Accessing the Networking Stack

The Cisco IOS XR Software serves as a networking stack for communication. This section explains how applications on IOS XR can communicate with internal processes, and with servers or outside devices.

Communication Outside Cisco IOS XR

To communicate outside Cisco IOS XR, applications use the fwdintf interface address that maps to the loopback0 interface or a configured Gigabit Ethernet interface address. For information on the various interfaces on IOS XR, see Application Hosting on the Cisco IOS XR Linux Shell.

To have an iPerf or Chef client on IOS XR communicate with its respective server outside IOS XR, you must configure an interface address as the source address on XR. The remote servers must configure this route address to reach the respective clients on IOS XR.

This section provides an example of configuring a Gigabit Ethernet interface address as the source address for external communication.

Using a Gigabit Ethernet Interface for External Communication

To configure a GigE interface on IOS XR for external communication, use these steps:

  1. Configure a GigE interface. 

    RP/0/RP0/CPU0:ios(config)# interface GigabitEthernet 0/0/0/1 
RP/0/RP0/CPU0:ios(config-if)# ipv4 address 192.57.43.10 255.255.255.0
RP/0/RP0/CPU0:ios(config-if)# no shut 
RP/0/RP0/CPU0:ios(config-if)# commit
Fri Oct 30 07:51:14.785 UTC
RP/0/RP0/CPU0:ios(config-if)# exit
RP/0/RP0/CPU0:ios(config)# exit

  2. Verify whether the configured interface is up and operational on IOS XR. 

    RP/0/RP0/CPU0:ios# show ipv4 interface brief
Fri Oct 30 07:51:48.996 UTC

Interface                      IP-Address      Status                Protocol
Loopback0                      1.1.1.1         Up                    Up      
Loopback1                      8.8.8.8         Up                    Up      
GigabitEthernet0/0/0/0         192.164.168.10  Up                    Up      
GigabitEthernet0/0/0/1         192.57.43.10    Up                    Up      
GigabitEthernet0/0/0/2         unassigned      Shutdown              Down    
MgmtEth0/RP0/CPU0/0            192.168.122.197 Up                    Up      
RP/0/RP0/CPU0:ios#

  3. Enter the Linux bash shell and verify if the configured interface is up and running. 

    

/* If you are using Cisco IOS XR Version 6.0.0, run the following command */
RP/0/RP0/CPU0:ios# run ip netns exec tpnns bash

/* If you are using Cisco IOS XR Version 6.0.2, run the following command */
RP/0/RP0/CPU0:ios# bash


[xr-vm_node0_RP0_CPU0:~]$ ifconfig
Gi0_0_0_0 Link encap:Ethernet  HWaddr 52:46:04:87:19:3c  
          inet addr:192.164.168.10  Mask:255.255.255.0
          inet6 addr: fe80::5046:4ff:fe87:193c/64 Scope:Link
          UP RUNNING NOARP MULTICAST  MTU:1514  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:210 (210.0 B)

Gi0_0_0_1 Link encap:Ethernet  HWaddr 52:46:2e:49:f6:ff  
          inet addr:192.57.43.10  Mask:255.255.255.0
          inet6 addr: fe80::5046:2eff:fe49:f6ff/64 Scope:Link
          UP RUNNING NOARP MULTICAST  MTU:1514  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:210 (210.0 B)

Mg0_RP0_CPU0_0 Link encap:Ethernet  HWaddr 52:46:12:7a:88:41  
          inet addr:192.168.122.197  Mask:255.255.255.0
          inet6 addr: fe80::5046:12ff:fe7a:8841/64 Scope:Link
          UP RUNNING NOARP MULTICAST  MTU:1514  Metric:1
          RX packets:3 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:294 (294.0 B)  TX bytes:504 (504.0 B)

fwd_ew    Link encap:Ethernet  HWaddr 00:00:00:00:00:0b  
          inet6 addr: fe80::200:ff:fe00:b/64 Scope:Link
          UP RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:4 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:1 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:392 (392.0 B)  TX bytes:532 (532.0 B)

fwdintf   Link encap:Ethernet  HWaddr 00:00:00:00:00:0a  
          inet6 addr: fe80::200:ff:fe00:a/64 Scope:Link
          UP RUNNING NOARP MULTICAST  MTU:1482  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2 errors:0 dropped:1 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:140 (140.0 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:1500  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:672 (672.0 B)  TX bytes:672 (672.0 B)

lo:0      Link encap:Local Loopback  
          inet addr:1.1.1.1  Mask:255.255.255.255
          UP LOOPBACK RUNNING  MTU:1500  Metric:1

