Packet I/O Functionality and Hosting Applications

Setting up Application Hosting Environment

This section illustrates how, with the Packet I/O functionality, you can use Linux applications to manage communication with the IOS XR interfaces. It describes how the OS environment must be set up to establish packet I/O communication with hosted applications.


Note

This section is applicable only for the NCS 540 L platform, which runs the LNT Linux packet I/O for third-party applications. The configuration commands are run in the linux-networking submode.

Verify Reachability of IOS XR and Packet I/O Infrastructure

Feature Name

Release Information

Description

Interfaces configured on IOS XR are programmed into the Linux kernel. These interfaces allow Linux applications to run as if they were running on a regular Linux system. This packet I/O capability ensures that off-the-shelf Linux applications can be run alongside IOS XR, allowing operators to use their existing tools and automate deployments with IOS XR.

The IP address on the Linux interfaces, MTU settings, MAC address are inherited from the corresponding settings of the IOS XR interface. Accessing the global VRF network namespace ensures that when you issue the bash command, the default or the global VRF in IOS XR is reflected in the kernel. This ensures default reachability based on the routing capabilities of IOS XR and the packet I/O infrastructure.

You can run bash commands at the IOS XR router prompt to view the interfaces and IP addresses stored in global VRF. When you access the Cisco IOS XR Linux shell, you directly enter the global VRF.

Procedure

Step 1

From your Linux box, access the IOS XR console through SSH, and log in.

Example:

cisco@host:~$ ssh root@192.168.122.188
root@192.168.122.188's password:
Router#

Step 2

View the ethernet interfaces on IOS XR.

Example:

Router#show ip interface brief
Interface IP-Address Status Protocol Vrf-Name
FourHundredGigE0/0/0/0 unassigned Shutdown Down default
FourHundredGigE0/0/0/1 unassigned Shutdown Down default
FourHundredGigE0/0/0/2 unassigned Shutdown Down default
FourHundredGigE0/0/0/3 unassigned Shutdown Down default
FourHundredGigE0/0/0/4 unassigned Shutdown Down default
FourHundredGigE0/0/0/5 unassigned Shutdown Down default
FourHundredGigE0/0/0/6 unassigned Shutdown Down default
FourHundredGigE0/0/0/7 unassigned Shutdown Down default
FourHundredGigE0/0/0/8 unassigned Shutdown Down default
FourHundredGigE0/0/0/9 unassigned Shutdown Down default
FourHundredGigE0/0/0/10 unassigned Shutdown Down default
FourHundredGigE0/0/0/11 unassigned Shutdown Down default
FourHundredGigE0/0/0/12 unassigned Shutdown Down default
FourHundredGigE0/0/0/13 unassigned Shutdown Down default
FourHundredGigE0/0/0/14 unassigned Shutdown Down default
FourHundredGigE0/0/0/15 unassigned Shutdown Down default
FourHundredGigE0/0/0/16 unassigned Shutdown Down default
FourHundredGigE0/0/0/17 unassigned Shutdown Down default
FourHundredGigE0/0/0/18 unassigned Shutdown Down default
FourHundredGigE0/0/0/19 unassigned Shutdown Down default
FourHundredGigE0/0/0/20 unassigned Shutdown Down default
FourHundredGigE0/0/0/21 unassigned Shutdown Down default
FourHundredGigE0/0/0/22 unassigned Shutdown Down default
FourHundredGigE0/0/0/23 unassigned Shutdown Down default
HundredGigE0/0/0/24 10.1.1.10 Up Up default
HundredGigE0/0/0/25 unassigned Shutdown Down default
HundredGigE0/0/0/26 unassigned Shutdown Down default
HundredGigE0/0/0/27 unassigned Shutdown Down default
HundredGigE0/0/0/28 unassigned Shutdown Down default
HundredGigE0/0/0/29 unassigned Shutdown Down default
HundredGigE0/0/0/30 unassigned Shutdown Down default
HundredGigE0/0/0/31 unassigned Shutdown Down default
HundredGigE0/0/0/32 unassigned Shutdown Down default
HundredGigE0/0/0/33 unassigned Shutdown Down default
HundredGigE0/0/0/34 unassigned Shutdown Down default
HundredGigE0/0/0/35 unassigned Shutdown Down default
MgmtEth0/RP0/CPU0/0 192.168.122.22 Up Up default

Note

 

Use the ip addr show or ip link show commands to view all corresponding interfaces in Linux. The IOS XR interfaces that are admin-down state also reflects a Down state in the Linux kernel.

