Building an Infrastructure for Cloud

Randy Bias of CloudScaling has published an insightful white paper on how to build a scalable infrastructure for IaaS cloud.

In this white paper, Randy illustrated an emerging technique,  “L2oL3”.

An emerging technique that offers far more promise is that of network virtualization. Network virtualization is a combination of technology and methodology that allows for the use of L3 network designs for the service provider, but L2 network designs for the consumer of the cloud. This approach is sometimes referred to as “L2 over L3” or “L2oL3”. The advantage of this is that it uses well understood network designs for both the provider and consumer.

The key points in Randy’s white paper are,

  1. L3 (IP) is proven to be scalable. Internet is built on IP. There are many protocols, such as ECMP/OSPF, that can be used in a data center.
  2. L2 (Ethernet) is the desired network layer for virtual machines, but Ethernet is not scalable.
  3. The ideal data center network is to build a scalable network with L3 (IP) scheme. On top of the L3 network, build a virtualized L2, with techniques such as GRE tunneling,  to facilitate the flexibility required by the virtual machines.
  4. To enable this virtualized L2, Openflow technology is a good fit. With Openflow dynamically assigning and managing the L2 entries on the virtual network, users can not only create L2 on demand, but also migrate VM to different location without disrupting the network topology.

The direction Randy points out is quite consistent to what we see at Pronto.

  1. In order to build this kind of scalability, data centers will need powerful while low-cost ToR switches (such as Pronto 3290 and Proto 3780) to build a distributed L3 network. These ToR need to support scalable L3 protocols, such as ECMP/OSPF.
  2. These ToR need to support Openflow protocol.
  3. Data center will need to have Openflow controller to dynamically manage the virtual L2 on top of the physical L3 topology. Pronto is now working with some partners to provide this solution.

About James Liao
James is a data center architect, focusing on the scalability and operation of data center infrastructure.

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