0

IP QoS - General
Version IHL Type
Type of Service Total Length
Identification Flags Fragment Offset
COPS BGP LDP RSVP O
Time to Live Protocol Header Checksum IPv4 Header S
Source Address P
20
DestinationAddress
Address TCP UDP F
Source Port Destination Port

IP
0
AS ( = routing domain)
Version Traffic Class
TrafficClass Flow Label
The unit of router policy on the Internet. L2 / L1
Payload Length Next Header Hop Limit

One or more NWs cxontrolled by one administrator

Source Address
20
IPv6 Header Has a number of IP-prefixes and a unique AS number
Edge router OSPF (An IGP)
DestinationAddress
(ingress) R AS2 Used between routers within an AS
40 Exchanges FIB info with neighbours
Source Port Destination Port
AS1 R
IP packet R BGP (An EGP)
R
Flow R Announces reachable ASs
R R
A distinguable stream of packets from between or within AS
R R
a user, requiring the same QoS Jitter buffer SLA
Edge router R R
R A contract specifying metrics for
Admission Control (egress) AS3
R the service, e.g:
Allows usage of available resources Interior R
router Accessability (%), QoS
Assumes a Control Plane protocol (e.g. RSVP) parameters, Help desk-#, etc.
State information needed for the flow
A Best Effort router A CQS router
Traffic Engineering
to utilise the NW in a more efficient way. C Q S
Q
(FIFO)
Input Traffic Shaping
Output
ports port To delay packets in a traffic stream
Router Input Output
ports port
to conform it to a defined traffic profile.
A device linking networks together.
Marker
Can:
Sets the DSCP. (Compare ATM CLP!)
- Select a route
All traffic treated the same way, Can complement dropping.
- Forward or drop
One FIFO (first in, first out) queue Will perform for each packet: Packet Dropping
- Reorder or hold packets
at each congestion point - Classification:Used to identify Controlled discard of packets
- (re-) mark packets
Uses FIB for ’longest match a flow, e.g. Can be used to throttle TCP
algoritm’ by using the IP 5-tuple e.g. simple tail dropping, RED
Limitations: - Queueing: Policing / Filtering
- Processor power (central vs. - Scheduling: Selects the queue A Filter implements
distributed) to transmitt from Policies on incoming
- Interface capacity or outgoing packets

Leaky Bucket Token Bucket

Packets added at arrival b Add token r times/s AS Autonomous System

BGP Border Gateway Protocol
Maximum b packet in bucket Maximum b tokens in bucket CQS
DSCP
Classification, Queueing, Scheduling
Diffserv Code Point
Packets sent at rate r T A packet gets a token if avaliable EGP Exterior Gateway Protocol
FIB Forwarding Information Base
FIFO First in, first out
IGP Interior Gateway Protocol
r bucket rate = 1/T r token rate OSPF
R
Open Shortest Path First
Router

IPQ_SF_1 b bucket depth b bucket depth RED

SLA
Random Early Detection
Service Level Agreement