Step 3

Check the IP and MAC addresses of the interface that is in Up state. Here, interfaces HundredGigE0/0/0/24 and MgmtEth0/RP0/CPU0/0 are in the Up state.

Example:

Router#show interfaces HundredGigE0/0/0/24
...
HundredGigE0/0/0/24 is up, line protocol is up
Interface state transitions: 4
Hardware is HundredGigE0/0/0/24, address is 5246.e8a3.3754 (bia
5246.e8a3.3754)
Internet address is 10.1.1.1/24
MTU 1514 bytes, BW 1000000 Kbit (Max: 1000000 Kbit)
reliability 255/255, txload 0/255, rxload 0/255
Encapsulation ARPA,
Duplex unknown, 1000Mb/s, link type is force-up
output flow control is off, input flow control is off
loopback not set, 
Last link flapped 01:03:50
ARP type ARPA, ARP timeout 04:00:00
Last input 00:38:45, output 00:38:45
Last clearing of "show interface" counters never
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
12 packets input, 1260 bytes, 0 total input drops
0 drops for unrecognized upper-level protocol
Received 2 broadcast packets, 0 multicast packets
0 runts, 0 giants, 0 throttles, 0 parity
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
12 packets output, 1224 bytes, 0 total output drops
Output 1 broadcast packets, 0 multicast packets

Step 4

Verify that the bash command runs in global VRF to view the network interfaces.

Example:

Router#bash -c ifconfig 
Hu0_0_0_24 Link encap:Ethernet HWaddr 78:e7:e8:d3:20:c0
inet addr:10.1.1.10 Bcast:0.0.0.0 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:360 (360.0 B) TX bytes:0 (0.0 B)
Mg0_RP0_CPU0_0 Link encap:Ethernet HWaddr 54:00:00:00:bd:49
inet addr:192.168.122.22 Bcast:0.0.0.0 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:3859 errors:0 dropped:0 overruns:0 frame:0
TX packets:1973 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2377782 (2.2 MiB) TX bytes:593602 (579.6 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:242 errors:0 dropped:0 overruns:0 frame:0
TX packets:242 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:12100 (11.8 KiB) TX bytes:12100 (11.8 KiB)
to_xr Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:0 (0.0 B) TX bytes:60 (60.0 B)

The to_xr interface indicates access to the global VRF.

Step 5

Access the Linux shell.

Example:

Router#bash
[ios:~]$

Step 6

(Optional) View the IP routes used by the to_xr interfaces.

Example:

[ios:~]$ip route
default dev to_xr scope link metric 2048
6.1.0.0/16dev Mg0_RP0_CPU0_0 proto kernel scope link src 6.1.22.41
20.1.0.0/16dev Hu0_0_0_0 proto kernel scope link src 20.1.1.1
20.2.0.0/16dev Hu0_0_0_20 proto kernel scope link src 20.2.1.1
30.1.0.0/24dev BE500 proto kernel scope link src 30.1.0.1
172.17.0.0/16dev docker0 proto kernel scope link src 172.17.0.1linkdown

Note

 

You can also enter the global VRF directly after logging into IOS XR using the run ip netns exec vrf-default bash command.

Programme Routes in the Kernel

The basic routes required to allow applications to send or receive traffic can be programmed into the kernel. The Linux network stack that is part of the kernel is used by normal Linux applications to send/receive packets. In an IOS XR stack, IOS XR acts as the network stack for the system. Therefore to allow the Linux network stack to connect into and use the IOS XR network stack, basic routes must be programmed into the Linux Kernel.

Procedure

Step 1

View the routes from the bash shell.

