Transcript Mobile IP: Introduction - National Chi Nan University

Mobile IP: Quality-of-Service
Reference: “Domain based approach for QoS provisioning in mobile
IP”; Ki-Il Kim; Sang-Ha Kim; Proc. IEEE Global
Telecommunications Conference (GLOBECOM), 2001;
pp. 2230 –2234. (MobileIPQoS-4.pdf)
ISA Concept
• Integrated Services Architecture
– Intended to provide QoS transport support over
IP-based internets, RFC 1633
• Two broad categories of traffic on internet
– Elastic Traffic
 File transfer (FTP) , Email (SMTP), Remote Logon
(TELNET), Network management (SNMP), Web access
(HTTP)
– Inelastic Traffic
 Real-time traffic
 Throughput, Delay, Jitter, Packet loss
Background 2
ISA Approach
• Traditional (IP) Router mechanisms
– Routing algorithm
– Packet discard
• ISA Enhancements: the concept of flow
– Admission control: RSVP
– Routing algorithm: QoS-based OSPF
– Queuing discipline: For differing requirements
of different flow
– Discard policy: for managing congestion and
meeting QoS guarantees
Background 3
ISA Components
ISA Implemented in Router
Background 4
2-Level ISA Services
• 1. General categories of service
– Guaranteed
 Assured capacity/data rate
 Specified upper bound on the queuing delay
 No queuing loss
– Controlled Load
– Best effort
• 2. Service for a particular flow
– Traffic specification (TSpec): Token Bucket
– QoS
Background 5
Token Bucket Scheme
Background 6
Queuing Discipline
No priority; Larger mean delay
Greedy TCP connections crowd
out altruistic ones
Weighted Fair Queuing (WFQ)
Background 7
Resource ReSerVation Protocol
• Characteristics
– Unicast and Multicast
– Simplex
– Receiver-initiated reservation
– Maintaining soft state in the internet
– Providing different reservation styles
– Transparent operation through non-RSVP routers
– Support for IPv4 and IPv6
 Type-of-Service in IPv4
 Flow Label in IPv6
Background 8
RSVP Design Characteristics
• Receiver-initiated reservation
– Sender
 Provide the routers with the traffic characteristics of
the transmission (data rate, variability)
– Receiver
 Specify the desired QoS
– Router
 Aggregate multicast resource reservations for the
shared path segments along the distribution tree
• Soft State
Background 9
RSVP Data Flows
• Flow descriptor
– flowspec: desired QoS
– filterspec: defines the set of packets for the reservation
Treatment of packets of one session at one router
Background 10
RSVP Protocol Mechanisms
• Two message types
– Resv, Path
Background 11
RSVP Operation
Background 12
Differentiated Services (DS)
• Goal (RFC 2475)
– Provide a simple, easy-to-implement, lowoverhead tool to support a range of network
services (comparing with ISA)
• Key characteristics
– IP packets are labeled for differing QoS
treatment using the existing IPv4 Type-ofService octet or IPv6 Traffic Class octet. Thus,
no change is required to IP
Background 13
Differentiated Service (cont)
– A service level agreement (SLA) is established
between the service provider (internet domain)
and the customer prior to the use of DS
– All traffic with the same DS octet is treated the
same by the network service
– Routers deal with each packet individually and
do not have to save state information on
packet flows
Background 14
DS Octet
• Packets are labeled for service handling
by means of the DS octet
• Placed in the Type of Service field of an
IPv4 header, or the Traffic Class field of
the IPv6 header
• RFC 2474: The leftmost 6 bits form a DS
codepoint
• The DS codepoint is the DS label used to
classify packets for differentiated services
Background 15
DS Codepoint (6 bits)
• xxxxx0
– Reserved for assignment as standards
– 000000: default packet class, i.e. best-effort
– xxx000: reserved to provide backward
compatibility with the IPv4 precedence service
• xxxx11
– Reserved for experimental or local use
• xxxx01
– Reserved for experimental or local use, but
may be allocated for future standards action as
needed
Background 16
DS Domain
• Within a domain, the interpretation of DS codepoints
is uniform, consistent service is provided
Background 17
Routers in DS Domain
• Interior nodes (per-hop behavior: PHB)
– Queuing discipline to give preferential
treatment depending on codepoint value
– Packet-dropping rules to dictate which packets
should be dropped first in the event of buffer
saturation
• Boundary nodes
– PHB mechanisms
– Traffic conditioning functions
 metering, marking, shaping, dropping
Background 18
DS Traffic Conditioner
Background 19
DS Traffic Conditioner (cont)
• Classifier
– Separates submitted packets into different
classes
– Based on the DS codepoint or on multiple
fields within the packet header
• Meter
– Measures submitted traffic for conformance to
a profile
– Determines whether a given packet stream
class is within or exceeds the service level
guaranteed for that class
Background 20
DS Traffic Conditioner (cont)
• Marker
– Polices traffic by re-marking packets with a
