Network Support for QoS – DiffServ and IntServ Hongli Luo CEIT, IPFW.
1 Network Architecture and Design Internet QoS Differentiated Services (DiffServ) Multiprotocol...
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Transcript of 1 Network Architecture and Design Internet QoS Differentiated Services (DiffServ) Multiprotocol...
Network Architecture and Design 1
Internet QoS
Differentiated Services (DiffServ) Multiprotocol Label Switching (MPLS)
Reference
Zheng Wang, Internet QoS, Architectures and Mechanisms for QoS, ISBN 1-55860-608-4, 2001.
Network Architecture and Design 2
DiffServ - Overview
Integrated services provides QoS; but Problem of scalability
The routers have to maintain state on every flow passing through them.
Heterogeneous networks may not be able to provide particular QoS controls or even RSVP.
Differentiated service (DiffServ) aims to offer QoS to aggregated flows.
Network Architecture and Design 3
DiffServ - Overview DiffServ defines Differentiated Service Code
Point (DSCP) in IPv4 TOS field, IPv6 Traffic Class field.
All traffic in one DSCP is treated the same. Per hop behaviour (PHB) is determined by
DSCP of packet. Service Level Agreements concern aggregate
traffic not individual flows.
Network Architecture and Design 4
DiffServ - Operation
classifier marker
meter
Shaper/dropper
To interiornodesInput
Network Architecture and Design 5
DiffServ - Traffic conditioning Classifier
Marks packets according to classification rules. Meter
Checks whether the traffic falls within the negotiated profile.
Marker Marks traffic that falls within profile.
Shapper/DropperDelays and then forwards, discards, or remarks traffic.
Network Architecture and Design 6
DiffServ - Operation
2-Bit Differentiated Services Architecture for the Internet Premium service
Premium service levels are specified as a desired peak bit rate for a specific flow
Assured service Best-effort service
Network Architecture and Design 7
DiffServ - Operation Like leaky bucket with 2-bit designators (not just CLP setting). By
software not built into hardware. In-profile traffic is marked:
A-bit is set in every packet Out-of-profile (excess) traffic is unmarked
A-bit is cleared (if it was previously set) in every packet; this traffic treated as best-effort
r bps
b bits
metering in-profile traffic
out-of-profile traffic
user profile (token bucket)
set A-bit
clear A-bit
assured traffic
Network Architecture and Design 8
DiffServ - Operation In-profile traffic marked:
Set P-bit in each packet Out-of-profile traffic is delayed, and when buffer overflows it is dropped
r bps
b bits
Metering/Shaper/Set P-bit
in-profile traffic
out-of-profile traffic(delayed and dropped)
premium traffic
user profile(token bucket)
Network Architecture and Design 9
Problems of DiffServ Does not support dynamic reservations only
static. Scalable, but provides weaker services than
IntServ (due to aggregation). It is not yet clear what kind of guarantees can be
given to end-to-end services (how to translate user-QoS to net-QoS?).
Missing of standardized resource management in every node. Solution: Bandwidth Broker (BB)
Network Architecture and Design 10
Bandwidth Broker (BB) The BB performs three distinct tasks:
Negotiation of SLAs with BBs of neighbouring domains Translation of SLAs into one or several Traffic Control Agreements (TCAs)
for edge devices Delivery of the TCAs to the edge routers of the administered domain
Network Architecture and Design 11
IntServ Vs DiffServ
Integrated Services
Differentiated Services
QoS guarantee Per data stream Aggregated data streams
Configuration Per session end-to end
Between domains
Duration of guarantee
Short-lived Long-term
Signaling RSVP Not yet defined
Network Architecture and Design 12
IntServ Vs DiffServ IntServ provides fine grain control and handles
dynamic allocation of resources to flows DiffServ provides course grain control of flows
through their aggregates The two together can be combined to provide
scalable end to end Integrated service, using a DiffServ region as a single element
Controlled Load can be implemented over Assured Forwarding PHB
Guaranteed can be implemented over Expedited Forwarding PHB
Network Architecture and Design 14
Internet QoS
Differentiated Services (DiffServ) Multiprotocol Label Switching (MPLS)
Network Architecture and Design 15
MPLS Overview
MPLS (Multiprotocol Label Switching) Improves the forwarding speed of a router. Introduces new capabilities for large IP
networks Introduction of many of the qualities and
attributes of switched networks to IP networks Integrates Layers 2 and 3.
Network Architecture and Design 16
MPLS Operation MPLS Components
Edge-LSR: Edge-Label Switching Router Assigns a label in an incoming IP packet
Removes the label of an incoming IP packet
LSP: Label Switching Path The path that a packet follows in an MPLS network
LSR: Label Switching Router Makes forwarding decisions based SOLELY on the contents of
the label (basic advantage)
Strips off the existing label and applies a new label which tells the next hop how to forward the packet
Network Architecture and Design 17
MPLS – Traditional IP Routing
47.1
47.247.3
IP 47.1.1.1
Dest Out
47.1 147.2 2
47.3 3
1
23
Dest Out
47.1 147.2 2
47.3 3
1
2
1
23
IP 47.1.1.1
IP 47.1.1.1IP 47.1.1.1
Dest Out
47.1 147.2 2
47.3 3
Network Architecture and Design 18
MPLS – MPLS RoutingIntfIn
LabelIn
Dest IntfOut
3 0.40 47.1 1
IntfIn
LabelIn
Dest IntfOut
LabelOut
3 0.50 47.1 1 0.40
47.1
47.247.3
1
2
31
2
1
2
3
3
IntfIn
Dest IntfOut
LabelOut
3 47.1 1 0.50
IP 47.1.1.1
IP 47.1.1.1
Network Architecture and Design 19
MPLS Label Format IP packet is encapsulated in MPLS
header and sent down LSP
IP packet is restored at end of LSP by egress router TTL is adjusted also
…IP Packet
32-bitMPLS Header
Network Architecture and Design 20
MPLS Label format
TTLLabel CoS S
Label Class of service Stacking bit Time to live
Decrement at each LSR, or Pass through unchanged
Network Architecture and Design 21
MPLS Fast forwarding speed Traffic Engineering
constraint-based routing explicit routing ability to compute a path at the source ability to reserve network resources and to modify link
attributes Voice/Video on IP
delay variation + QoS constraints Virtual Private Networks
controllable tunneling mechanism equivalent to a Frame Relay or ATM VC
Network Architecture and Design 22
Second Intermediate Report Multicast Routing (Focus on Internet Technology)
Doukas Multicast Routing (Focus on Wireless Technologies)
Kikilis MBONE
Mavrogenis IntServ (Focus on IntServ Implementation)
Klaoudatou IntServ (Focus on support of IntServ over other
technologies, i.e., ATM, wireless) Barbarousis
Diffserv (Focus on Diffserv Implementation) Ratsiatos
Network Architecture and Design 23
Second Intermediate Report Diffserv (Focus on support of DiffServ over other
technologies, i.e., ATM, DVB) Panoutsakopoulos
Integration of IntServ and Diffserv Lizos
MPLS (Focus on Routing) Kolovou
MPLS (Focus on Admission Control) Baliotis
SLAs/SLSs Rekleitis
Protocols for inter-BB communication Plataniwtis
Network Architecture and Design 24
Second Intermediate Report
Structure Overview of examined technology Focus on open research points Related to open points works - State of the
art behind open points Your own interests - Ideas Conclusions References
Network Architecture and Design 25
Second Intermediate Report
Report (soft and hard copy) A related presentation (about twenty
minutes) Usage of Greek language Deadline: 26/04/03