Example:

[ios:~]$ip route
default dev to_xr scope link src 10.1.1.10 metric 2048
10.1.1.0/24 dev Hu0_0_0_24 proto kernel scope link src 10.1.1.10
192.168.122.0/24 dev Mg0_RP0_CPU0_0 proto kernel scope link src 192.168.122.22

Step 2

Programme the routes in the kernel.

Two types of routes can be programmed in the kernel:

  • Default Route: The default route sends traffic destined to unknown subnets out of the kernel using a special to_xr interface. This interface sends packets to IOS XR for routing using the routing state in XR Routing Information Base (RIB) or Forwarding Information Base (FIB). The to_xr interface does not have an associated IP address. In Linux, most applications expect the outgoing packets to use the IP address of the outgoing interface as the source IP address.

    With the to_xr interface, because there is no IP address, a source hint is required. The source hint can be changed to use the IP address another physical interface IP or loopback IP address. In the following example, the source hint is set to 10.1.1.10, which is the IP address of the Hu0_0_0_24 interface. To use the Management port IP address, change the source hint: 

    Router#bash

[ios:~]$ip route replace default dev to_xr scope link src 192.168.122.22 metric 2048

[ios:~]$ip route
default dev to_xr scope link src 192.168.122.22 metric 2048
10.1.1.0/24 dev Hu0_0_0_24 proto kernel scope link src 10.1.1.10
192.168.122.0/24 dev Mg0_RP0_CPU0_0 proto kernel scope link src 192.168.122.22

    With this updated source hint, any default traffic exiting the system uses the Management port IP address as the source IP address.

  • Local or Connected Routes: The routes are associated with the subnet configured on interfaces. For example, the 10.1.1.0/24 network is associated with the Hu0_0_0_24 interface, and the 192.168.122.0/24 subnet is associated with the Mg0_RP0_CPU0 interface .

Configure VRFs in the Kernel

VRFs configured in IOS XR are automatically synchronized to the kernel. In the kernel, the VRFs appear as network namespaces (netns). For every globally-configured VRF, a Linux network namespace is created. With this capability it is possible to isolate Linux applications or processes into specific VRFs like an out-of-band management VRF and open-up sockets or send or receive traffic only on interfaces in that VRF.

Every VRF, when synchronized with the Linux kernel, is programmed as a network namespace with the same name as a VRF but with the string vrf prefixed to it. The default VRF in IOS XR has the name default. This name gets programmed as vrf-default in the Linux kernel.

The following example shows how to configure a custom VRF blue:

Procedure

Step 1

Identify the current network namespace or VRF.

Example:

[ios:~]$ip netns identify $$
vrf-default
global-vrf

Step 2

Configure a custom VRF blue.

Example:

Router#conf t

Router(config)#vrf blue
Router(config-vrf)#commit

Step 3

Verify that the VRF blue is configured in IOS XR.

Example:

Router#show run vrf
vrf blue
!

Step 4

Verify that the VRF blue is created in the kernel.

Example:

Router#bash

[ios:~]$ls -l /var/run/netns
total 0
-r--r--r--. 1 root root 0 Jul 30 04:17 default
-r--r--r--. 1 root root 0 Jul 30 04:17 global-vrf
-r--r--r--. 1 root root 0 Jul 30 04:17 tpnns
-r--r--r--. 1 root root 0 Aug 1 17:01 vrf-blue
-r--r--r--. 1 root root 0 Jul 30 04:17 vrf-default
-r--r--r--. 1 root root 0 Jul 30 04:17 xrnns

Step 5

Access VRF blue to launch and execute processes from the new network namespace.

Example:

[ios:~]$ip netns exec vrf-blue bash
[ios:~]$
[ios:~]$ip netns identify $$
vrf-blue
[ios:~]$
Running an ifconfig command shows only the default to-xr interface because there is no IOS XR interface in this VRF.
[ios:~]$ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
to_xr Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
[ios:~]$

Step 6

Configure an interface in the VRF blue in IOS XR. This interface will be configured automatically in the network namespace vrf-blue in the kernel.