  4. Exit the Linux bash shell and configure the GigE interface as the source address for external communication. 

    
[xr-vm_node0_RP0_CPU0:~]$ exit

RP/0/RP0/CPU0:ios# config 
Fri Oct 30 08:55:17.992 UTC
RP/0/RP0/CPU0:ios(config)# tpa address-family ipv4 update-source gigabitEthernet 0/0/0/1
RP/0/RP0/CPU0:ios(config)# commit
Fri Oct 30 08:55:38.795 UTC

    Note

    By default, the fwdintf interface maps to the loopback0 interface for external communication. This is similar to binding a routing process or router ID to the loopback0 interface. When you use the tpa address-family ipv4 update-source command to bind the fwdintf interface to a Gigabit Ethernet interface, network connectivity can be affected if the interface goes down.

  5. Enter the Linux bash shell and verify whether the GigE interface address is used by the fwdintf interface for external communication. 

    
/* If you are using Cisco IOS XR Version 6.0.0, run the following command */
RP/0/RP0/CPU0:ios# run ip netns exec tpnns bash

/* If you are using Cisco IOS XR Version 6.0.2, run the following command */
RP/0/RP0/CPU0:ios# bash

[xr-vm_node0_RP0_CPU0:~]$ ip route
default dev fwdintf  scope link  src 192.57.43.10 
8.8.8.8 dev fwd_ew  scope link 
192.168.122.0/24 dev Mg0_RP0_CPU0_0  proto kernel  scope link  src 192.168.122.197 
[xr-vm_node0_RP0_CPU0:~]$

External communication is successfully enabled on IOS XR.

East-West Communication for Third-Party Applications

East-West communication on IOS XR is a mechanism by which applications hosted in containers interact with native XR applications (hosted in the XR control plane).

The following figure illustrates how a third-party application hosted on IOS XR interacts with the XR Control Plane.

The application sends data to the Forwarding Information Base (FIB) of IOS XR. The application is hosted in the east portion of IOS XR, while the XR control plane is located in the west region. Therefore, this form of communication between a third-party application and the XR control plane is termed as East-West (E-W) communication.

Third-party applications such as Chef Client and Puppet Agent use this mode of communication to configure and manage containers, packages, and applications on IOS XR. In the future, this support could be extended to IOS XR, configured and managed by such third-party applications.

Figure 1. East-West Communication on IOS XR


For a third-party application to communicate with IOS XR, the Loopback1 interface must be configured. This is explained in the following procedure.

  1. Configure the Loopback1 interface on IOS XR. 

    RP/0/RP0/CPU0:ios(config)# interface Loopback1 
RP/0/RP0/CPU0:ios(config-if)# ipv4 address 8.8.8.8/32        
RP/0/RP0/CPU0:ios(config-if)# no shut
RP/0/RP0/CPU0:ios(config-if)# commit
RP/0/RP0/CPU0:ios(config-if)# exit
RP/0/RP0/CPU0:ios(config)#

  2. Verify the creation of the Loopback1 interface. 

    RP/0/RP0/CPU0:ios# show ipv4 interface brief
Thu Nov 12 10:01:00.874 UTC

Interface                      IP-Address      Status                Protocol
Loopback0                      1.1.1.1         Up                    Up      
Loopback1                      8.8.8.8         Up                    Up      
GigabitEthernet0/0/0/0         192.164.168.10  Up                    Up      
GigabitEthernet0/0/0/1         192.57.43.10    Up                    Up      
GigabitEthernet0/0/0/2         unassigned      Shutdown              Down    
MgmtEth0/RP0/CPU0/0            192.168.122.197 Up                    Up      
RP/0/RP0/CPU0:ios#

  3. Enter the third-party network namespace or global VRF depending on the version of IOS XR version you are using for your network. 

    /* If you are using Cisco IOS XR Version 6.0.0, run the following command */
RP/0/RP0/CPU0:ios# run ip netns exec tpnns bash

/* If you are using Cisco IOS XR Version 6.0.2, run the following command */
RP/0/RP0/CPU0:ios# bash

  4. Verify whether the Loopback1 interface address has been mapped to the E-W interface. 

    [xr-vm_node0_RP0_CPU0:~]$ ip route
default dev fwdintf  scope link  src 192.57.43.10 
8.8.8.8 dev fwd_ew  scope link 
192.168.122.0/24 dev Mg0_RP0_CPU0_0  proto kernel  scope link  src 192.168.122.197 
[xr-vm_node0_RP0_CPU0:~]$

Configuring Multiple VRFs for Application Hosting

Cisco IOS XR Release 6.3.1 supports the configuration of multiple VRFs. The applications hosted in third-party LXCs can communicate with VRFs configured on XR, after east-west communication has been enabled on the VRFs.

