Connect to the nc socket from an external server. For example, the nc socket was started in the vrf-default network namespace. So, connect over an interface that is in the same VRF.

[root@localhost ~]#nc -vz 192.168.122.22 5000
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to 192.168.122.22:5000.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.

The Linux system contains a number of individual network namespaces. Each namespace contains a set of interfaces that map to a single interface in the XR control plane. These interfaces represent the exposed XR interfaces (eXI). By default, all interfaces in IOS XR are managed through the IOS XR configuration (CLI or YANG models), and the attributes of the interface (IP address, MTU, and state) are inherited from the corresponding configuration and the state of the interface in XR.

With the new Packet I/O functionality, it is possible to have an IOS XR interface completely managed by Linux. This also means that one or more of the interfaces can be configured to be managed by Linux, and standard automation tools can be used on Linux servers can be used to manage interfaces in IOS XR.

Note	Secondary IPv4 addresses cannot be managed by Linux.

This section describes basic docker operations and the commands required for hosting and maintaining the applications:

Commands for Maintaining Containers

• Restart Policies

  Docker restart policies start the containers automatically after the router reboots.

  
  [ios:~]$docker run -d --restart 
  

• Clean up Containers and Images

  You can clean images, containers, volumes, and networks that are dangling (and not associated with a container) by using the docker system prune command.

  [ios:~]$docker container prune

  and

  [ios:~]$docker image prune

• Monitor Docker (View Docker Statistics)

  You can view performance metrics, such as utilization of memory and CPU, and container-specific metrics, such as CPU limit and memory limit.

  [ios:~]$docker stats --no-stream
  CONTAINER ID        NAME                CPU %               MEM USAGE / LIMIT     MEM %               NET I/O             BLOCK I/O           PIDS
  a1b719df1091        nifty_leavitt       0.00%               2.035MiB / 30.78GiB   0.01%               648B / 0B           0B / 0B             2
  
  

Note	For generic docker commands, see the Docker Release 18.05 documentation. (https://docs.docker.com)

1. Build the docker image following the standard docker build procedures. See here.

   The docker image is transferred to the IOS XR router (target router) using one of the following ways:

   • The docker image is pulled from the docker image registry into the target router (or)

   • The docker image is saved as the tar file in the build host and then the tar file is copied into the target router from the build host.

2. Start the docker container and run the application on the router.

3. Verify the hosted application in the docker container.

• Versatile Traffic Crafting: Create complex nested packets, such as IPinIPinIPinIP, to test and diagnose a variety of scenarios.

• In-Production Diagnosis: Directly diagnose routers in a problem state without disrupting the network setup.

• CPU-based packet generators are not optimized for high-speed packet processing; therefore, they may not match the performance of NPU-based packet generators.

• CPU-based packet generators can potentially introduce higher CPU loads during operation, which may affect the router performance.

• The probe packet rate is 40 kpps for Cisco 8000 Series Routers.

The following diagram depicts the software architecture of CPU-based packet generator.

The Cisco IOS-XR PacketIO serves as a host for third-party applications on the XR platform, with PacketIO infrastructure facilitating packet transport and interactions between Linux and XR environments. Leveraging this existing infrastructure, the CPU-based packet generator is implemented as a Linux application and packaged within the supported XR platform base image, ensuring seamless distribution.

The Linux infrastructure maintains a database of all XR interfaces including bundles. The CPU-based packet generator is used to send a specific packet type over a chosen interface.

• Support different packet types: The CPU-based packet generator supports various packet types, including:

  • ARP

  • TCP

  • UDP

  • GRE

  • MPLS

  • IPinIP

  • ICMPv4

  • ICMPv6

• Corrupt or error packet generation: There are times when routers receive packets that are either corrupted or contain errors for various reasons. To identify and troubleshoot these issues, it becomes necessary to generate similar packets that can be used for debugging purposes. The CPU-based packet generator can create these packets and aid debugging.

  Examples include:

  • IPv4 packet with TTL 0

  • IPv4 packet with wrong checksum

  • IPv4 packet with mismatch between IP option length field and the IP header

You can use CPU-based packet generator using:

• CLI: Use the packetgen command with different options to run the tool from XR bash environment. As the XR interfaces show up as Linux interfaces in bash environment, you can directly use the XR interface names.

• pcap file: Use an already captured pcap file in production routers and replay it.

  packetgen -i interface_name -pcap pcap_file

Router# bash
[ios:~]$ packetgen -i Hu0_0_0_25 -ip-ttl 32 -progress -count 50 -icmp-type 8 -ip-dst 10.0.0.2 -ip-src 10.0.0.1 --ethernet-smac 78:c5:51:84:48:c4 --ethernet-dmac 00:00:00:1e:ca:fc
INFO[0000] [ETH IP ICMP]
INFO[0000] Setting SRC IP to 10.0.0.1
INFO[0000] Setting DST IP to 10.0.0.2
INFO[0000] Opening Handle Hu0_0_0_25
INFO[0000] Opened Handle Hu0_0_0_25
INFO[0000] Starting Packet Injection
Sending Packets... 2% | | (1/50, 254 packet/s) [0s:0s] /* Truncated output. */

Address Age Hardware Addr State Type Interface
10.0.0.1 - 78c5.5184.48c4
Interface ARPA HundredGigE0/0/0/25
10.0.0.2 00:50:23 0000.001e.cafc Dynamic ARPA HundredGigE0/0/0/25

Source stats:
Stat Name      Port Name            Control Packet Tx.  Control Packet Rx.  Ping Reply Tx.
20.0.0.2/
Card01/Port01  Ethernet - VM - 001  51                  51                  50

Interface stats:
Input    Punt XIPC  InputQ     XIPC         PuntQ
ClientID Drop/Total Drop/Total Cur/High/Max Cur/High/Max
--------------------------------------------------------------------------------
ipv6_icmp 0/0        0/0       0/0/1000     0/0/1000
icmp      0/50       0/0       0/15/1000    0/0/1000