Example:

The following example shows how to configure HundredGigE 0/0/0/24 interface in vrf-blue from IOS XR:
Router#conf t
Router(config)#int HundredGigE 0/0/0/24
Router(config-if)#no ipv4 address
Router(config-if)#vrf blue
Router(config-if)#ipv4 address 10.1.1.10/24
Router(config-if)#commit

Step 7

Verify that the HundredGigE 0/0/0/24 interface is configured in the VRF blue in IOS XR.

Example:

Router#show run int HundredGigE 0/0/0/24
interface HundredGigE0/0/0/24
vrf blue
ipv4 address 10.1.1.10 255.255.255.0
!

Step 8

Verify that the interface is configured in the VRF blue in the kernel.

Example:

Router#bash
Thu Aug 1 17:09:39.314 UTC
[ios:~]$
[ios:~]$ip netns exec vrf-blue bash
[ios:~]$
[ios:~]$ifconfig
Hu0_0_0_24 Link encap:Ethernet HWaddr 78:e7:e8:d3:20:c0
inet addr:10.1.1.10 Bcast:0.0.0.0 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
to_xr Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
[ios:~]$

Open Linux Sockets

The socket entries are programmed into the Local Packet Transport Services (LPTS) infrastructure that distributes the information through the line cards. Any packet received on a line card interface triggers an LPTS lookup to send the packet to the application opening the socket. Because the required interfaces and routes already appear in the kernel, the applications can open the sockets — TCP or UDP.

Procedure

Step 1

Verify that applications open up sockets.

Example:

Router#bash
[ios:~]$nc -l 0.0.0.0 -p 5000 &
[1] 1160
[ios:~]$
[ios:~]$netstat -nlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:5000 0.0.0.0:* LISTEN 1160/nc
tcp 0 0 0.0.0.0:57777 0.0.0.0:* LISTEN 14723/emsd
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 8875/ssh_server
tcp6 0 0 :::22 :::* LISTEN 8875/ssh_server
udp 0 0 0.0.0.0:68 0.0.0.0:* 13235/xr_dhcpcd
Active UNIX domain sockets (only servers)
Proto RefCnt Flags Type State I-Node PID/Program name Path
[ios:~]$exit
Logout
Router#
Router#show lpts pifib brief | i 5000
Thu Aug 1 17:16:00.938 UTC
IPv4 default TCP any 0/RP0/CPU0 any,5000 any
Router#

Step 2

Verify that the socket is open.

Example:

Router#show lpts pifib brief | i 5000
IPv4 default TCP any 0/RP0/CPU0 any,5000 any

Netcat starts listening on port 5000, which appears as an IPv4 TCP socket in the netstat output like a typical Linux kernel. This socket gets programmed to LPTS, creating a corresponding entry in the hardware to the lookup tcp port 5000. The incoming traffic is redirected to the kernel of the active RP where the netcat runs.

Send and Receive Traffic

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.

Manage IOS XR Interfaces through Linux

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.

Configure an Interface to be Linux-Managed

This section shows how to configure an interface to be Linux-managed.

Procedure

Step 1

Check the available exposed-interfaces in the system.

Example:
Router(config)#linux networking exposed-interfaces interface ?
  
  Bundle-Ether     Aggregated Ethernet interface(s) | short name is BE
  FiftyGigE        FiftyGigabitEthernet/IEEE 802.3 interface(s) | short name is Fi
  FortyGigE        FortyGigabitEthernet/IEEE 802.3 interface(s) | short name is Fo
  FourHundredGigE  FourHundredGigabitEthernet/IEEE 802.3 interface(s) | short name is FH
  GigabitEthernet  GigabitEthernet/IEEE 802.3 interface(s) | short name is Gi
  HundredGigE      HundredGigabitEthernet/IEEE 802.3 interface(s) | short name is Hu
  Loopback         Loopback interface(s) | short name is Lo
  MgmtEth          Ethernet/IEEE 802.3 interface(s) | short name is Mg
  TenGigE          TenGigabitEthernet/IEEE 802.3 interface(s) | short name is Te
  TwentyFiveGigE   TwentyFiveGigabitEthernet/IEEE 802.3 interface(s) | short name is TF
  TwoHundredGigE   TwoHundredGigabitEthernet/IEEE 802.3 interface(s) | short name is TH

Step 2

Configure the interface to be managed by Linux.

