OpenStack VXLAN Egress_pkt_mark: A Comprehensive Guide

Introduction

OpenStack is an open-source cloud computing platform that provides Infrastructure-as-a-Service (IaaS) solutions. VXLAN (Virtual Extensible LAN) is a network virtualization technology widely used in OpenStack deployments. In this article, we will explore the concept of egress_pkt_mark in OpenStack VXLAN and provide code examples to illustrate its usage.

Understanding Egress_pkt_mark

Egress_pkt_mark is a parameter used in OpenStack VXLAN to mark the encapsulated packets with a specific value. This marking is applied to the outer Ethernet frame of the VXLAN packet. It allows the network controller to identify and handle the packets based on their marked value.

The egress_pkt_mark parameter is typically used in scenarios where advanced networking features or policies need to be applied to specific packets. For example, it can be used to prioritize certain types of traffic, apply Quality of Service (QoS) policies, or implement traffic shaping mechanisms.

VXLAN Egress_pkt_mark in OpenStack

In OpenStack, the egress_pkt_mark parameter is used in conjunction with the Neutron networking service to configure VXLAN tunnels. Neutron provides a set of APIs and agents for managing the networking resources in an OpenStack deployment.

To configure egress_pkt_mark in OpenStack VXLAN, you need to modify the ML2 configuration file (/etc/neutron/plugins/ml2/ml2_conf.ini). Locate the [ml2_type_vxlan] section and add or modify the vni_ranges parameter as follows:

[ml2_type_vxlan]
vni_ranges = <start_vni>:<end_vni>
egress_pkt_mark = <mark_value>

Replace <start_vni> and <end_vni> with the desired range of VXLAN Network Identifier (VNI) values. The egress_pkt_mark parameter should be set to the desired mark value.

Once the configuration is updated, restart the Neutron service for the changes to take effect.

Code Example

Below is a code example demonstrating the configuration of egress_pkt_mark in OpenStack VXLAN using the Python programming language:

from neutronclient.v2_0 import client

def update_vxlan_config(start_vni, end_vni, mark_value):
    neutron = client.Client(auth_url='http://<keystone_ip>:5000/v3',
                            username='<username>',
                            password='<password>',
                            project_name='<project_name>',
                            user_domain_name='default',
                            project_domain_name='default')
    
    ml2_conf = neutron.list_ml2_conf()['ml2_conf']
    vxlan_conf = ml2_conf['ml2_type_vxlan']
    
    vxlan_conf['vni_ranges'] = f"{start_vni}:{end_vni}"
    vxlan_conf['egress_pkt_mark'] = str(mark_value)
    
    neutron.update_ml2_conf(ml2_conf)

# Usage example
update_vxlan_config(1000, 2000, 1234)

In the code example, we use the neutronclient library to interact with the Neutron API. The update_vxlan_config function takes the start VNI, end VNI, and mark value as parameters and updates the ML2 configuration with the new values.

Conclusion

In this article, we explored the concept of egress_pkt_mark in OpenStack VXLAN. We learned that egress_pkt_mark is used to mark encapsulated packets with a specific value, allowing for advanced networking features and policies. We also provided a code example demonstrating the configuration of egress_pkt_mark in OpenStack VXLAN.

By utilizing egress_pkt_mark, OpenStack users can enhance their network management capabilities and implement sophisticated networking policies tailored to their specific requirements.