Part2: Lecture 03
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Last time(s)?
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• Optical nets! – Spectrum! – Multiplexing! • NSA/NSI! – Lightpaths!Connection provisioning
!
• What do optical networks do?!
–
Provide communication paths between locations
!
• How do they do it? By managing:!
–
Connection
provisioning
and connection
recovery
!
!
Where do you put the
Network models
!
Management plane Control plane Routing plane Data plane Application Network Transport Session Presentation Data Link Physical OSI modelManagement plane
!
The systems, interfaces, and protocols used to manage the network and its services.!
Management plane
Control plane
Routing plane
Control planes
!
The logic and hardware required for the physical transfer of data in the network. !
This intelligence is typically realized in the form of various communication protocols. !
Such protocols can be broadly classified into signaling,
discovery protocols and
routing. !
Management plane
Control plane
Routing plane
Data plane
!
Management plane
Control plane
Routing plane
Data plane The logic and hardware required for the physical transfer of data in the network. !
Layers
!
An optical network consists of layers and partitions.!
!
• Layers!
A control plane will be concerned with the operation at a specific layer. !
In the context of optical networks we are focusing on switching of OXCs
(SONET/SDH) and PXCs (wavelengths).!
Line Path Section Photonic Section Photonic Line Path Section Photonic Section Photonic Line Section Photonic Line Section Photonic
Layering:
!
G.805
!
An ITU-T recommendation that describes the layering concepts, independent from the underlying technology.!
G.805: transport networks
functional models!
link connection link connection
tandem connection link connection network connection subnetwork connection is equivalent to Client layer Server layer Adaptation Termination Client layer Server layer Adaptation Termination link connection network connection trail
Partitions
!
A network can be partitioned (recursively) in smaller parts:
!
•
Topological partitions
!
•
Control domains
!
Control planes can operate:
!
•
Intradomain
, within the same control domain;
!
•
Interdomain
, to build an unified end-to-end control
architecture across control domains.
!
Partitioning:!
information exchange!
How do you transfer information between control domains?!
Control plane interfaces
!
• The User-Network Interface
(UNI)!
This is the control interface
between a node in the client network and a node in the optical network.!
!
• The Interior
Network-Network Interface (I-NNI)!
This is the control interface
between two subnetworks (or nodes) within the same control domain.!
• The Exterior Network-Network (E-NNI)!
This is the control interface
between two nodes in different control domains. !
Control plane abstraction
!
Control functionality can be distinct from the transport functionality, I.e is not implemented in the devices.!
Control plane functions
!
Neighbor discovery!
"a function whereby a network element automatically determines the details of its connectivity to all its data plane neighbors. Neighbor discovery applies to both the UNI and the NNI.!
!
Routing!
"Consists of two aspects: automatic topology and resource discovery. !
!
Signaling !
"the syntax and the semantics of communication between control agents in establishing and maintaining connections.!
Local resource management!
"The representation and accounting of locally available resources controlled by a control agent.!
DCN
!
DCN - the Data Communication Network - is the infrastructure used for messaging between control plane agents in the network.!
It is also used to provide connectivity between control plane agents.!
!
Communication is packet oriented, most often based on IP (v4 or v6).!
!
It can be:!
in-fiber - if the network is associated with the optical data plane!
out-of-fiber - if the network is based on a separate network technology (I.e. a separate IP network)!
Networks work
!
Ossification of the Internet
!
Many aspects of networking are ‘set in stone’.!
New protocols are difficult to implement.!
Most changes are incremental updates.!
There is no service tailored to application needs.!
!
Research community started in 2005 to think about it:!
1. T. Anderson, L. Peterson, S. Shenker, J. Turner, Overcoming the Internet impasse through virtualization, Computer 38 (4) (2005) 34– 41.!
2. J. Turner, D. Taylor, Diversifying the internet, in: Proceedings of the IEEE Global Telecommunications Conference (GLOBECOM’05), vol. 2, 2005.!
Network virtualization
!
A virtual network (VN) is a collection of virtual nodes and virtual links. Essentially, a virtual network is a subset of the underlying physical network resources.!
! ! ! ! ! !
A network environment supporting virtualization allows the coexistence of multiple virtual networks on the same physical substrate.!
Virtualization in the network
!
• Decoupling the services provided by a network from the physical infrastructure!
• Virtual network is a “container” of network services, provisioned by software!
• Faithful reproduction of services provided by a physical network!
– Analogy to a VM – complete reproduction of physical machine (CPU, memory, I/O, etc.)!