Example:
The following example shows how to configure a HundredGigE interface to be managed by Linux:
Router#configure
Router(config)#linux networking exposed-interfaces interface HundredGigE 0/0/0/24 linux-managed
Router(config-exi-if)#commit

Step 3

View the interface details and the VRF.

Example:
The following example shows the information for HundredGigE interface:
Router#show run interface HundredGigE0/0/0/24
interface HundredGigE0/0/0/24
mtu 4110
vrf blue
ipv4 mtu 4096
ipv4 address 10.1.1.10 255.255.255.0
ipv6 mtu 4096
ipv6 address fe80::7ae7:e8ff:fed3:20c0 link-local
!

Step 4

Verify the configuration in XR.

Example:
The following example shows the configuration for HundredGigE interface:
Router#show running-config linux networking

linux networking
 exposed-interfaces
  interface HundredGigE0/0/0/24 linux-managed
  !
 !
!

Step 5

Verify the configuration from Linux.

Example:
The following example shows the configuration for HundredGigE interface:
Router#bash
Router:Aug 1 17:40:02.873 UTC: bash_cmd[67805]: %INFRA-INFRA_MSG-5-RUN_LOGIN : User vagrant logged into shell from vty0

[ios:~]$ip netns exec vrf-blue bash

[ios:~]$ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
to_xr Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

[ios:~]$ifconfig -a
Hu0_0_0_24 Link encap:Ethernet HWaddr 78:e7:e8:d3:20:c0
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
to_xr Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

Configure New IP address on the Interface in Linux

This section shows how to configure a new IP address on the Linux-managed interface.

Procedure

Step 1

Configure the IP address on the interface.

Example:
[ios:~]$ip addr add 10.1.1.10/24 dev Hu0_0_0_24
[ios:~]$Router:Aug 1 17:41:11.546 UTC: xlncd[253]: %MGBL-CONFIG-6-DB_COMMIT : Configuration
committed by user 'system'. Use 'show configuration commit changes 1000000021' to view the changes.

Step 2

Verify that the new IP address is configured.

Example:
[ios:~]$ifconfig Hu0_0_0_24
Hu0_0_0_24 Link encap:Ethernet HWaddr 78:e7:e8:d3:20:c0
inet addr:10.1.1.10 Bcast:0.0.0.0 Mask:255.255.255.0
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

Configure Custom MTU Setting

This section shows how to bring up the interface and configure a custom MTU in a Linux-managed interface.

Procedure

Step 1

Configure the MTU setting.

Example:
[ios:~]$ifconfig Hu0_0_0_24 up

[ios:~]$Router:Aug 1 17:41:54.824 UTC: ifmgr[266]: %PKT_INFRA-LINK-3-UPDOWN : Interface
HundredGigE0/0/0/24, changed state to Down
Router:Aug 1 17:41:54.824 UTC: ifmgr[266]: %PKT_INFRA-LINEPROTO-5-UPDOWN : Line protocol on
Interface HundredGigE0/0/0/24, changed state to Down
Router:Aug 1 17:41:56.448 UTC: xlncd[253]: %MGBL-CONFIG-6-DB_COMMIT : Configuration committed by
user 'system'. Use 'show configuration commit changes 1000000022' to view the changes.
Router:Aug 1 17:41:56.471 UTC: ifmgr[266]: %PKT_INFRA-LINK-3-UPDOWN : Interface
HundredGigE0/0/0/24, changed state to Up
Router:Aug 1 17:41:56.484 UTC: ifmgr[266]: %PKT_INFRA-LINEPROTO-5-UPDOWN : Line protocol on
Interface HundredGigE0/0/0/24, changed state to Up
Router:Aug 1 17:41:58.493 UTC: xlncd[253]: %MGBL-CONFIG-6-DB_COMMIT : Configuration committed by
user 'system'. Use 'show configuration commit changes 1000000023' to view the changes.

