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Bug Reference

CLOUDSTACK-2328

Branch

TBDGithub - vxlan-master branch

Introduction

The purposed plugin will bring the new network isolation methind "VXLAN" to CloudStack.
The plugin is for KVM hypervisor and work with Linux kernel 3.7+ native VXLAN support.

Purpose

This is a functional specification of the VXLAN Network Plugin, which has Jira ID 2328

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Scaling: a maximum of 4094 VLANs per datacenter is possible. This number is however a theoretical maximum. The actual number of VLANs that can be configured is often limited by the capabilities of the physical switches in the data center, as they need to maintain a distinct forwarding table for each VLAN.
Configuration complexity: VLAN information has to be consistently provisioned on all networking hardware
Broadcast containment: broadcasts within one VLAN causes needless flooding on links not using that VLAN
Flexibility: Since VLAN are terminated at layer-2, they do not allow to define virtual networks with span across different L2 broadcast domainsunless VLANs are allowed to transverse the aggregation and core layer of the data center, which can cause traffic "tromboning"domains.

References

draft-mahalingam-dutt-dcops-vxlan-0405
VXLAN documentation in Linux kernel source

Document History

Date

Revision

Author

Description of the change

10/30/2013

0.2

Yoshikazu Nojima

Draft rev. 2

5/17/2013

0.1

Toshiaki Hatano

Initial Draft

Glossary

Term

Definition

VXLAN

Virtual eXtensible Local Area Network

VNI

Virtual Network Identifier

VTEP

VXLAN Tunnel End Point - an entity which originates and/or terminates VXLAN tunnels

CS

CloudStack

Feature Specifications

  • Summary
    The purposed plugin will bring will bring the new network isolation methind "VXLAN" to CloudStack.
    VXLAN is one of emerging technologies to overcome VLAN limitation. VXLAN enable Layer 2 tunneling over UDP/IP with VLAN-like encapsulation and allow 16M isolated networks in the domain.

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  • Performance and Scalability consideration
    TBD.
    VXLAN introduce additonal header, so inner MTU for VMs will be reduced.
    Without configuring (outer/inner) MTU, it will reduce network throughput.

Use cases

There won't be any change to the existing CloudStack workflow.

Architecture and Design description

Software design and architecture:

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  • VXLAN uses IP multicast to handle broadcast inside tunnel, like ARP or DHCP. Figure below illustrate how traffic flows with VXLAN.
    VXLAN doesn't needs tunnel connection setup between VTEP, it just sent packet and learn mapping.

Web Services APIs

None

UI flow

"VXLAN" option will be added to isolation method.
Label "VLAN ID" will be changed to "VLAN ID/VNI"

It may have value to add UI component that allow admin to set parameter like MTU, mapping between VNI and Multicast Group, etc.
But initially, this feature would not have any additonal UI component.

IP Clearance

  • are you expecting to include any code developed outside the Apache CloudStack project?
    • Not at all.

Appendix