Transcript Smart IP Switching

Smart IP Switching
A Hybrid System for Fast IP-based Network
Backbones
David Lloyd
Donal O’Mahony
IP over ATM
 Conventional IP routers have become a bandwidth bottleneck
 ATM technology offers high bandwidth capability
 IP over ATM schemes have been developed to support IP over
and ATM Network
•Classical IP over ATM
•Next Hop Resolution Protocol (NHRP)
•LAN Emulation (LANE)
•Multi-Protocol Over ATM (MPOA)
Heavyweight Nature of Emulation Techniques
IP Network
Emulation Scheme
ATM Network
Overlay Model
IP on ATM Hardware
 IP implemented directly on ATM hardware
 Schemes may be categorised by the approach they employ for setting up
switched paths through a network
 Principal Approaches are:
•Traffic-Driven
- Nature of traffic drives switch path establishment
- (Ipsilon’s IP Switching and Toshiba’s CSR)
•Control-Driven
- Switched paths set up before data traffic flows
- (Cisco’s Tag Switching and IBM’s ARIS)
Traffic-Driven Approaches
Advantages
Switched paths are only set up for long-lived flows
Schemes are non-complex
Resilient in event of failure
Scalable
Disadvantages
Flow aggregation is not an inherent property of the scheme
Short-lived Flows that recur consistently can cause excessive control traffic
Flow Merging in Control-driven Schemes
VC Merge
The merging of one or more incoming VCs into the same outgoing VC
Requires special VC merge-capable ATM hardware
VP Merge
The merging of one or more incoming Virtual Paths (VPs) onto the same
outgoing VP
It is imperative to ensure that active VCs are not merged
Block allocation of VCIs Required
AAL-5 Cell Interleave
AAL-5 PDU A
ATM Cells
Node 1
Virtual Channel
ATM Cells
Node 3
Virtual Channel
Node 2
ATM Cells
AAL-5 PDU B
Virtual Channel
Node 4
Control-Driven Approaches
Advantages
No delay in setting up a dedicated VC on a flow by flow
basis
All IP packets are switched at layer 2
Disadvantages
Dedicated-VCs are established for all routes
Schemes are Complex
Multi-Protocol Label Switching
In early 1997 the IETF Multi-Protocol Label Switching (MPLS) working group
was established.
The group issued a framework document, which attempts to:
Provide a coherent description of the major approaches
Discuss the technical issues involved
Lay the way forward for standardisation
Introduction to Smart IP Switching
Smart IP Switching is a new traffic-driven scheme that exhibits advantages of both
the traffic-driven and control-driven approaches.
The main benefits of Smart IP Switching are:
The Introduction of flow aggregation into a traffic-driven scheme
The definition of short-term and long-term VCs
Increasing the proportion of IP packets switched at layer 2
Smart IP Switching Concepts
The key concepts that define Smart IP Switching are:
Unique Flow Identifier - Flow Identification
Flow aggregation - Based on CIDR prefixes
Ingress-piping - Merging flows at an ingress node
Virtual Merge - Merging flows at intermediate nodes
Longevity of VCs - short-term and long term VCs
Flow Identification
Unique Flow Identifier (UFI)
flow type
flow identifier
prefix mask
The Unique Flow Identifier identifies Ipsilon flow types plus a
new flow type (flow type 3)
Flow type 3 is specifically defined to represent aggregate flows
Smart IP Switch Representation
Smart IP Switch Controller
Flow
Information
Base (FIB)
Residual FIB
(RFIB)
Pseudo IP
Module
routing
table
Controller
Functions
forwarding
engine
write-down operations
and control of switch
fabric
write-up operations
switch fabric
ipswitch port
ipswitch port
ipswitch port
ipswitch port
Smart IP Switch Operation (1)
first packet
first packet
P2
SIPS1
P1
first packet
Default VC
P1
P2
SIPS2
IFMP REDIRECT
Default VC
first packet
P1
SIPS3
P2
IFMP REDIRECT
IFMP REDIRECT
LAN1
Default VC
P1=port 1
P2=port 2
SIPS Operation (First Packet)
P1
LAN1
P2
P1
SIPS2
VCI=32
P1
P2
VPI=0
VPI=0
Ingress-pipe
Default VC
Default VC
Default VC
SIPS1
Ingress-pipe
VCI=32
SIPS Operation (Dedicated VCs)
SIPS3
P2
VPI=0
VCI=32
Smart IP Switch Operation (2)
second packet
LAN1
P2
P1
P1
SIPS2
SIPS3
P1
P2
P2
VPI=0
VPI=0
VPI=0
Ingress-pipe
Default VC
Default VC
Default VC
SIPS1
VCI=32
VCI=32
VCI=32
second packet
SIPS Operation (Second packet)
P1
LAN1
Default VC
Default VC
SIPS1
P2
P1
SIPS2
VPI=0
VPI=0
Ingress-pipe
SIPS3
P1
P2
