Misunderstanding number one: SDN sure to use OpenFlow protocol to configure forwarding plane
OpenFlow just development of the earliest, the biggest influence southbound interface, but not the only one, there are others, such as OpenDayLight been proposed another southbound interface, including existing and newly defined, such as PCEP, NETCONF, SNMP and the like.
Misunderstanding number two: SDN standardization requires hardware forwarding plane
it's just OpenFlow requirements, SDN is not a requirement, in fact, many manufacturers, did not bother to pursue standardization of hardware forwarding plane, even if it is OpenFlow standard organization of ONF, also consider a compromise.
Misunderstanding number three: SDN devices can replace all the equipment
it is extremely tricky to speak, first, SDN is not suitable for all networks, second, even if a suitable network, SDN is not a substitute for all levels of equipment.
Misunderstanding four: SDN get all vendors to support
many companies apparently very positive, actually just a passive rather than active front row forward. Many companies, especially some large market share equipment manufacturers / chip business, their market share has been great, then toss again, it will not be big. But had to follow frustrating, because if people do not keep up their own market share shrank.
Misunderstanding five: SDN is equipment manufacturers initiated
these years of Internet development, new technologies are basically the vast majority of equipment manufacturers and proposed guidance, including a variety of standard IETF, IEEE, ITU, but different SDN, SDN's the original author and promoter of all users, not the manufacturer of the network equipment network equipment, it is very important to determine the interest-oriented.
Misunderstandings six: SDN is mainly used in the data center network
SDN has been able to rise rapidly, the main driving force comes from the data center, more precisely, from the data center network virtualization, if there is no network virtualization, data center network with other lacks distinction for SDN . With the development of SDN, people found other networks, including operators, enterprise local area network, wireless network, security and so on are applicable.
Misunderstanding seven: SDN controller is centralized control
centralized control have scalability issues, so centralized control controller is only suitable for small and medium sized networks, for large networks, distributed control required, namely multiple controller work together, each a controller responsible for part of the network, but also to coordinate with each other before, which may have hybrid control, local focus, global distribution.
Misunderstanding eight: SDN SDN chip devices require special support
on the market is not exclusively for OpenFlow / SDN ASCI's commercial chips, SDN stressed classification forwarding plane and control plane, standardized interface, but it does not mean you must use a special chip, only However, if the chips can be customized for SDN innovation needs, better support for SDN. Even if no specific SDN chip, equipment manufacturers can be configured to traditional packaged chip, provides SDN part in line with the needs of the southbound interface up.
Misunderstanding nine: SDN devices are relying on static configuration
SDN application device is configured by controller, these programs reflect the will of the administrator, but can be run automatically, not necessarily static configuration, for example, still allows routing protocol running on the controller, the calculated result is sent to the switch via the controller.
Misunderstanding ten: SDN is only available in Switch
SDN lot to talk about when talking about the main switch, after all, is closely related to the SDN OpenFlow standard is designed for the switch, but also originated in SDN OpenFlow switch, but in fact, the core concept of SDN is the forwarding plane and control plane separation, software-defined network is not limited to the switch, that is to say SDN concept can have it all routers, firewalls, and other products can be used to build wireless network equipment.
SDN should not be forgotten martyrs
Casado, Mckeown, who is actually not the first to propose the separation of the control plane with the forward face of people, as early as 2004, Intel, University of North Texas, Nokia's researchers put forward with a RFC 3746 forwarding and control element separation ( ForCES) framework, but this informational RFC has been in a state (represented public and inform, not considered formally widely recognized Internet community standards).
In this RFC, and they first proposed the control plane and forwarding plane separation concept, as well as a network framework, in the framework of which has now SDN prototype, but this RFC does not define the specific implementation criteria.
By 2010, Zhejiang Industrial and Commercial University, Luleå University of Technology, IBM, Intel, Nokia, Znyx scientific and technical staff also proposed a new RFC 5810 forwarding and control element separation ( ForCES) protocol specification. In this new RFC, and they have achieved a similar OpenFlow protocol standards, now this has become standard track RFC status (said that it has been recognized as the official standard), said to be related to Zhejiang University of Technology researchers as early as 2003 it has been studied before and after the start in this area.