This section describes the configuration for creating mulitple VRFs, and enabling east-west communication between the applications and the VRFs.

Configuration Procedure

Use the following steps to configure multiple VRFs for use on Cisco IOS XR.

  1. Configure VRFs on XR.

    
RP/0/RP0/CPU0:ios(config)# vrf purple
RP/0/RP0/CPU0:ios(config-vrf)# address-family ipv4
RP/0/RP0/CPU0:ios(config-vrf)# address-family ipv6
RP/0/RP0/CPU0:ios(config-vrf)# exit

RP/0/RP0/CPU0:ios(config)# vrf green
RP/0/RP0/CPU0:ios(config-vrf)# address-family ipv4
RP/0/RP0/CPU0:ios(config-vrf)# address-family ipv6
RP/0/RP0/CPU0:ios(config-vrf)# exit


    
RP/0/RP0/CPU0:ios(config)# telnet vrf purple ipv4 server max-servers 2
RP/0/RP0/CPU0:ios(config)# telnet vrf purple ipv6 server max-servers 2
RP/0/RP0/CPU0:ios(config)# telnet vrf green ipv4 server max-servers 2
RP/0/RP0/CPU0:ios(config)# telnet vrf green ipv6 server max-servers 2
RP/0/RP0/CPU0:ios(config)# telnet ipv4 server max-servers 2
RP/0/RP0/CPU0:ios(config)# telnet ipv6 server max-servers 2

  2. Configure the interfaces to be used with the VRFs.

    RP/0/RP0/CPU0:ios(config)# interface loopback1
RP/0/RP0/CPU0:ios(config-if)# vrf purple
RP/0/RP0/CPU0:ios(config-if)# ipv4 address 1.1.1.1 255.255.255.0
RP/0/RP0/CPU0:ios(config-if)# ipv6 address 10::1/64
RP/0/RP0/CPU0:ios(config-if)# exit

RP/0/RP0/CPU0:ios(config)# interface loopback2
RP/0/RP0/CPU0:ios(config-if)# vrf purple
RP/0/RP0/CPU0:ios(config-if)# ipv4 address 2.2.2.2 255.255.255.0
RP/0/RP0/CPU0:ios(config-if)# ipv6 address 20::1/64
RP/0/RP0/CPU0:ios(config-if)# exit

RP/0/RP0/CPU0:ios(config)# interface loopback3
RP/0/RP0/CPU0:ios(config-if)#vrf green
RP/0/RP0/CPU0:ios(config-if)# ipv4 address 3.3.3.3 255.255.255.0
RP/0/RP0/CPU0:ios(config-if)# ipv6 address 30::1/64
RP/0/RP0/CPU0:ios(config-if)# exit

RP/0/RP0/CPU0:ios(config)# interface loopback4
RP/0/RP0/CPU0:ios(config-if)# vrf green
RP/0/RP0/CPU0:ios(config-if)# ipv4 address 4.4.4.4 255.255.255.0
RP/0/RP0/CPU0:ios(config-if)# ipv6 address 40::1/64
RP/0/RP0/CPU0:ios(config-if)# exit

RP/0/RP0/CPU0:ios(config)# interface mgmtEth 0/RP0/CPU0/0
RP/0/RP0/CPU0:ios(config-if)# vrf purple
RP/0/RP0/CPU0:ios(config-if)# ipv4 address dhcp
RP/0/RP0/CPU0:ios(config-if)# exit

RP/0/RP0/CPU0:ios(config)# interface GigabitEthernet 0/0/0/0
RP/0/RP0/CPU0:ios(config-if)# vrf purple
RP/0/RP0/CPU0:ios(config-if)# ipv4 address 10.20.30.40 255.255.255.0
RP/0/RP0/CPU0:ios(config-if)# ipv6 address 24::1/64
RP/0/RP0/CPU0:ios(config-if)# exit

RP/0/RP0/CPU0:ios(config)# interface gigabitEthernet 0/0/0/1
RP/0/RP0/CPU0:ios(config-if)# vrf green
RP/0/RP0/CPU0:ios(config-if)# ipv4 address 40.30.20.10 255.255.255.0
RP/0/RP0/CPU0:ios(config-if)# ipv6 address 22::1/64
RP/0/RP0/CPU0:ios(config-if)# exit
RP/0/RP0/CPU0:ios(config)# commit
Fri Sep  1 12:04:37.796 UTC