[ios:~]$
[ios:~]$ ip link set dev Hu0_0_0_24 mtu 4096
[ios:~]$
[ios:~]$Router:Aug 1 17:42:46.830 UTC: xlncd[253]: %MGBL-CONFIG-6-DB_COMMIT : Configuration
committed by user 'system'. Use 'show configuration commit changes 1000000024' to view the changes.

Step 2

Verify that the MTU setting has been updated in Linux.

Example:
[ios:~]$ifconfig
Hu0_0_0_24 Link encap:Ethernet HWaddr 78:e7:e8:d3:20:c0
inet addr:10.1.1.10 Bcast:0.0.0.0 Mask:255.255.255.0
inet6 addr: fe80::7ae7:e8ff:fed3:20c0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:4096 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:648 (648.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
to_xr Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

Step 3

Check the effect on the IOS XR configuration with the change in MTU setting on this interface.

Example:
Router#show running-config int HundredGigE0/0/0/24
interface HundredGigE0/0/0/24
 mtu 4110
  vrf blue
  ipv4 mtu 4096
  ipv4 address 10.1.1.10 255.255.255.0
  ipv6 mtu 4096
  ipv6 address fe80::7ae7:e8ff:fed3:20c0 link-local
  !
 !
!
Router#
Router#show ip int br | i HundredGigE0/0/0/24
HundredGigE0/0/0/24 10.1.1.10 Up Up blue

The output indicates that the interface acts as a regular Linux interface, and IOS XR configuration receives inputs from Linux.

Configure Traffic Protection for Linux Networking

Traffic protection provides a mechanism to configure Linux firewalls using IOS XR configuration. These rules can be used to restrict traffic to Linux applications. You can restrict traffic to Linux applications using native Linux firewalls or configuring IOS XR Linux traffic protection. It is not recommended to use both mechanisms at the same time. Any combination of remote address, local address and ingress interface can be specified as rules to either allow or deny traffic. However, at least one parameter must be specified for the traffic protection rule to be valid.


Note

If traffic is received on a protocol or port combination that has no traffic protection rules configured, then all traffic is allowed by default.

This example explains how to configure a traffic protection rule on IOS XR to deny all traffic on port 999 except for traffic arriving on interface HundredGigE0/0/0/25.

Procedure

Step 1

Configure traffic protection rules.

Example:

Router(config)#linux networking vrf default address-family ipv4 protection protocol 
tcp local-port 999 default-action deny permit hundredgigE0/0/0/25
Router(config)#commit

where —

  • address-family: Configuration for a particular IPv4 or IPv6 address family.

  • protection: Configure traffic protection for Linux networking.

  • protocol: Select the supported protocol - TCP or UDP.

  • local-port: L4 port number to specify traffic protection rules for Linux networking.

  • port number: Port number ranges from 1 to 65535 or all ports.

  • default-action: Default action to take for packets matching this traffic protection service.

  • deny: Drop packets for this service.

  • permit: Permit packets to reach Linux application for this service.

Step 2

Verify that the traffic protection rule is applied successfully.

Example:

Router(config)#show run linux networking
linux networking
 vrf default
  address-family ipv4
   protection
    protocol tcp local-port 999 default-action deny
     permit interface HundredGigE0/0/0/25
     !
    !
   !
 !

Synchronize Statistics Between IOS XR and Linux

This example shows how the bundle-ether interface packet statistics are synchronized between IOS XR and Linux. The packet and byte counters maintained by Linux for IOS XR interfaces display only the traffic sourced in Linux. You can configure to periodically synchronize these counters with the IOS XR statistics for the interfaces.

Procedure

Step 1

Configure the statistics synchronization including the direction and synchronization interval.

Example:

The following example shows statistics synchronization in global configuration:
Router(config)#linux networking statistics-synchronization from-xr 
every 30s

Example:

The following example shows statistics synchronization in exposed-interface configuration:
Router(config)#linux networking exposed-interfaces interface 
bundle-ether 1 statistics-synchronization from-xr every 10s

where —

  • from-xr: The direction indicating that the interface packet statistics will be pushed from IOS XR to the Linux kernel.

