routing und flow control im internet der zukunft routing and flow
TRANSCRIPT
www3.informatik.uni-wuerzburg.de
Institute of Computer Science
Department of Distributed Systems
Prof. Dr.-Ing. P. Tran-Gia
Routing und Flow Control im Internet der Zukunft
–
Routing and Flow Control in the Future Internet
Michael Menth
2Routing and Flow Control in the Future Internet
Michael Menth
Outline
Two major problems of routing in the Internet
Depletion of available IPv4 addresses
– Solution: IPv6
– Interworking IPv6 – IPv4
– Deployment
Growth of the routing tables in the DFZ
– Causes
– Solutions: principles of future Internet routing
Flow control in the future Internet
Pre-congestion notification (PCN)
Admission control and flow termination
Conclusion
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Depletion of Free IPv4 Address Pool
IANA (Internet Assigned Numbers Authority)
Projected depletion of unallocated IPv4 address pool: 28.01.2011
IPv4
Address format: 4 bytes ~ 4.3×109 addresses
8,4 addresses per km2 earth surface
Structure: 132.187.12.123
IPv6
Address format: 16 bytes ~ 3.4×1038 addresses
6,67 × 1017 addresses per mm2 earth surface
Structure: 2001:DB8:0:0:8:800:200C:417A
Prefix notation: 132.187/16: 16 bits prefix (~ address block)
Interworking problems
IPv6 addresses unknown to legacy applications, hosts, and routers
Dual-stack (IPv4 and IPv6) required
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IPv4 – IPv6 Interworking Principles: Tunneling
IPv6 traffic tunneled through IPv4 networks
IPv4 IPv6IPv6
B Data
AB
B DataB DataY
X Y
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IPv4 – IPv6 Interworking Principles: Address Conversion
Conversion between IPv4 and IPv6 addresses
132.187.12.123
0:0:0:0:0:ffff:Hex(132.187.12.123)
Applicable only to actual IPv4 addresses
Conversion between IPv4 headers and IPv6 headers
Stateless IP/ICMP translation (SIIT)
IPv6IPv4 IPv4
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Problem
Real IPv6 address not
convertible into IPv4 address
Network address port translation (NAPT)
IPv4 border router converts
– From IPv6 address and port
– Into other IPv4 address and port and back
Example
IPv4 – IPv6 Interworking Principles: NAPT
IPv6 IPv4
NAPT
[A]:1234 [C]:80
[C]:80 [A]:1234
B:5678 C:80
C:80 B:5678
NAPTIPv6 IPv4
[A]:1234 B:5678src dst src dst
Request
Response
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Planned and Actual Deployment of IPv6
Observation
IPv6 hardly adopted
Limited reachability for early
adopters
Source: presentation by G.
Huston and G. Michalson
(APNIC) at RIPE 56 in Berlin,
May 2008
Other partial solution to IPv4 address
depletion
Private networks behind NATs
10/8, 172.16/12, 192.168/16
Planned deployment of IPv6 Actual deployment of IPv6
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IPv4 Outage Experiment at IETF71
IPv4 outage experiment at IETF71 in Philadelphia
(13.03.2008)
IPv6 Internet is only a very small fraction of IPv4
Internet
Most portals do not offer services over IPv6
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The Internet: a Network of Networks
Tier 1 ISP
Tier 1 ISP
Tier 1 ISP
NAP
Tier-2 ISPTier-2 ISP
Tier-2 ISP Tier-2 ISP
Tier-2 ISP
local
ISPlocal
ISP
local
ISP
local
ISP
local
ISP Tier 3
ISP
local
ISP
local
ISP
local
ISP
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Basic BGP Information
BGP information
132.187.0/20 AS-Path: AS338, AS20978
132.187.16/20 AS-Path: AS574, AS231, AS339, AS448
132.187.20/22 AS-Path: AS574, AS1079, AS2098, AS3172
…
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Problem 2: Growth of Routing Table Sizes in the DFZ
IPv4 FIB entries from 01.07.1988 – 16.05.08 (AS2)
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Causes for Increasing FIB Sizes in DFZ (1)
Provider independent addressing
Longest prefix match
Maximum length of propagated prefixes: /24
Provider A Provider B
85.178.0.0/16
85.178.4.0/23
96.103.0.0/16
85.178.4.0/23
DFZ
x
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Causes for Increasing FIB Sizes in DFZ (2)
Multihoming
Provider A Provider B
85.178.0.0/16
85.178.4.0/23
96.103.0.0/16
85.178.4.0/23
DFZ
85.178.4.0/23
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Causes for Increasing FIB Sizes in DFZ (3)
Traffic engineering
Provider A Provider B
85.178.0.0/16
85.178.4.0/23
96.103.0.0/16
85.178.4.0/23
DFZ
85.178.5.0/24 85.178.6.0/24
Incoming
VoIP
Incoming
data
85.178.4.0/23
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Causes for Increasing FIB Sizes in DFZ (4)
Countermeasure against prefix hijacking
Announcement of longer prefixes than necessary
E.g. YouTube prefix hijacking incident by Pakistan Telecom (24.02.08)
Source: RIPE56
AS36561
Pakistan
Telecom
AS17557
208.65.152.0/22 208.65.153.0/24
YouTube
AS3491
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Solution 1: Tweaking the Current Interdomain Routing (1)
Aggregation proxies
Core router-integrated overlay
(CRIO)
The aggregation proxy
announces a short prefix
instead of many long
prefixes.
