Vxlan and MPLS: from data center to Metro Ethernet

In recent years, Cloud Computing 、 virtualization 、 The evolution of container technology promotes the application of network virtualization technology .MPLS and VXLAN Both have applied the concept of virtualization , To express the logical network architecture , For more complex and flexible domain management , But they meet different needs . This article will compare VXLAN And MPLS The difference between , And explain why VXLAN In metropolitan area network and wide area network MPLS More popular .

VXLAN still MPLS？

First, let's quickly review VXLAN and MPLS What are the differences ？

Multiprotocol label switching （MPLS） It is a high-speed method of using tags to guide data on an open communication network 、 Efficient transmission technology . Multi agreement means MPLS It can not only support a variety of network layer protocols , It can also be compatible with a variety of data link layer technologies of layer 2 . This technology is specially used to simplify the data transmission between two nodes , Replace long network address with short path label .

MPLS Add more sites without a lot of configuration .MPLS Also with the IP irrelevant , It just simplifies these IP The implementation of the .MPLS over VPN Added an extra layer of security , because MPLS No built-in security features .

Virtual scalable lan (VXLAN) Will be the first 2 Layer Ethernet frames are encapsulated in the 3 layer UDP In the packet , So devices and applications can communicate over large physical networks , It's like they're on the same Ethernet 2 Layer network .VXLAN Technology takes the existing three-tier network as Underlay The Internet , Build a virtual network on its second layer , namely Overlay The Internet .

And MPLS comparison ,VXLAN Is a relatively new technology . As a network virtualization technology ,VXLAN Solves scalability issues related to large-scale cloud computing setup and deployment .

Why? VXLAN Compare... In the data center network MPLS More popular ？ Three points can be summed up ：

• Support MPLS Routers of tend to support VXLAN The cost of layer 3 switches in the data center is higher .
• be based on MPLS Of VPN Resolver The solution requires close coupling between edge devices and core devices , Therefore, every node in the data center network must support MPLS.
• Master MPLS There are few data center network engineers with professional knowledge .

MPLS Router cost

For a long time , Some service providers have been interested in the idea of using data center level switches to build low-cost metropolitan area networks .20 Many years ago , The first generation of competitive Metro Ethernet service providers （ Such as Yipes and Telseon）, It built its own network with the most advanced Gigabit Ethernet switch in the enterprise network at that time . However, such networks are difficult to provide large-scale SP Required scalability and resiliency , Pictured 1 Shown .

  chart 1： Traditional layer 2 network

therefore , Most large SP All turned MPLS（ As shown in the figure below ）. However ,MPLS Routers are more expensive than ordinary Ethernet switches , And the problem of cost difference has not been effectively solved in the following decades .

chart 2：IP/MPLS The Internet

Today's data center level switches and VXLAN Overlay Combination of Architecture , It can eliminate pure to a great extent L2 The disadvantages of the Internet , No need MPLS The high cost of routing , This has led to a new round SP Focus on  .

Close coupling between core and edge

be based on MPLS Of VPN The solution requires close coupling between edge devices and core devices , Therefore, every node in the data center network must support MPLS. by comparison ,VXLAN Only edge nodes are required （ for example leaf Switch ） Medium VTEP, And you can use any support IP Or IP Transmission network to realize data center Spine And data center interconnection (DCI).

MPLS Professional knowledge

Outside of large service providers ,MPLS Technical learning is difficult , Relatively few network engineers can easily build and operate based on MPLS Network of . and VXLAN Relatively simple , It is becoming a basic technology widely mastered by data center network engineers .

The progress of data center switching technology makes it based on VXLAN Metropolitan area network and wide area network become possible

Today's data center switching chips , For example, Broadcom Trident 3 and Trident 4, Many functions are integrated , To base on VXLAN Metropolitan area network (man) is possible . Here are two key examples ：

• Hardware based VTEP Support line speed VXLAN encapsulation
• Extended tables provide creation flexibility 、 Scalable second 3 layer Underlay Networking and multi tenancy Overlay The size of routing and forwarding required by the service .

in addition , Newer data center level switches have powerful CPU, It can support advanced control planes that are essential for extending Ethernet services , Whether it's BGP EVPN（ A protocol based approach ） Or based on SDN Protocol free control plane .

therefore , In many metropolitan area network applications , No more specialized （ High cost ） Routing hardware .

For man and WAN VXLAN Overlay framework

Overlay Network has been widely used in various applications , Such as data center network and enterprise SD-WAN. these Overlay A key thing that networks have in common is that they are related to Underlay The network is loosely coupled . In principle, , As long as the network provides enough capacity and elasticity ,Underlay The network can be constructed by any network technology and use any control plane .Overlay Define only at the service endpoint , stay Underlay There is no service provision in the network node .

SD-WAN One of its main advantages is that it can use a variety of networks , Including broadband or wireless Internet services , These services are widely available and cost-effective , And provide enough performance for many users and applications . When VXLAN Overlay When applied to man and WAN , It will bring similar benefits , Pictured 3 Shown .

chart 3：VXLAN Overlay framework

Building man to provide Ethernet private line (E-Line)、 Multipoint Ethernet LAN (E-LAN) Or the first 3 layer VPN (L3VPN) When waiting for business , Care must be taken to ensure that Underlay Can meet the needs of such services SLA.

be based on VXLAN Metropolitan area network of Overlay Control plane options

up to now , Our main concern is VXLAN be relative to MPLS Advantages in network architecture and capital cost , That is, the advantages of the data plane . however VXLAN There is no specified control plane , So we need to take a look Overlay Control plane options .

Used to create VXLAN Overlay And to provide Overlay The most famous control plane option for the service should be BGP EVPN, It is a protocol based approach , The service must be configured in each edge node .BGP EVPN The biggest drawback of is the complexity of the operation .

Another non protocol approach is to use SDN and SDN Services defined in the controller , Then the data plane of each edge node is programmed . This eliminates protocol based BGP EVPN Most of the operational complexity of . However , Centralized SDN Controller architecture （ The data center architecture within a single site is acceptable ） When applied to man and WAN , It will bring serious scalability and elasticity challenges . therefore , For man , It is not certain whether it is better than MPLS Better choice .

There is a third option —— Decentralized or distributed SDN, among SDN The controller functions are fully replicated and distributed throughout the network . This can also be called “ No controller ”SDN, Because it does not require a separate controller server / equipment , It completely eliminates centralized SDN Scalability and elasticity of control , While preserving the benefits of simplifying and accelerating service configuration .

surface 1： Compare the metro network MPLS and VXLAN Options

Deployment options

because VXLAN Allows you to Overlay Service delivery and Underlay Network decoupling , So it creates MPLS Unable to match deployment options for , For example, in the existing IP Virtual services at the bottom Overlay, Pictured 4 Shown . be based on VXLAN The switches are deployed at the edge of the existing network , And expand it according to business requirements , New Ethernet and can be added without changing the existing network VPN Business , Add new revenue .

chart 4： On the existing metropolitan area network VXLAN Overlay deployment

chart 5 The metropolitan area network infrastructure shown in the figure can support MPLS All the services that the network can provide , Including commercial Internet 、 Ethernet and VPN Service and consumer triple service , At the same time, it completely eliminates MPLS The cost and complexity of .

chart 5： have VXLAN service Overlay Integrated metropolitan core

* Department of literature SDNLAB Compile and compile pluribusnetworks Official website

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