Traffic Mirroring Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

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Additional debug commands

Updated: February 5, 2026

Overview

This section provides additional trace and debug commands used to troubleshoot specific traffic mirroring scenarios, such as missing routes or unresolved ARP. It includes a comprehensive list of platform-specific commands to help verify session status and internal operational data.

This table details the various problem scenarios and how to troubleshoot them.

When..

Then..

there is no route to the destination IPv4 address

use the status command

Router#show monitor-session mon2 status internal
Wed Oct 9 19:24:06.084 UTC
Information from SPAN Manager and MA on all nodes:
Monitor-session mon2 (ID 0x00000001) (Ethernet)
SPAN Mgr: Destination interface tunnel-ip2 (0x0f000034) (down)
Last error: Success
Tunnel data:
Mode: GREoIPv4
Source IP: 2.2.2.2
Dest IP: 130.10.10.2
VRF:
ToS: 0 (copied)
TTL: 255
DFbit: Not set
0/1/CPU0: Destination interface is not configured
Tunnel data:
Mode: GREoIPv4
Source IP: 2.2.2.2
Dest IP: 130.10.10.2
VRF:
ToS: 0 (copied)
TTL: 255
DFbit: Not set

there is a route to the destination IPv4 address
use this command: 
Router#show cef ipv4 130.10.10.2
Wed Oct 9 19:25:12.282 UTC
0.0.0.0/0, version 0, proxy default, default route handler, drop adjacency, internal 0x1001011
0x0 (ptr 0x8e88d2b8) [1], 0x0 (0x8ea4d0a8), 0x0 (0x0)
Updated Oct 9 19:03:36.068
Prefix Len 0, traffic index 0, precedence n/a, priority 15
via 0.0.0.0/32, 3 dependencies, weight 0, class 0 [flags 0x0]
path-idx 0 NHID 0x0 [0x8e2db240 0x0]
next hop 0.0.0.0/32
drop adjacency

a route is present
use this command: 
Router#show cef ipv4 130.10.10.2
Wed Oct 9 19:25:12.282 UTC
0.0.0.0/0, version 0, proxy default, default route handler, drop adjacency, internal 0x1001011
0x0 (ptr 0x8e88d2b8) [1], 0x0 (0x8ea4d0a8), 0x0 (0x0)
Updated Oct 9 19:03:36.068
Prefix Len 0, traffic index 0, precedence n/a, priority 15
via 0.0.0.0/32, 3 dependencies, weight 0, class 0 [flags 0x0]
path-idx 0 NHID 0x0 [0x8e2db240 0x0]
next hop 0.0.0.0/32
drop adjacency

ARP for the next hop is resolved, which is done by invoking a ping command to the destination
the show command output displays this output: 
RP/0/RP0/CPU0:Router1#show monitor-session mon2 status internal
Wed Oct 9 19:32:24.856 UTC
Information from SPAN Manager and MA on all nodes:
Monitor-session mon2 (ID 0x00000001) (Ethernet)
SPAN Mgr: Destination interface tunnel-ip2 (0x0f000034)
Last error: Success
Tunnel data:
Mode: GREoIPv4
Source IP: 2.2.2.2
Dest IP: 130.10.10.2
VRF:
ToS: 0 (copied)
TTL: 255
DFbit: Not set
0/1/CPU0: Destination interface tunnel-ip2 (0x0f000034)
Tunnel data:
Mode: GREoIPv4
Source IP: 2.2.2.2
Dest IP: 130.10.10.2
VRF:
ToS: 0 (copied)
TTL: 255
DFbit: Not set
Information from SPAN EA on all nodes:
Monitor-session 0x00000001 (Ethernet)
0/1/CPU0: Name 'mon2', destination interface tunnel-ip2 (0x0f000034)
Platform, 0/1/CPU0:
Monitor Session ID: 1
Monitor Session Packets: 0
Monitor Session Bytes: 0
0/2/CPU0: Name 'mon2', destination interface tunnel-ip2 (0x0f000034)
Platform, 0/2/CPU0:
Monitor Session ID: 1
Monitor Session Packets: 0
Monitor Session Bytes: 0

These are the additional trace and debug commands for traffic mirroring.

  • show monitor-session platform trace

  • show monitor-session trace

  • debug monitor-session platform

  • debug monitor-session platform all

  • debug monitor-session platform event

  • debug monitor-session platform info

  • show monitor-session status

  • show monitor-session status

  • show monitor-session status errors

  • show monitor-session status internal