Packets addressed to
the long prefixes are
routable in the DFZ
They are forwarded to
the aggregation proxy
which tunnels them to
their destination
network.
X.Y.0/24 X.Y.1/24 X.Y.2/24 X.Y.3/24
X.Y.0/22
Statically
configured
tunnels
X.Y.0/22
X.Y.0/22X.Y.0/22
Aggregation
proxy announces
short prefixes
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Solution 1: Tweaking the Current Interdomain Routing (2)
Retain long prefixes and provide
lookup system for direct tunnels
Tunneling route reduction
protocol (TRRP)
Some long prefixes are not
announced to BGP, therefore,
they are not routable in the DFZ.
The lookup system provides a
router for them in the destination
AS such that corresponding
packets can be tunneled,
decapsulated, and forwarded
from there to their destination via
intradomain routing.
X.Y.Z/24
Lookup system
for non-routable
addresses
X.Y
.Z/2
4
Border router
with routable
address
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Solution 2: Locator/Identifier Split
Separation of IP addresses
Identifier
Locator
Mapping function
Identifier locator
Objective
Limit growth of routing tables
Open issues
Mapping system
Exact implementation of Loc/ID
BProvider X
Provider Y
A
Locator(B)Data B
Mapping
service
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Incremental Deployment of Loc/ID for the Internet
Locator ID separation protocol
(LISP)
Cisco‘s proposal within RRG
of IRTF
Local
routing
domain
Gateways
Global
routing
domain
Mapping service
supported by
local caches
12
34
A
B
C
DIdentifiers
Locators
Communication 1 4:
1 sends packet with address 4 to A,
A sends packet with address D4 to D,
D sends packet with address 4 to 4.
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Interworking between the Legacy and the Future Internet
Global routing
domain and
legacy Internet
Local
routing
domain
Proxy
gateway
GatewayLegacy
node
1
AB
Communication 1 B:
1 sends packet with address B to A,
A sends packet with address B to B.
Communication B 1:
B sends packet with address 1 to C,
C sends packet with address A1 to A,
A sends packet with address 1 to 1.
C
Mapping service
supported by
local caches
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Clean Slate Approach for Loc/ID
Identifier (2)
Local locator (LL(2)=b)
Local mapping service
Local
mapping
service
b
2
Data
ID=2
LL(2)=b
a
1
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LL=b
Clean Slate Approach for Loc/ID
Global locator (GL(3)=C)
Global mapping service
LL=cGlobal
mapping
service
Data
ID=3
GL(3)=C
LL for next
jump to C
added using
local routing
tablesData
ID=3
LL(3)=f added
by ingress node
using local
mapping service
b c d e
A B C
Identifier (2)
Local locator (LL(2)=b)
Local mapping service
f
3
Local
mapping
service
a
1
LL=dLL=eLL(3)=f
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Solutions for Improved Scalability
Locator ID separation protocol LISP
Different mapping implementations
Distributed hash table LISP-DHT
Alternative, logical topology LISP-ALT
Content overlay network service LISP-CONS
A not-so-novel EID to RLOC database LISP-NERD
A practical tunneling architecture eFIT-APT
Six/One Router with DNS-based resolution system Six/One
Dynamic internetworking architecture DYNA
Tunneling route reduction protocol TRRP
Internet vastly improved plumbing Ivip
Host identity protocol architecture HIP
Global, site, and end-system address elements GSE
Node identity interworking architecture
Hierarchical routing architecture HRA
New inter-domain routing architecture NIRA
IP with virtual link extension IPvLX
Core router-integrated overlay CRIO
Geographically informed inter-domain routing GIRO
On Compact Routing for the Internet
…
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Pre-Congestion Notification (PCN) –
Flow Control for the Future Internet
Simple support for quality of service (QoS)
No per-flow states inside a network
Admission control
Proactive: keep traffic load low to avoid congestion
High priority transport only for explicitly admitted flows
Block further flows if traffic load is already high
Flow termination
Terminates some admitted flows
Only for exceptional cases
Reactive: reduce traffic load if it is too high due to an accicent
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0
Pre-congestion
type
Impact on
AC and FT
No pre-
congestion
Admissible
rate AR(l)
Admit new flows
PCN rate
r(l)
on link l
AR-pre-
congestionBlock new flows
Supportable
rate SR(l)
SR-pre-
congestion
Block new flows
Terminate someadmitted flows
Pre-Congestion Notification (PCN) – Concept
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PCN Domain
RSVPCapacity
Overprovisioning
Source Destination
End-to-end
flow
PCN ingress
node
PCN egress
node
Router with signalling
functionality
Router with metering &
marking functionalityMMS
S/MM
MM
S
End-to-end
resource
signalling
S/MM
S
S
Edge-to-Edge Pre-Congestion Notification (PCN)
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PCN DomainSource
End-to-end
flow
Router with metering &
marking functionality
Destination
MM
MM
MM
MM
MMMM
MM
End-to-End Pre-Congestion Notification (PCN)
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Conclusion
Pre-congestion notification (PCN)
Packet marking
Admission control
Flow termination
Edge-to-edge and end-to-end PCN
Two major problems in today’s routing
Depletion of available IPv4 address pool
Growth of routing tables
IPv6
Interworking methods with IPv4
No incentive for early adopters
Hardly used
Loc/ID split
Promising design principle for routing scalability
Incremental deployment e.g. LISP
Clean slate Loc/ID
What’s routing like in the Internet in 2020?