  • every: Shows the frequency at which to synchronize statistics. The intervals supported for global configuration are 30s and 60s. The intervals supported for exposed interfaces are 5s, 10s, 30s or 60s. The interval s is in seconds.

Step 2

Verify that the statistics synchronization is applied successfully on IOS XR.

Example:

Router#show run linux networking 
linux networking
 vrf default
  address-family ipv4
   protection
   protocol tcp local-port all default-action deny 
    permit interface bundle-ether 1  
    !
   !
  ! 
 !
exposed-interfaces
 interface bundle-ether 1 linux-managed
  statistics-synchronization from-xr every 10s
  !
 !
!

For troubleshooting purposes, use the show tech-support linux networking command to display debugging information.

Hosting an Application in Docker Containers

This section provides the procedure for hosting an application in docker containers.

The iPerf application is used as an example to demonstrate the hosting at a server and a client router.

Verify Reachability of IOS XR and Packet I/O Infrastructure on the router that hosts the iPerf application. You can enable the following Packet I/O functionalities on the server and client routers prior to hosting the iPerf application in docker containers, for additional features on the routers:

  • Program Routes in the Kernel—to send or receive traffic to a remote network using a specific interface.

  • Configure VRFs in the Kernel—to run the iperf application in a non-default VRF.

  • Configure Traffic Protection for Linux Networking—to secure the router by restricting access to the router on which the iperf application is hosted.

You build the docker image of the application following the standard docker build procedures. The docker image of any application (for example, iPerf) is built only once, after which, that docker image can be copied to other devices where the application can be hosted in docker containers.

Docker Operations

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

Commands for Hosting Applications

  • Pull or Load the image: This function copies a docker image to a device.

    • Pull—

      The following command pulls the Docker image from a local docker registry. Ensure that the registry is accessible from the router.
      [ios:~]$docker pull ufi-lnx:5001/alpine
! Here ufi-lnx is the docker registry reachable through 10.105.39.169!-->
Using default tag: latest
latest: Pulling from library/alpine
c9b1b535fdd9: Pull complete
Digest: sha256:ab00606a42621fb68f2ed6ad3c88be54397f981a7b70a79db3d1172b11c4367d
Status: Downloaded newer image for alpine:latest
[ios:~]$

      Instead of being pulled from the registry, docker images can be loaded from images saved as tar files.

    • Load—

      You save the docker image as a tar file on the build host using the docker save -o <path for generated tar file> <image name> command. You copy the tar file into the target router, using the following command:
      You copy the tar file into the target router, using the following command:
      Router#scp root@10.105.227.122:/var/www/html/alpine.tar
Tue Mar 10 02:42:38.598 UTC
Connecting to 10.105.227.122...
Password:
  Transferred 639972864 Bytes
  639972864 bytes copied in 55 sec (11606958)bytes/sec
Router#bash
Tue Mar 10 02:45:25.330 UTC
[ios:~]$docker load -i /tmp/alpine.tar
Loaded image: alpine:latest
ios:~]$docker images
REPOSITORY           TAG                 IMAGE ID            CREATED             SIZE
alpine               latest              dc721c65d296        11 days ago         622MB
[ios:~]$

  • View or List Docker Images

    [ios:~]$docker images
REPOSITORY           TAG                 IMAGE ID            CREATED             SIZE
alpine               latest              dc721c65d296        11 days ago         622MB
enipla               latest              fd31184c8c1b        6 weeks ago         581MB
[ios:~]$

  • Run Container 

    [ios:~]$docker run -it alpine bash
root@a1b719df1091:/#
root@a1b719df1091:/#
root@a1b719df1091:/#uname -a
Linux a1b719df1091 4.8.28-WR9.0.0.20_cgl#1 SMP Wed Jan 8 11:16:16 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
root@a1b719df1091:/#hostname
a1b719df1091
root@a1b719df1091:/#
[ios:~]$docker ps
CONTAINER ID        IMAGE                COMMAND             CREATED              STATUS              PORTS               NAMES
a1b719df1091        alpine               "bash"              About a minute ago   Up About a minute                       nifty_leavitt
[ios:~]$

  • Attach to a Running Container

    The docker attach command attaches the terminal to the running container and the docker exec command runs commands inside a working container. 