different codepoint as needed
• Shaper
– Polices traffic by delaying packets as
necessary so that the packet stream in a given
class does not exceed the traffic rate specified
in the profile for that class
• Dropper
– Drops packets when the rate of packets of a
given class exceeds that specified in the
profile for that class
Background 21
ISA (IntServ) vs. DS (DiffServ)
Background 22
Introduction
• Tunneling mechanism in MIP causes serious
problems in adapting to the Internet QoS
architecture
– Integrated Service and Differentiated Service
– IntServ and DiffServ Identify the end-to-end
service session by address field of IP header
and port field of transport layer header
– Different sessions over tunneling section must
be defined
– Mapping the new section over IP tunnel to the
end-to-end service session must be defined
23
Related Work
• 1. New RSVP session over IP tunneling
section is created and is mapped to the
end-to-end RSVP session using IntServ
semantics
– Scalability problem remains
– As the number of mobile host is increased, the
session information per flow must be
maintained
– Implementation difficulties on existing network
24
Related Work (cont)
• 2. The edge router located on the tunneling
entry point remarks the DSCP in the IP
header to reflect settled service level
agreement
– DSCP: Differentiated Service Code Point
– Only qualitative QoS can be guaranteed,
quantitative QoS may not be guaranteed
sometimes
– Implementation difficulties on existing network
25
Related Work (cont)
• 3. The entire RSVP requests are aggregated
over tunneling
– Additional control message and state
information is needed (compared to the 2nd
mechanism)
– Be able to guarantee not only quantitative QoS
but also qualitative QoS
– Flow aggregation makes the number of the state
information small, the scalability problem can be
removed
– The paper is based on this mechanism
26
Two types of Mobility
• Micro mobility
• Macro mobility
– MIP
• The authors proposed the macro level
QoS guarantee mechanism
– The domain level agents and aggregate RSVP
signaling between them are defined for the
macro level QoS
27
Two issues on MIP QoS
• 1. How to guarantee QoS over a tunneling
section?
– Ref. [3]: The tunneling section is defined as the
new RSVP session from the ingress point to
the egress point
– Ref. [4] (based on [3]): The mobile host moves
to another FA. The HA sends the new RSVP
Path message to the FA in order to create the
new RSVP session over IP tunnel when the
periodical RSVP Update message arrived
28
Two issues on MIP QoS (cont)
• 2. How to guarantee seamless real-time
service regardless of handoff of a mobile
host?
– MRSVP (Ref. [5]): To minimize the effect of
host mobility, MRSVP reserve resources in
advance according to expected location, where
mobile hosts is expected to move
29
Example Configuration
Gateway router
30
Proposed Mechanism
• At least one aggregate RSVP session
must be created between the gateway
routers
– One gateway router must maintain the state
information as many as at least the number of
border gateway routers
 Since the domain number is limited as a constant
number, the scalability problem does not occur
– The small flows, which come from the access
network, must be mapped to several aggregate
flows between gateways
 Domain agent performs the functionality of
aggregating router or de-aggregating router
31
Proposed Mechanism (cont)
• In order to guarantee QoS for mobile hosts
– Each aggregated RSVP session between each
domain level agent reserves more bandwidth (l)
than the bandwidth actually being used now for the
further use
– Each HA checks periodically the bandwidth amount
of l. If l is lower than the initial amount, the HA can
detect that the new mobile host moves within its
own domain and the previously reserved bandwidth
is used. Then the HA sends the RSVP Path message
to the FA in order to reserve the bandwidth as much
as the currently used bandwidth + l
32
Dealing with mobility
33
Micro Level QoS
• 1. Applying the RSVP
– The end-to-end RSVP session consists of
several RSVP sessions
 From the sender to HA
 From HA to FA
 From FA to mobile host
– See the figure on next slide
34
Applying the RSVP in micro level
Individual Path/Resv
Aggregate Path/Resv
Individual Path/Resv
35
Micro Level QoS (cont)
• 2. Applying the DiffServ in Micro level QoS
– The FA must decide the DSCP according the
QoS requirement received in the registration
request message
– The FA must perform the functionality of
Bandwidth Broker (BB) in DiffServ
36
Feature Comparison
37
Simulation Topology
38
Simulation Parameters
39
Simulation Result: Uncontrolled
flow5
flow2
flow3
flow1
flow4
40
Simulation Result: Proposed
flow5
flow2
flow3
flow1
flow4
41
Simulation Result: Comparison
flow5 Delay_flow5
flow1
flow4
42
Conclusion
• Proposed scheme
– Macro level QoS
– Aggregation of RSVP flow
– Reserve more bandwidth in advance
43