VCI=32
VCI=32
Cut-through
second packet
SIPS Operation (First Cut-through)
Down-piping
P2
VPI=0
VCI=32
Smart IP Switching Operation (3)
P1
LAN1
Default VC
Default VC
SIPS1
P2
P1
SIPS2
VCI=32
Ingress-pipe
P2
VPI=0
VPI=0
VPI=0
Ingress-pipe
SIPS3
P1
P2
VCI=32
VCI=32
VCI=33
VCI=33
second packet
Cut-through
SIPS Operation (Second Cut-through)
Cut-through
Ingress-pipe at Intermediate Node
FDDI : LAN
P1=port 1
P2=port 2
P1
LAN1
Default VC
Default VC
SIPS1
P2
P1
SIPS2
Ingress-pipe
P2
VPI=0
VPI=0
VPI=0
VCI=32
SIPS3
P1
P2
VCI=32
VCI=32
VCI=33
VCI=33
VCI=35
Cut-through
SIPS Operation (Intermediate Ingress-Pipe)
Virtual Merge
ingress node
P1
P2
SIPS1
ingress-pipe
LAN1
P1
SIPS2
P1
P2
SIPS3
egress node
Dedicated VC
next available VC
Dedicated VC
P1
SIPS4
P2
ingress-pipe
P2
virtual merge
LAN2
SIPS Operation (Virtual Merge)
P1=port 1
P2=port 2
default VCs omitted
for clarity
Ingress-Piping
SIPS4
LAN1
LAN3
SIPS1
SIPS2
10/100 Mb Ethernet
links
LAN2
10 Mb Ethernet LAN
SIPS3
network :172.16.0.0
Flow Management
Flow Information Base (FIB) used to manage flows
Ipsilon flow types are created and refreshed as normal
Detection of a potential aggregate flow is based existence of a CIDR prefix
Flow type 3 is refreshed by sending an REDIRECT message with a redirect
message element attached for every upstream ingress-pipe that remains active
Referesh of VCs is managed on a localised scope
Longevity of VCs
The first time a flow is detected, it is set up as short-term
A VC used by many flows is transitioned to long-term
VCs for flows that recur are set up as long-term
Long-term VCs do not have to be refreshed as often as short-term VCs
VC Pool
 The use of a VC pool eliminates the delay incurred in setting up a VC
 A suitable strategy to manage VC pool size must be employed
 VCs may be expensive
 Packets arriving on an unassigned VC must be associated with the relevant
flow type 3
 The use of a VC pool has been discussed in the literature
CIDR Fall-back
Routing table entry
172.16.0.0
Routing table entry
172.16.0.0
P1
LAN1
Default VC
Default VC
SIPS1
Routing table entry
172.16.3.0
SIPS3
SIPS2
P2
P1
VPI=0
VCI=32
Based on UFI prefix
172.16.0.0
P1
P2
P2
VPI=0
VCI=32
Based on UFI prefix
172.16.3.0
Network: 172.16.3.0
Host:
172.16.3.1
CIDR-Fall-back (2)
Routing table entry
172.16.0.0
Routing table entry
172.16.0.0
P1
LAN1
Default VC
Default VC
SIPS1
Routing table entry
172.16.3.0
SIPS3
SIPS2
P2
P1
P1
P2
P2
VPI=0
VPI=0
VCI=32
VCI=32
Network: 172.16.3.0
VCI=33
Based on UFI prefix
172.16.3.0
Based on UFI prefix
172.16.3.0
Host:
172.16.3.1
Simulated Network
altavista.com
204.123.2.69
webcrawler.com
198.3.101.102
disney.com
208.218.3.1
mit.edu
www-vbns.reston.mci.net.net
ieee.org
204.70.133.152
199.172.136.1
www.cise.nfs..gov
ncsa.uiuc.edu
SIPS, or Router (Not Implemented)
SIPS(Implemented)
Simulated ATM Link(Implemented)
Simulated ATM Link(Not Implemented)
Non-existent or Sink Port
206.235.18.81
141.142.3.16
vvv.nsf.gov
206.235.18.84
18.69.0.27
Boston.mci.net
pointcast.com
205.228.184.6
204.189.128.177
QUB
SanFrancisco.mci.net
204.189.216.153
193.1.195.90
man.ja.net
netscape.com
207.200.71..20
204.189.128.178
microsoft.com
heuston.hea.ie
207.68.137.64
204.189.216.152
193.1.195.249
192.121.154.230
193.1.195.29
connolly.hea.ie
ebone.london
193.1.195.250
cisco.tcd.ie
193.1.195.30
193.1.194.18
UCG
140.203.0.0
193.1.194.26
TCD
134.226.0.0
UL
136.201.0.0
193.1.194.110
193.1.194.18
UCD
DCU
136.206.0.0
137.43.0.0
IP Packet
Monitoring Device
Simulation Results
IP Switching
Smart IP Switching
54.0%
7.1%
99.2%
1.4%
50.6%
2.5%
95.1%
9.5%
TEST-SET1
Percentage IP Packets Switched at Layer 2
Percentage of control traffic overhead
TEST-SET2
Percentage IP Packets Switched at Layer 2
Percentage of control traffic overhead
Summary
Smart IP Switching:
Is a new traffic-driven IP on ATM hardware scheme modelled on Ipsilon’s IP
Switching
Introduces Flow Aggregation into the traffic driven-scheme
Introduces the concept of short-term and long-term VCs
Significantly increases the proportion of IP Packet that are diverted from being
forwarded (layer 3) to being switched (layer 2)
- A performance level that is comparable to that of the control-driven approaches, while
retaining the simplicity, scalability and reliability of the traffic-driven approach