Slide courtesy of :!
Slide courtesy of :!
Why?
!
• Sharing the network!
– Different controllers for different users/traffic!
– Isolation (bandwidth, table space, flow space)!
• Abstracting the topology! – One big virtual switch!
– Many virtual switches to one physical switch!
– Arbitrary network topologies!
• While presenting a familiar abstraction! – A network!
Slide courtesy of :!
Network sharing
!
Virtualized Network Backbone!
Virtualized data center/services!
Why sharing the network?
!
• Multiple administrative groups! – Different departments on a campus!
• Multiple customers!
– Tenants in a shared data center!
– Researchers on a shared infrastructure!
• Experiments vs. operational network!
– Support research without breaking real services!
• Expanding a network’s footprint!
– Lease components in another carrier’s network!
Challanges
!
The network security issues for a shared infrastructure:!
!
1. Access control!
– Legitimate users need to authenticated and authorized to access the portion of the network/resources they have been assigned;!
!
2. Path isolation!
– Mapping of users and resources has to be done effectively to avoid interference!
3. Services!
Why Abstract the Topology?
!
• Partial deployment!
– Tunnel through components you don’t control!
• Simplicity!
– Hide inessential details, churn, migration, …!
• Privacy!
– Hide internal details of the network!
• Scalability!
– Present a smaller topology and fewer events!
• Experimentation!
– Try topologies that don’t really exist!
Benefits
!
• Rapid innovation: network services now delivered at software !
Speeds!
!
• New forms of network control: API to NV controller allows creation and management of virtual networks under software control !
• Snapshot, rollback etc. !
• Vendor choice: decoupled networking services from underlying hardware !
• Simplified programming: expose abstractions that make sense to programmers !
• Simplified operations: network state managed like a VM – provision centrally in SW, snapshot, rollback, etc.!
Types of VNE
!
Four main types of VNEs:!
- VLANs – Virtual Local Area Networks! - VPNs – Virtual Private Networks!
- Overlay Networks!
VLANs
"
"!
They create a single broadcast domain that groups hosts with a common ‘interest’.!
!
Pros:!
Configured via software they are easy to manage! Provide isolation and are cost effective.!
802.1Q VLAN frame format
!
type
2-byte Tag Protocol Identifier (value: 81-00)
Tag Control Information (12 bit VLAN ID field, 3 bit priority field like IP TOS)
Recomputed CRC
802.1 frame
802.1Q frame
dest.
address address source data (payload) CRC
preamble
dest.
address address source
preamble data (payload) CRC
Basic VPN component
!
Customer edges (CEs) are connected to one or more provider edges (PEs).!
!
A service provider (SP) manages and provisions the VPN:!
PPVPN - Provider Provisioned VPN.!
!
!
VPNs can operate at different layers:! • Layer1 VPNs!
• Layer2 VPNs! • Layer3 VPNs!
• Higher level VPNs!
Know more:
Provider Provisioned VPNs terminology
Overlay networks
!
• An overlay network is a virtual network that creates a virtual topology on top of the physical topology of another network. !
• Nodes in an overlay network are connected through virtual links which correspond to paths in the underlying network. Overlays are typically implemented in the application layer.!
Overlay Network
!
• Nodes are connected by logical/virtual links!
• Logical Network Layer implemented on top of the physical network!
• Uses different addresses for routing messages!
Architecture
!
•
Unstructured p2p
!
No structure for the
overlay network.
!
!
•
Structured p2p
!
Specific topology that
is ‘easy’ search
DHTs and p2p
!
Distributed Hash Table is distributed over the nodes in the P2P network in order to locate content.!
!
The DHT stores the location (IP address of peer in charge) of the content across the network.!
No need for an indexer or central server.!
! Notable DHTs:! • Chord! • Pastry! • Tapestry! • Kademlia!
DHT identifiers
!
In Chord there is an m -bit identifier. Related to an identifier
circle.!
!
Given m:!
• Assign integer identifier to each peer in range [0,2m-1]!
• Require each key to be an integer in same range!
!
To get integer key, hash original key! – e.g., key = hash(“Led Zeppelin IV”)!
m=2!
0!
1!
2!
Assigning keys to peers
!
• Assign integer to each peer!
• Convert each key to an integer !
• Put (key,value) pair in the peer that is closest to the key!
• Given key k the key will be stored at successor(k)!
Closest is the immediate successor of the key (equal or follows).! First node clockwise from k.!
!
