Information Technology Reference
In-Depth Information
By counting the total number of packets related to a certain port in all the Flow-
Tables in forwarding node, the driver can learn the link utilities. By sending certain
commands (normally, OpenFlow switches provide those commands) to the OpenFlow
switches, LLDP extension module can also learn the OpenFlow version, number of
FlowTables, and flow entries in each switch. Furthermore, the LLDP extension can
call the OpenFlow switches functions or commands by the SSL (Secure Sockets
Layer) control channel between controller and switches.
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Network View Transfer Format
.
This paper suggests JSON (JavaScript Object Notation) as a basic implementation,
and the XML(eXtensible Markup Language), YANG[2], YAML[16] as alternatives.
Those languages have the ability to enable EWBridge with the following advantages:
(1) They are vendor-independent and application-independent, thus the network view
transfer format is independent with the storage systems; (2) They allow explicit defi-
nition of the inherent structure according to the requirements; such features make the
network view message format flexible and easy to extend; (3) They are files and not a
data packet format. The elements are easy to extend.
•
Virtual Network View for Privacy and Scalability
.
Usually the network view is the entire network information. However, some domains
may be willing to expose only a part of the network view due to their privacy con-
cerns. EWBridge supports abstracting a physical network to a virtual network for such
domains. As showed in Figure 3, routing paths from the ingress port to the egress port
of an abstract network can have SLA-level path attributes such as time latency, relia-
bility, bandwidth, packet loss rate like VP 1, VP 2, VP 3. To abstract a network fur-
ther, EWBridge supports abstracting a network to a virtual node like network 2. The
virtual node for network 2 only retains the three physical inter-network links: link2,
link3, link4.
Fig. 3.
Physical view to virtual view (PP: Physical Path; VP: Virtual Path; OF: OpenFlow; S:
Switch; bd: bandwidth; t: time; bps: bits per second)
