Traffic Monitoring

For a router to function smoothly and effortlessly, monitoring traffic is an essential task. Traffic Monitoring helps you get count of packets going inwards and outwards.

This chapter describes the process to monitor packet drops as part of troubleshooting process.

In routing, the information is passed around in the form of packets. Packets contains unit size data. Sometimes,due to network congestion, or outdated software/hardware the packets fail to reach at their destined location.You can identify packet loss in the form of incomplete information or missing information.

Traffic Statistics with Packet Drop Location

Table 1. Feature History Table

Feature Name

Release

Description

Traffic Statistics with Packet Drop Location

Release 24.4.1

Introduced in this release on: Fixed Systems (8700 [ASIC: K100]); Modular Systems (8800 [LC ASIC: P100])

This feature support is now extended to the Cisco 8712-MOD-M routers.

Traffic Statistics with Packet Drop Location

Release 24.2.11

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

We help you save debugging time to locate packet drops by automatically detecting nonzero traffic drops from the commands running in the background and giving you the exact location of the packet drop.

In earlier releases, you used multiple show commands with their respective locations to detect packet drops.

This feature introduces the show drops all command.

Earlier, finding the exact location of packet drop was a long and tedious process as there are multiple node locations. You were executing show commands with their different locations to detect the packet drop location.

Starting Cisco IOS XR Software Release 24.2.11, finding a packet drop location has become easy and quick. You can use the show drops all command to know the exact packet drop location. This command shows all nonzero traffic-drops in the node at one place. This command automatically runs the required IOS XR debug commands in the background and removes insignificant information from the command output.

The following commands outputs are integrated in the show drops all command:

  • show arp traffic

  • show controllers npu stats traps-all instance instance location location

  • show controllers npu stats voq ingress interface interface name instance all location location

  • show cef drops location location

  • show lpts pifib hardware police location location

  • show spp node-counters location location | inc drop

  • show controllers npu stats counters-drop instance instance location location

Monitor Packet Drops

Use show drops all ongoing location all to see ongoing drops on the system. This command output shows ongoing drops since the last time command was executed. 

Router# show drops all ongoing location all

-----------------------------------------------
Printing Drop Counters for node 0/RP0/CPU0
-----------------------------------------------

-------------------
MODULE cef
-------------------

cef ipv4 drops
------------------
No route drops       : 18

-------------------
MODULE spp
-------------------

      Local Linux Packet drops:             683
         Total Socket RX Drops:             683

-----------------------------------------------
Printing Drop Counters for node 0/0/CPU0
-----------------------------------------------

-------------------
MODULE npu
-------------------

Trap Type                                     NPU  Trap  Punt       Punt  Punt  Punt Configured Hardware   Policer Avg-Pkt Packets              Packets
                                              ID   ID    Dest       VoQ   VLAN  TC   Rate(pps)  Rate(pps)  Level   Size    Accepted             Dropped
====================================================================================================================================================================

INJECT_UP_L3_LOOKUP_FAIL                      0    109  BOTH_RP_CPU 310   1538  6    5000       4878       IFG     1520    18                   0

-------------------
MODULE spp
-------------------

      Local Linux Packet drops:              86
         Total Socket RX Drops:             104
   Drop wrong Mcast pkt on SIM:              18

Use show drops all location all to see the drops from all location or node that have happened in the system. 

Router# show drops all location all

-----------------------------------------------
Printing Drop Counters for node 0/RP0/CPU0
-----------------------------------------------

-------------------
MODULE cef
-------------------

cef ipv4 drops
------------------
No route drops       : 18

-------------------
MODULE spp
-------------------

      Local Linux Packet drops:             683
         Total Socket RX Drops:             683

-----------------------------------------------
Printing Drop Counters for node 0/0/CPU0
-----------------------------------------------

-------------------
MODULE npu
-------------------

Trap Type                                     NPU  Trap  Punt       Punt  Punt  Punt Configured Hardware   Policer Avg-Pkt Packets              Packets
                                              ID   ID    Dest       VoQ   VLAN  TC   Rate(pps)  Rate(pps)  Level   Size    Accepted             Dropped
====================================================================================================================================================================

INJECT_UP_L3_LOOKUP_FAIL                      0    109  BOTH_RP_CPU 310   1538  6    5000       4878       IFG     1520    18                   0

-------------------
MODULE spp
-------------------

      Local Linux Packet drops:              86
         Total Socket RX Drops:             104
   Drop wrong Mcast pkt on SIM:              18

System Log Alerts for Packet Loss

Table 2. Feature History Table

Feature Name

Release Information

Description

System Log Alerts for Packet Loss

Release 24.1.1

You can quickly get notified about any traffic impacting errors within the router's Network Processing Unit (NPU). These notifications are error log messages on the router console for NPU interrupts that affect traffic. To diagnose traffic loss, follow the recommended actions in the log.

Previously, the only way to identify NPU errors that impacted traffic was to run the show asic-error command.

This feature introduces the following changes:

CLI:

This feature introduces the hw-module profile packet-loss-alert command.

YANG Model:

New xpaths for Cisco-IOS-XR-npu-hw-profile-cfg.yang data model

(see GitHub, YANG Data Models Navigator)

Network packet loss can significantly impact the overall experience of end-users, particularly when using real-time applications such as voice or video. Therefore, network administrators need to address such issues promptly to ensure the integrity of these services.

Now you can configure your router to provide immediate alerts in the event of packet loss, along with configuring the duration of packet loss to raise the alert. This feature enables network administrators to quickly identify the specific router within the network that is experiencing the problem. It facilitates a swift and precise response to rectify the issue and maintain optimal network performance.


Note

Only line cards and routers with the Q100, Q200, P100, or G100 based Silicon One ASIC support this feature.

Configuration Example

Execute the hw-module profile packet-loss-alert command to enable this feature, as shown below: 

Router# configure
Router(config)# hw-module profile packet-loss-alert 3Min 
Router(config)# commit

You can configure the duration of packet loss to raise the alert to either 3 minutes or 5 minutes.

Running Configuration

Router# show running-config hw-module profile
hw-module profile packet-loss-alert 3Min

System Log Alert Generated for Packet Loss

When you enable this feature, the router generates a system log message whenever there’s a packet loss for the configured duration. To diagnose the reason for the packet loss, follow the recommended action in the log. 

LC/0/3/CPU0:Nov 4 21:12:47.062 UTC: npu_drvr[213]: %FABRIC-NPU_DRVR-3-ASIC_ERROR_TRAFFIC_IMPACT : [10118] : npu[2]: Potential PACKET_LOSS due to error, please check configuration to see if drop is expected; if not, collect showtech fabric link-include and follow the TAC guideline for this message

Monitor interface

Table 3. Feature History Table

Feature Name

Release

Description

Monitor interface

 Release 24.4.1

The filter physical keyword was introduced, along with new columns InDrops and OutDrops in the output, to provide enhanced monitoring capabilities for physical interfaces.

CLI:

Monitor interface

 Release 7.5.4

The keyword full-name is added, allowing users to display the full names of interfaces, which is particularly useful for interfaces with long or descriptive names.

CLI:

Monitor interface

 Release 7.0.12

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

Monitor interface is introduced to enable real-time monitoring of interface counters on Cisco routers.

This feature introduces the monitor interface command.

The monitor interface command is used to monitor network interface counters in real-time.

This command provides valuable insights into the performance and status of both physical and virtual interfaces on a router.

By leveraging various arguments, you can customize the output to display

  • detailed statistics,

  • full interface names, and

  • filter for physical interfaces.

The monitor interface command is essential for network administrators to diagnose and troubleshoot interface-related issues effectively.