This public repo contains python code that can be used to interact with the Cisco IOS XR devices.The environment is pre-configured to access the Cisco DevNet Always-On Sandbox. You can edit the variables in the environment to point to your own IOS-XR device.
This package contains a library with the methods that are available to use over gRPC with IOS-XR boxes after 6.0.0. The API has several methods which allows a user to send simple RPC commands such as get and push using YANG and JSON.
The repo consists of two main components:
The compiled pb2 file from the proto definition. A Python module accessing the pb2 file with the library bindings.
XR devices ship with the YANG files that define the data models they support. Using a management protocol such as NETCONF or gRPC, you can programmatically query a device for the list of models it supports and retrieve the model files.
gRPC is an open-source RPC framework. It is based on Protocol Buffers (Protobuf), which is an open source binary serialization protocol. gRPC provides a flexible, efficient, automated mechanism for serializing structured data, like XML, but is smaller and simpler to use. You define the structure using protocol buffer message types in .proto files. Each protocol buffer message is a small logical record of information, containing a series of name-value pairs.
SSH in to the Always-On Sandbox IOS XR router and turn on gRPC and disable tls, below is an example configuration
grpc
port 57777
no-tls
It is recommended that this code be used with Python 3.6. It is highly recommended to leverage Python Virtual Environments (venv).
Follow these steps to create and activate a venv.
virtualenv venv --python=python3.6
source venv/bin/activate
Install the code requirements
pip install -r requirements.txt
To get all the interfaces from the Always-On Sandbox IOS-XR device, we can run this small piece of code derived from OpenConfig YANG models and serialise this as JSON. Change into the examples directory and run the following code, this uses the yang model https://github.com/YangModels/yang/blob/master/vendor/cisco/xr/653/openconfig-interfaces.yang and will print all the interface from the Always-On Sandbox IOS-XR device in the json format.
(venv)python grpc_example.py
{
"openconfig-interfaces:interfaces": {
"interface": [
{
"name": "Loopback100",
"config": {
"name": "Loopback100",
"type": "iana-if-type:softwareLoopback",
"enabled": true,
"description": "***MERGE LOOPBACK 100****"
},
"subinterfaces": {
"subinterface": [
{
"index": 0,
"openconfig-if-ip:ipv4": {
"addresses": {
"address": [
{
"ip": "1.1.1.100",
"config": {
"ip": "1.1.1.100",
"prefix-length": 32
}
}
]
}
}
}
]
}
},
[/snip]
This code uses the JSON below is based off the YANG model provided by Cisco: https://github.com/YangModels/yang/blob/master/vendor/cisco/xr/653/Cisco-IOS-XR-ipv4-bgp-cfg.yang You can walk through the hierachy using pyang, and create a JSON model similar to the example below. https://github.com/mbj4668/pyang/wiki/TreeOutput
This JSON model is for a BGP configuration. We can see that it is defining a BGP instance and a single neighbor.
{
"Cisco-IOS-XR-ipv4-bgp-cfg:bgp": {
"instance": [
{
"instance-name": "default",
"instance-as": [
{
"as": 0,
"four-byte-as": [
{
"as": 65400,
"bgp-running": [
null
],
"default-vrf": {
"global": {
"router-id": "11.1.1.10",
"global-afs": {
"global-af": [
{
"af-name": "ipv4-unicast",
"enable": [
null
],
"sourced-networks": {
"sourced-network": [
{
"network-addr": "11.1.1.0",
"network-prefix": 24
}
]
}
}
]
}
},
"bgp-entity": {
"neighbors": {
"neighbor": [
{
"neighbor-address": "11.1.1.20",
"remote-as": {
"as-xx": 0,
"as-yy": 65450
},
"neighbor-afs": {
"neighbor-af": [
{
"af-name": "ipv4-unicast",
"activate": [
null
],
"next-hop-self": true
}
]
}
}
]
}
}
}
}
]
}
]
}
]
}
}
This code uses Object-Oriented Programming (OOP). This is a programming paradigm where different components of a computer program are modeled after real-world objects. An object is anything that has some characteristics and can perform a function. All args used in the running of the code are handled using Click. Click is a Python package for creating beautiful command line interfaces in a composable way with as little code as necessary. From the examples directory run the following
(venv) grpc_xr_example$ python grpc_cfg.py --help
Usage: grpc_cfg.py [OPTIONS] COMMAND [ARGS]...
