quality of service in ip networks presented by: john [email protected] rick...
TRANSCRIPT
Quality of Service in IP
Networks
Presented by:
John Railsback [email protected]
Rick Blum [email protected]
Sharing the Knowledge Behind the Network
Lucent Worldwide Services Knowledge Seminars
04/20/23 2
Background
Lucent Worldwide Services is a provider of communications consulting, intelligent maintenance, and management solutions for next generation networks
Seminar objectives Present the major factors driving QoS Highlight current QoS technologies
and techniques Provide insight into the future direction
of QoS for IP networks
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QoS Research
Web-based industry survey conducted September 2000
108 respondents
Represent a cross-section of end-user organizations and network solutions providers
Survey report available at www.lucentnps.com/surveys
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QoS Definition
Management of available bandwidth to deliver consistent, predictable data (packets) over an IP-based network in terms of:
Latency - delay that an application can tolerate in delivering a packet of data
Jitter - variation in latency Loss - percentage of lost data Throughput - amount of data carried Availability - network uptime
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The IP Network Problem
Congestion continues to plague the Internet• Traffic expands = or > bandwidth
• ”Best-effort" performance dictated by the very design of the Internet Protocol (IP)
Mission critical applications, e.g., IP Telephony and ERP, require prioritization• Service Level Agreements (SLAs) expected
• Customer expectations increase with bandwidth
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Why QoS
Over-provisioning bandwidth not cost effective in the long run• Users will consume bandwidth as fast as produced
Need reliable data delivery• Mission critical applications
– ERP, SAP, Financial Market data
• High bandwidth, low latency applications– Video and audio streaming, video conferencing,
voice
Provide value-added services with SLAs
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QoS Technologies
Reservation• Allocates resources on a per-flow basis
• Flows include information such as transport protocol, source address & port, destination address and port
– Intserv/RSVP
Prioritization• Traffic flows are aggregated and categorized
by "class of service”– DiffServ and IEEE 802.1p
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Integrated Services
Defined in RFCs 2205, 2206 - www.ietf.org/rfc.html
Implemented by four components• Signaling protocol (RSVP)
– Reserves resources and establishes paths before transmitting data
• Admission control routine– Determines whether a request for resources can be granted
• Classifier– Places packets in specific queues based on classification
result
• Packet scheduler– Schedules the packet to meet its QoS requirements
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RSVP
Signaling protocol that can operate in "native mode" or "encapsulated mode" within a UDP header
Operates in tandem with either a TCP or UDP "flow" to reserve resources among RSVP-enabled routers
Also being used to signal QoS into DiffServ and MPLS networks
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Differentiated Services (DiffServ)
Defined in RFCs 2474, 2475 Creates classes of service for traffic flows
with different priorities
• Aggregates large numbers of individual flows at the edge of the network into small numbers of aggregated flows through the core of the network
• Flows are marked at network edge in the IPv4 ToS field (DS field).
• Services applied through the core
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Building Blocks of DiffServ
Packet Classifiers• Packets sorted into queues based on values in the
DS (DiffServ) field
Traffic Conditioning Policies• Metering, Marking, Shaping and Policing based on
DSCP and packet header data
Forwarding/Per Hop Behaviors• Expedited Forwarding and Assured Forwarding
Policy Managers• apply and communicate QoS policy
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Packet Classifiers
DiffServ Code Point (DSCP)• Maximum of 64 classes of service
• Replaces IP TOS field
• Packets sorted into queues based on DSCP values
Source: QoS Forum
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Traffic Conditioning
Metering• Monitors traffic patterns against traffic profiles
Marking• DS field marks packet with specific values for each
PHB (marked by edge routers) Policing
• Ingress routers drop or remark traffic that does not meet profiles and policies
Shaping• Egress routers control forwarding rate of packets
and controls traffic flow to avoid congestion
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Per Hop Behaviors
Expedited Forwarding• Guaranteed delay and jitter
(similar to ATM CBR)
– Provides a Virtual Leased Line service
– Non-conforming policed on ingress and shaped on egress of Diffserv domain
– Manual provisioning or signaling protocols required for quantitative guarantees.
– Typically implemented with strict priority queuing
Assured Forwarding (AF)• Similar to ATM nr-VBR QoS• Four AF classes with three
codepoints each• AF classes not specifically
defined regarding performance
or priority between classes– Non-conforming traffic marked
at the edge– RED queuing most often used.
• Better then Best Effort Delivery– Gold, Silver, Bronze services
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DiffServ Code Points for Expedited Forwarding and Assured Forwarding
AssuredForwarding
Class 1 Class 2 Class 3 Class 4 Class 5
Low DropPrecedence
001010 (AF11) 010010 (AF21) 011010 (AF31) 100010 (AF41)
Medium DropPrecedence
001100 (AF12) 010100 (AF22) 011100 (AF32) 100100 (AF42)
High DropPrecedence
001110 (AF13) 010110 (AF23) 011110 (AF33) 100110 (AF43)
ExpeditedForwarding
101110
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IEEE 802.1p
Traffic-handling mechanism for supporting QoS in LANs
Allows a classification/prioritization of differentiated services analogous to DiffServ
Operates at layer 2 (MAC) layer on a switched Ethernet network• Defines a field in the layer-2 header of “802”
packets that can carry one of eight priority values
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IEEE 802.1p
Scope of 802.1p priority mark is limited to the LAN. Once packets are carried off the LAN, through a layer-3 device, the 802.1p priority is removed.
802.1p often defined with 802.1q• Together, define various VLAN (virtual LAN)
fields, as well as a priority field Implemented in hardware (switches and
routers)
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Multi Protocol Label Switching (MPLS)
More scalable mechanism for IP over ATM than classical overlay model • Edge routers can peer with nearby MPLS nodes
• Avoids N2 scaling issues with ATM meshed networks
Traffic Engineering - using explicit routes and constraint-based routing for better load balancing.
As a tunneling mechanism to interconnect intra-VPN sites
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MPLS Network
LSPs provide transport for
• MPLS VPNs
• Traffic Engineered Explicit Routes
• DiffServ Aggregates
CloudIGP Domain
LSR
Legend
EdgeLSR
LSR
LSP
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QoS Implementation Issues
Inter-domain and Inter-Service Provider interoperability Vendor interoperability Limiting RSVP implementation in the core Use RSVP to signal QoS to DiffServ and MPLS network
cores QoS support in applications Monitoring and measuring QoS Billing, accounting, pricing Security and authentication Policy management
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For Internet and WANs, DiffServ
and MPLS top candidates for
aggregated traffic flows and QoS
DiffServ from the edge through the core, or
DiffServ at the edge, MPLS at the core
RSVP for signaling
The Bottom Line
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For LANs and enterprise networks, 802.1p is top edge QoS mechanism using RSVP for signaling
Microsoft supports RSVP in Windows 2000
Microsoft APIs for application
based QoS development
The Bottom Line
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Where do you start? Planning
Match QoS Mechanism to Applications, Services, Desired Traffic Types, and SLAs
Determine needed management and accounting platforms for measuring performance and usage
Design Determine required hardware and software
features, policy manager platforms, and policies, perform proof of concept
Implement Deploy QoS mechanisms and associated
services Operate!
The Bottom Line
04/20/23 30
Lucent Worldwide Services Professional Services
Service Provider Solutions• Business consulting• Custom on-premises solutions• Network engineering & design deployment• Network operations & management • Program management
Enterprise Consulting Solutions • Business consulting• Network management consulting• Microsoft technologies consulting• Performance engineering• Security solutions• Voice/Data convergence
04/20/23 32
Thank You
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