  3. Configure TPA VRFs.

    RP/0/RP0/CPU0:ios(config)# tpa
RP/0/RP0/CPU0:ios(config-tpa)# vrf purple
RP/0/RP0/CPU0:ios(config-tpa-vrf)# east-west loopback1
RP/0/RP0/CPU0:ios(config-tpa-vrf)# east-west loopback2
RP/0/RP0/CPU0:ios(config-tpa-vrf)# address-family ipv4
RP/0/RP0/CPU0:ios(config-tpa-vrf-afi)# update-source GigabitEthernet 0/0/0/0
RP/0/RP0/CPU0:ios(config-tpa-vrf-afi)# exit
RP/0/RP0/CPU0:ios(config-tpa-vrf)# address-family ipv6
RP/0/RP0/CPU0:ios(config-tpa-vrf-afi)# update-source Gigabitethernet 0/0/0/0
RP/0/RP0/CPU0:ios(config-tpa-vrf-afi)# exit
RP/0/RP0/CPU0:ios(config-tpa-vrf)# exit


    RP/0/RP0/CPU0:ios(config-tpa)# vrf green
RP/0/RP0/CPU0:ios(config-tpa-vrf)# east-west loopback3
RP/0/RP0/CPU0:ios(config-tpa-vrf)# east-west loopback4
RP/0/RP0/CPU0:ios(config-tpa-vrf)# address-family ipv4
RP/0/RP0/CPU0:ios(config-tpa-vrf-afi)# update-source GigabitEthernet 0/0/0/1
RP/0/RP0/CPU0:ios(config-tpa-vrf-afi)# exit
RP/0/RP0/CPU0:ios(config-tpa-vrf)# address-family ipv6
RP/0/RP0/CPU0:ios(config-tpa-vrf-afi)# update-source Gigabitethernet 0/0/0/1
RP/0/RP0/CPU0:ios(config-tpa-vrf-afi)# exit
RP/0/RP0/CPU0:ios(config-tpa-vrf)# exit
RP/0/RP0/CPU0:ios(config-tpa)# exit

  4. Validate the configuration.

    RP/0/RP0/CPU0:ios(config)# show run
Fri Sep  1 12:06:35.596 UTC
...
vrf purple
address-family ipv4
address-family ipv6
vrf green
address-family ipv4
address-family ipv6

telnet vrf green ipv4 server max-servers 2
telnet vrf green ipv6 server max-servers 2
telnet vrf purple ipv4 server max-servers 2
telnet vrf purple ipv6 server max-servers 2
telnet vrf default ipv4 server max-servers 2
telnet vrf default ipv6 server max-servers 2
...
!
tpa
 vrf purple
  east-west loopback1
  east-west loopback2
  address-family ipv4
   update-source GigabitEthernet0/0/0/0
 !
  address-family ipv6
   update-source GigabitEthernet0/0/0/0
 !

 vrf green
  east-west loopback3
  east-west loopback4
  address-family ipv4
   update-source GigabitEthernet0/0/0/1
 !
  address-family ipv6
   update-source GigabitEthernet0/0/0/1
 !
!
interface loopback1
 vrf purple
 ipv4 address 1.1.1.1 255.255.255.0
 ipv6 address 10::1/64
!
interface loopback2
 vrf purple
 ipv4 address 2.2.2.2 255.255.255.0
 ipv6 address 20::1/64
!
interface loopback3
 vrf green
 ipv4 address 3.3.3.3 255.255.255.0
 ipv6 address 30::1/64
!
interface loopback4
 vrf green
 ipv4 address 4.4.4.4 255.255.255.0
 ipv6 address 40::1/64
!
interface MgmtEth0/RP0/CPU0/0
 vrf purple
 ipv4 address dhcp
!
router static
 address-family ipv4 unicast
  0.0.0.0/0 MgmtEth0/RP0/CPU0/0 10.0.2.2
 !
!

  5. To verify if the VRFs are accessible in the IOS XR Linux shell, you can use the following commands for the respective VRF.

    
RP/0/RP0/CPU0:ios# bash vrf purple -c telnet 1.1.1.1
RP/0/RP0/CPU0:ios# bash vrf purple -c telnet 2.2.2.2
RP/0/RP0/CPU0:ios# bash vrf purple -c telnet 10::1
RP/0/RP0/CPU0:ios# bash vrf purple -c telnet 20::1
RP/0/RP0/CPU0:ios# bash vrf green -c telnet 3.3.3.3
RP/0/RP0/CPU0:ios# bash vrf green -c telnet 4.4.4.4
RP/0/RP0/CPU0:ios# bash vrf green -c telnet 30::1
RP/0/RP0/CPU0:ios# bash vrf green -c telnet 40::1

You have successfully configured multiple VRFs for use on Cisco IOS XR.