jukka lehtniemi 25 march, 2008 supervisor: professor jörg ott instructors: licphil stefan wiklund
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Protection concerns using Switched Ethernet as internal bus for a Telecommunication Network Element. Jukka Lehtniemi 25 March, 2008 Supervisor: Professor Jörg Ott Instructors: LicPhil Stefan Wiklund MSc Juha Eloranta. Outline. Introduction Telecommunication Computer and AdvancedTCA - PowerPoint PPT PresentationTRANSCRIPT
Slide titleIn CAPITALS
50 pt
Slide subtitle 32 pt
Protection concerns using Switched Ethernet as internal bus for a Telecommunication Network
ElementJukka Lehtniemi
25 March, 2008
Supervisor: Professor Jörg Ott
Instructors: LicPhil Stefan Wiklund
MSc Juha Eloranta
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Text 24 pt
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-252
Outline
Introduction Telecommunication Computer and AdvancedTCA Evolution of Ethernet Technology Spanning Tree Protocol Other Link Protection Technologies Network Element Topology Considerations Link Protection Solutions for Network Element Conclusions
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-253
Introduction
Is a switched Ethernet based internal bus good enough solution in terms of link protection in a telecommunication network element?
Different link protection mechanisms available and the suitability for use as a telecommunication element internal bus
The network node architecture is assumed according to the AdvancedTCA specification
Literature study & comparison
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-254
Telecommunication Computer Multiprocessor computing
cluster Variety of different
processors: general purpose processors, network processors, DSPs etc.
Variety of different network interfaces: TDM, ATM, Ethernet
Redundancy Modular board & subrack
architecture in a server cabinet
Resources connected together by internal (switched) bus
Boards
InterSubrackLink
Subrack
Backplane
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-255
Advanced Telecommunication Computing Architecture Open hardware framework Specified by PCI Industrial Computer Manufacturers Group - a
consortium of over 450 hardware manufacturers Designed for reliability concerned applications Mechanical design, platform management, data transport etc. Flexible and loose specifications: profiled further by SCOPE
Alliance AdvancedTCA specifies two subrack level interconnection busses:
base interface and fabric interface. Ethernet is the selected technology for the base interface. It is
generally also seen as the most promising candidate for the fabric interface
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-256
Ethernet Evolution: Shared Bus
Base-2Base-T
Repeater 1
Collision Domain
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-257
Base-T
Switch 1 Switch 2
Ethernet Evolution: Switched Bus
Collision Domains
Full Duplex – CSMA/CD disabled
Base-T
Switch 1 Switch 2
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-258
Ethernet Evolution
The Ethernet technology has evolved from a simple media sharing LAN solution to a versatile and diverse family of frame based computer networking technologies.
From the user protocol perspective it still provides a transparent and compatible frame transmission service
Key enhancements– Switching– Microsegmentation – Full Duplex– Flow Control– Virtual LANs – Connectivity Fault Management
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-259
B3
B1
B6
B2
B5
B4
RootBridge
RP
RP
RP
RPRP
DP DP
DPDPDP
DP BP
DP
BP
DP
BP
DPBP
DP
BP
Spanning Tree Protocol Topology loops in a switched
Ethernet LAN will cause frame multiplication and thus they are unacceptable
The Spanning Tree Protocol (STP) operated by the switches will eliminate such loops by blocking redundant links in the physical topology and restricting the active topology to a simply and fully connected tree
STP provides topology recovery in the case of link failure. This can be used as a link protection solution
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2510
Spanning Tree Protocol
STP propagates the topology information by continuous transmission of distance vectors
New protocol version called Rapid STP (RSTP) has been standardized
Proposal-agreement based communication of RSTP responds faster to topology changes
Multiple STP (MSTP) protocol defines per VLAN spanning trees
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2511
Link Aggregation
Link Aggregation is defined by IEEE 802.3 Allows bundling multiple physical links to a single logical link Bandwidth extension Redundancy
Switch 1 Switch 2
Link Aggregate
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2512
Resilient Packet Ring
RPR is specified by IEEE 802.17
Dual Ring topology Service priorities and fairness Topology discovery and
continuity check Healing strategies: Steering
and Wrapping 50 ms protection time against
link failure
SpanFailure
Update!
Update!
Update!
Update!
SteeringWrapping
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2513
Ethernet Protection Switching
ITU-T Rec. G.8031 / Y.1342 Linear Protection Switching VLAN based Point-to-Point connections Failure detection by Ethernet CFM
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2514
Ethernet Automatic Protection Switching By Extreame Networks Switched Ethernet, Ring topology One way transmission: primary port transmitting and
secondary port blocking Continuous health check polling by Master Node Recovery based on filtering database flush ordered by
Master Node and standard Ethernet address learning mechanisms
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2515
AdvancedTCA Subrack
Two switch boards (per interface) Dual Star topology BASE-T specified, BASE-KX or BASE-KR likely in future 8 uplink/interconnect ports per switch board defined by SCOPE
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2516
5 Subrack Topology: Bus & Ladder
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2517
5 Subrack Topology: Star
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2518
5 Subrack Topology: Full Mesh
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2519
5 Subrack Topology: Ring
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2520
Link Protection Solutions forMultisubrack AdvancedTCANetwork Element: Requirements
Primary requirement: < 50 ms protection switching time Manageable complexity Reasonable design, manufacturing and maintainance
costs
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2521
Solutions
Link Aggregation Ethernet Protection Switching Ethernet Automatic Protection Switching Redundant Packet Ring Physically Distinct Switching Planes (Rapid) Spanning Tree
•Point-to-point: Too fine grained (complex) total solution
•Master Node is a single point of failure
•No guaranteed switch over time < 50 ms
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2522
Recommended solutions: RPR
Guaranteed switch over time No need for protection switching
supervision clients on the boards: A board may transmit using either of the subrack bridges at any time
Extendibility: no practical restrictions on the amount of subracks to be connected to the ring interconnect
Equipment prices are presumable higher
Additional LAN technology layer and tunnelling of Ethernet frames on the ring
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2523
Recommended solutions: Physically Distinct Switch Planes Pure Ethernet solution Prices of the equipment probably
lower Topology extension by number of
subracks in case of the redundant star topology may require additional interface boards in central subrack
Supervision and switch-over mechanism needs to be in place on each board
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2524
Conclusions
Variety of link protection solutions for Ethernet exists Most of them do not meet the requirements for a
telecommunication network element Recommended solutions identified by the study:
– RPR interconnect – Construct of redundant, distinct, loopfree switching planes
Further analyzing of these alternatives with proper simulations or real hardware testing is suggested
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Master's Thesis Presentation Jukka Lehtniemi 2008-03-2525