    [ios:~]$docker attach docker1
#bash
root@e1e1924956df:/#

    The docker exec -it my_container_id sh command executes a shell inside the container: 

    f3b-r1-pod9:/var/lib/docker/volumes]$docker exec -it 57029028609a sh
#

  • Stop Containers

    Identify the container using the docker ps command and then stop the container using the docker stop command.
    [ios:~]$docker ps
CONTAINER ID        IMAGE                COMMAND             CREATED             STATUS              PORTS               NAMES
8782d4902312        alpine               "bash"              7 minutes ago       Up 6 minutes                            hungry_keller
9bd23408d640        alpine               "bash"              17 minutes ago      Up 17 minutes                           youthful_franklin
[ios:~]$ docker stop 8782d4902312

  • Stopping All Containers

    [ios:~]$docker stop $(docker ps -a -q)

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)

Procedure for Hosting Applications in Docker Containers

  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.

Run iPerf in Docker Container

As an example of application hosting in docker container, you can install iPerf client on Router A and check its connectivity with an iPerf server installed on Router B.

This figure illustrates the topology used in this example.

Figure 1. iPerf Hosted in a Docker Container
The following steps describe how to run the iPerf server and iPerf client applications on Router A and Router B.
Before you begin
Ensure that you have configured the two routers as shown in the figure-iPerf application hosted in a Docker Container.
Procedure

Step 1

Copy the iPerf application tar file (for example, ubuntu-agnel-image.tar) on Router A.

Example:
Router#scp root@10.105.227.122:/var/www/html/ubuntu-agnel-27feb.tar $
Connecting to 10.105.227.122...
Password:
  Transferred 639972864 Bytes
  639972864 bytes copied in 55 sec (11606958)bytes/sec

Step 2

Load the docker instance on Router A by using the following command:

Example:
Router#bash
[ios:~]$docker load -i /tmp/ubuntu-agnel-27feb.tar

Step 3

View all docker images by using the following command:

Example:
[ios:~]$docker images ls
REPOSITORY           TAG                 IMAGE ID            CREATED             SIZE
ubuntu-agnel-27feb   latest              dc721c65d296        11 days ago         622MB
ubuntu-agnel-slapi   latest              fd31184c8c1b        6 weeks ago         581MB

Step 4

Repeat Steps 1 through 3 on Router B.

Step 5

Configure the application to run as iPerf server on Router A.

Example:
[ios:~]$docker run -d -it -p 601:601 ubuntu-agnel-27feb sh
[ios:~]$iperf3 -s -B 172.17.0.2

Note

 

“-p 601:601 ubuntu-agnel-27feb sh” part of the command maps the Linux port with the docker instance port. 601 on the left hand side is the Docker instance mapping port and 601 on the right hand side is the Linux kernel port.

172.17.0.2 is the IP address of the server.

Step 6

Configure the application to run as iPerf client on Router B and establish connection to iPerf server on Router A.

Example:
[ios:~]$docker run -d -it -p 601:601 ubuntu-agnel-27feb sh
[ios:~]$iperf3 -c 172.17.0.2

Note

 

“-p 601:601 ubuntu-agnel-27feb sh” part of the command maps the Linux port with the docker instance port. 601 on the left hand side is the docker instance mapping port and 601 on the right hand side is the Linux kernel port.

172.17.0.2 is the IP address of the server.

Verify the Application Hosted in the Docker Container

To verify the applications hosted in the docker containers between Router A and Router B, use the ping command to check if the connection has been established between iPerf server and iPerf client.
Procedure

From the iPerf client on Router B, ping the iPerf server on Router A by providing the physical interface IP address to verify the connection between the iPerf server and client applications.

Example:
[ios:~]$ping 172.17.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.17.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 13/21/40 ms

172.17.0.2 is the IP address of the client.