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VXLAN overview
Virtual eXtensible LAN (VXLAN) is a MAC-in-UDP technology that provides Layer 2 connectivity
between distant network sites across an IP network. VXLAN is typically used in data centers for
multitenant services.
VXLAN provides the following benefits:
•
Support for more virtual switched domains than VLANs
—Each VXLAN is uniquely
identified by a 24-bit VXLAN ID. The total number of VXLANs can reach 16777216 (2
24
). This
specification makes VXLAN a better choice than 802.1Q VLAN to isolate traffic for VMs.
•
Easy deployment and maintenance
—VXLAN requires deployment only on the edge devices
of the transport network. Devices in the transport network perform typical Layer 3 forwarding.
The device supports only IPv4-based VXLAN. IPv6-based VXLAN is not supported.
VXLAN network model
As shown in
, the transport edge devices assign VMs to different VXLANs, and then forward
traffic between sites for VMs by using VXLAN tunnels.
The transport edge devices are VXLAN tunnel endpoints (VTEP). They can be servers that host VMs
or independent network devices.
An H3C VTEP uses VSIs and VXLAN tunnels to provide VXLAN services.
•
VSI
—A virtual switching instance is a virtual Layer 2 switched domain. Each VSI provides
switching services only for one VXLAN. VSIs learn MAC addresses and forward frames
independently of one another. VMs in different sites have Layer 2 connectivity if they are in the
same VXLAN.
•
VXLAN
tunnel
—Logical point-to-point tunnels between VTEPs over the transport network.
Each VXLAN tunnel can trunk multiple VXLANs.
VTEPs encapsulate VXLAN traffic in the VXLAN, outer UDP, and outer IP headers. The devices in
the transport network forward VXLAN traffic only based on the outer IP header.
