VXLAN: Is it good or bad?

At the recent VMworld conference, the VXLAN virtual extensible LAN statement proposed by Cisco and VMware aroused great repercussions among network engineers. Is it a useless virtual environment method, or does it make sense? In fact, it is in the middle of the two.

What is VXLAN?

It is a simple mechanism for encapsulating MAC in UDP. It can create a virtual layer-2 subnet that spans multiple physical IP subnets.

Why do we need this new technology?

Currently, more than one standard can encapsulate MAC, including EtherIP and GRE channel bridging, in IP addresses. However, neither of them can perform VLAN logic marking. Therefore, you can only use up to 4,096 different VLANs. Even if these criteria can be used to separate the logical network, you must analyze the MAC header information in depth to find the virtual part ID. VXLAN uses a 24-bit shard ID to deploy millions of virtual networks in a data center.

Moreover, the VXLAN data packet format is easily implemented in hardware, so it may be more tightly integrated with physical network devices in the future.

Is VXLAN another patented technology?

No. It is an IETF draft jointly proposed by VMware, Cisco, Arista, Broadcom, Citrix, and RedHat. It is difficult for a team that is better than this, the addition of Arista and Broadcom is because Broadcom is producing the chips used by the Arista data center switch ).

When do I need VXLAN?

Someone declared: "If there are more than 250 virtual machines in the data center, you should consider using VXLAN ." Many people think that) VXLAN should be used only when a large number of Logical Networks are required. If there are only a few logical networks, we should still use time-tested technologies, such as VLAN.

Disadvantages of VXLAN standards

What is the difference between VLAN and VXLAN?

VXLAN is obviously more scalable with 4,096 VLAN networks and 16 million VXLAN networks), but it still faces a huge problem: although some data center switch vendors are expected to support layer-3 VXLAN terminals, logical subnets encapsulated with VXLAN cannot communicate with physical devices, such as switches, load balancers, or firewalls.

The only way to connect a VXLAN to an external device is to use a Virtual Layer-3 network device, such as a vShield Edge, Vyatta router, or F5 Load balancer-A vNIC is required in a physical VLAN, one or more VXLAN instances are required.

Can I run VXLAN in any IP network?

Similar-but the IP multi-channel broadcast is used to implement layer-2 flood broadcast or multi-channel broadcast ).

Can I use VXLAN for remote VM movement?

The premise is that you can support IP multicast between data centers. VXLAN cannot handle long-distance traffic latency, but this must be done when virtual machines are transmitted between multiple data centers in the same logical subnet.

So what are the selling points of VXLAN?

If you want to create a fully virtualized infrastructure cloud service and want to connect the customer subnet and external network through the Virtual device configured by the customer, VXLAN is an ideal technology.

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