Options:
--help Show this message and exit.
Commands:
delete
get
merge
replace
Start with a get this will look at the Always-On Sandbox IOS-XR device configuration and return that BGP is not configured (note that this is an Always-On Sandbox and that other users might be using this or there could be stale conifgurations on the device),
(venv)examples$ python grpc_cfg.py get
BGP instance 'default' not active
Next, add a base BGP config using the JSON file we looked at earlier
(venv)examples$python grpc_cfg.py replace
Replace Completed
If we loggged into the Always-On Sandbox IOS-XR device, we would now see one Neighbor conifgured.
RP/0/RP0/CPU0:iosxr1#sh run router bgp
Sat Feb 13 06:01:47.321 UTC
router bgp 65400
bgp router-id 11.1.1.10
address-family ipv4 unicast
network 11.1.1.0/24
!
neighbor 11.1.1.20
remote-as 65450
address-family ipv4 unicast
next-hop-self
!
!
!
However, we can use the get function once again to see this.
(venv)examples$ python grpc_cfg.py get
{
"Cisco-IOS-XR-ipv4-bgp-cfg:bgp": {
"instance": [
{
"instance-name": "default",
"instance-as": [
{
"as": 0,
"four-byte-as": [
{
"as": 65400,
"bgp-running": [
null
],
"default-vrf": {
"global": {
"router-id": "11.1.1.10",
"global-afs": {
"global-af": [
{
"af-name": "ipv4-unicast",
"enable": [
null
],
"sourced-networks": {
"sourced-network": [
{
"network-addr": "11.1.1.0",
"network-prefix": 24
}
]
}
}
]
}
},
"bgp-entity": {
"neighbors": {
"neighbor": [
{
"neighbor-address": "11.1.1.20",
"remote-as": {
"as-xx": 0,
"as-yy": 65450
},
"neighbor-afs": {
"neighbor-af": [
{
"af-name": "ipv4-unicast",
"activate": [
null
],
"next-hop-self": true
}
]
}
}
]
}
}
}
}
]
}
]
}
]
}
}
If this worked correctly you should see the JSON file we looked at, and the response from the get should be identical Now, use a merge request to add another neighbor with the second JSON file
(venv)examples$python grpc_cfg.py merge
Merge Completed
RP/0/RP0/CPU0:iosxr1#sh run router bgp
Sat Feb 13 06:05:33.336 UTC
router bgp 65400
bgp router-id 11.1.1.10
address-family ipv4 unicast
network 11.1.1.0/24
!
neighbor 11.1.1.20
remote-as 65450
address-family ipv4 unicast
next-hop-self
!
!
neighbor 11.1.1.60
remote-as 65460
address-family ipv4 unicast
next-hop-self
!
!
!
The resulting config should be the first config plus the second, or in other words there are two neighbors defined.
This can also been seen by running the python grpc_cfg.py get file once more.
To delete the configuration we can send an empty JSON file, followed by the get file to confirm that BGP is no longer configured/active.
(venv)examples$ cat snips/bgp_delete.json
{
"Cisco-IOS-XR-ipv4-bgp-cfg:bgp": [null]
}
(venv)examples$ python grpc_cfg.py delete
Delete Completed
(venv)examples$ python grpc_cfg.py get
BGP instance 'default' not active
Network Automation Developer Advocate for Cisco DevNet. Find me here: LinkedIn / Twitter
Thanks to Karthik Kumaravel and Patrick "Bench Press 500" Rockholz for their code samples and debugging skills.
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