• e.g.,m=4; peers: 1,3,4,5,8,10,12,14; ! – key = 13, then successor peer = 14!
– key = 15, then successor peer = 1!
0001
0011
0100
0101
1000
1010
1100
1111
Who’s responsible for key 1110 ?I am
O(N) messages! on average to resolve! query, when there!are N peers! 1110 1110 1110 1110 1110 1110
Query
!
Query with shortcuts
!
• each peer keeps track of IP addresses of predecessor, successor, short cuts.!
• reduced from 6 to 2 messages.!
1
3
4
5
8
10
12
15
Who’s responsible for key 1110?Content delivery networks
Virtual Extensible LAN.
!
!
• High scalability:!
– From 4096 VLAN ID (12 bits) to 16Millions VNID (VXLAN Network Identifier).!
• Better utilization of network paths relying on L3 routing.!
Interesting that this is supported by software switches too (Open vSwitch)!
!
VTEPs
!
VXLAN is a Layer 2 overlay scheme over a Layer 3 network.!
It uses VXLAN tunnel endpoint (VTEP) devices to map tenants' end devices to VXLAN segments and to perform VXLAN encapsulation and de-encapsulation.!
!
VXLAN packet format
!
Network Virtualization History
!
• Dedicated overlays for incremental deployment! – Mbone (multicast) and 6bone (IPv6)!
• Overlays for improving the network! – Resilient Overlay Networks (RON)!
• Shared experimental testbeds! – PlanetLab, Emulab, Orbit, …!
• Virtualizing the network infrastructure!
– Overcoming Internet impasse through virtualization!
GENI
!
Three main components:!
!
• GENI racks: virtualized computation and storage resources.!
• Software-defined networks (SDNs): virtualized,
programmable network resources.!
• WiMAX: virtualized cellular wireless communication (at selected campuses).!
Programmable networks
!
• A. T. Campbell, H. G. De Meer, M. E. Kounavis, K. Miki, J. B. Vicente, and D. Villela, “A survey of programmable networks,” SIGCOMM Comput. Commun. Rev., vol. 29, no. 2, p. 7, Apr. 1999.!
Programmability and
virtualization
!
• Are programmable networks VNEs?!
!
Maybe not directly, but programmability can ensure the coexistence of multiple networks.!
!
The key is to separate the control plane from the data plane:! Control plane à control software!
Active networks (I)
!
Allows packets flowing through the network to modify the network behaviour.!
Software Defined Networking
!
A short intro based on the course of prof. Jennifer
Rexford !
http://www.cs.princeton.edu/courses/archive/fall13/
cos597E/syllabus.html!
!
SDN and Network
SDN and network
virtualization
!
• Network virtualization != SDN! – Predates SDN! – Doesn’t require SDN! !• Easier to virtualize an SDN switch!
– Run separate controller per virtual network!
– Partition the space of all flows!
Software Defined Networks
!
63
control plane: distributed algorithms
!
decouple control and data planes
Software Defined Networks
!
decouple control and data planes
!
by providing open standard API
!
Software Defined Networks
!
Simple, Open Data-Plane API
"
• Prioritized list of rules!
– Pattern: match packet header bits!
– Actions: drop, forward, modify, send to controller !
– Priority: disambiguate overlapping patterns!
– Counters: #bytes and #packets!
1.
src=1.2.*.*, dest=3.4.5.*
à
drop
2.
src = *.*.*.*, dest=3.4.*.*
à
forward(2)
(Logically) Centralized Controller!
67
Protocols
è
Applications
!
Controller Platform
68
Seamless Mobility
!
•
See host sending traffic at new location
!
Server Load Balancing
"
• Pre-install load-balancing policy! • Split traffic based on source IP!
src=0*, ! dst=1.2.3.4! src=1*, ! dst=1.2.3.4! 10.0.0.1 10.0.0.2
Example SDN Applications
!
• Seamless mobility and migration! • Server load balancing!
• Dynamic access control!
• Using multiple wireless access points! • Energy-efficient networking!
• Adaptive traffic monitoring!
• Denial-of-Service attack detection! • Network virtualization!
Entire backbone
runs on SDN
A Major Trend in Networking
!
Bought for
$1.2 x 10
9
Home reading
!
For the test on May 09 read:!
Literature
!
Chapter 27 – Network and Information Infrastructure Virtualization!
Chapter 5 – Modern Optical Control Planes!
Towards a diversified internet ! by Turner et al.!
!
!
A survey of network virtualization by Chowdhuri et al.!
