Shulou(Shulou.com)06/01 Report--

Recently, I have been watching overlay to record the learning process, mainly the framework of overlay.

Psychological representation:

Layer 2 Virtualization vxlan

What is overlay?

Overlay is a virtual network relative to undelay. Underlay is a physical network, and overlay uses the logical network and nodes of underlay to form a virtual network. The extension of physical networks to the cloud and virtualization is the key to cloud convergence.

What problem has been solved?

With the popularity of cloud computing, big data and mobile Internet, a large number of virtual machines are needed, often using layer 2 technology, which creates a new demand.

1. Migration is not limited by architecture.

The scale of traditional protocol stp network should not be too large. The extension protocol needs the support of software and hardware, and the deployment cost is increased.

Overlay is encapsulated on ip and distributed over the network using routing. There are no special requirements for equipment. The existing network can be used for low-cost transformation.

two。 A network large enough.

If there are many second-tier devices, the second-tier items will be large, which is a challenge for the second-tier items.

After the overlay is blocked, the network only appears as the endpoint address of the tunnel, and the second-layer table items are scattered on the vtep.

3. Enough network isolation capabilities.

There are only 4000 vlan, and 4000 is not enough for cloud services.

Overlay has either 24bit or 64bit and supports at least 16000000 logical networks.

The technology used?

TRILL (Transparent Interconnection of Lots of Links) of telecom equipment manufacturers

FabricPath of Cisco

SPB of IEEE

Disadvantages: because it is a new protocol, it needs the support of new equipment.

VXLAN, NVGRE, STT of IT manufacturer

The schemes are similar, they are all mac in ip/udp.

VXLAN and STT have lower requirements for traffic balancing for existing network devices, that is, load link load sharing has good adaptability. General network devices can perform link aggregation or equivalent routing traffic balancing for L2-L4 data content parameters, while NVGRE requires network devices to be aware of GRE extension headers and HASH flow ID, and hardware upgrades are required. STT has made great changes to TCP, the tunnel mode is close to UDP, and the tunnel construction technology is innovative and complex, while VXLAN makes use of the existing general UDP transmission with high maturity.

On the whole, VLXAN technology has relative advantages.

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