  : not set
 Last EOR EnQ      : not set
 Last RMon EnQ     : Nov 28 10:33:23.988
  Messages pending : 0
  Messages dropped : 0
  Messages sent    : 3
    PEER-UP        : 1
    PEER-DOWN      : 0

....

  7. To view the information about prefixes, advertisement status, and paths learned from the monitored BGP neighbors, use the show bgp bmp mode route-monitoring inbound post-policy table command.

    Example:

    Router# show bgp bmp mode route-monitoring inbound post-policy table
Thu Nov 28 10:54:35.570 UTC

----------------------------------------------
Route monitoring mode : Inbound Post-Policy
----------------------------------------------

Bitmap and Status Codes:
  u: Update send pending        U: Update sent
  w: Withdraw send pending      W: Withdraw sent, path awaiting deletion
  D: Server down                .: Server not configured or mode not applicable

Address-Family : IPv4 Unicast
------------------------------------
BMP prefix table version : 1196

   Network            Version      Neighbor         Adv Status  Flags  Path ID
                                                    87654321
   10.2.2.2/8            1           10.2.2.2           ......DD    0x0e   1
   10.2.0.0/8            2           10.2.2.2           ......DD    0x0e   1
   10.0.1.0/8            3           10.2.2.2           ......DD    0x0e   1
   10.0.2.0/8            4           10.2.2.2           ......DD    0x0e   1
   10.0.0.0/8            5           10.2.2.2           ......DD    0x0e   1
   192.168.0.1/16        6           10.2.2.2           ......DD    0x0e   1
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   4
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   3
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   2
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   1
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   7
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   6
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   5
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   10
   209.165.201.1/27      7           10.2.2.2           ......DD    0x0e   8
   209.165.201.10/27     8           10.2.2.2           ......DD    0x0e   4
   209.165.201.10/27     8           10.2.2.2           ......DD    0x0e   3
   ....
    1. To view the pre-policy and post-policy advertisement statuses in the same table, use the show bgp bmp mode route-monitoring inbound all table command.

      Example:

      Router# show bgp bmp mode route-monitoring inbound all table 
 Thu Nov 28 10:55:03.096 UTC

----------------------------------------------
Route monitoring mode : Inbound All
----------------------------------------------

Bitmap and Status Codes:
  u: Update send pending        U: Update sent
  w: Withdraw send pending      W: Withdraw sent, path awaiting deletion
  D: Server down                .: Server not configured or mode not applicable

Address-Family : IPv4 Unicast
------------------------------------
BMP prefix table version : 1196

   Network            Version      Neighbor         Adv Status  Adv Status  Flags  Path ID
                                                    (Pre)       (Post)
                                                    87654321    87654321
   10.2.2.2/8            1           10.2.2.2           ......DD    ......DD    0x0e   1
   10.2.0.0/8            2           10.2.2.2           ......DD    ......DD    0x0e   1
   10.0.1.0/8            3           10.2.2.2           ......DD    ......DD    0x0e   1
   10.0.2.0/8            4           10.2.2.2           ......DD    ......DD    0x0e   1
   10.0.0.0/8            5           10.2.2.2           ......DD    ......DD    0x0e   1
   192.168.0.1/16        6           10.2.2.2           ......DD    ......DD    0x0e   1
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   4
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   3
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   2
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   1
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   7
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   6
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   5
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   10
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   9
   209.165.201.1/27      7           10.2.2.2           ......DD    ......DD    0x0e   8
   209.165.201.11/27     8           10.2.2.2           ......DD    ......DD    0x0e   4
   209.165.201.11/27     8           10.2.2.2           ......DD    ......DD    0x0e   3
   ....

      This sample output provides the advertisement statuses of both Pre-Policy and Post-Policy views.