Transcript Slide

Does it have to be that complicated? Thoughts on
a next-generation Internet
Henning Schulzrinne
Internet Real Time Laboratory
Computer Science Dept., Columbia University, New York
http://www.cs.columbia.edu/IRT
Overview
• The transformation in keynote “big
pictures”
• The transition in cost metrics
• What has made the Internet successful?
• Some Internet problems
• Simplicity wins
• Architectural complexity
• New protocol engineering
COMSWARE (Jan. 2006)
2
Philosophy transition
One computer/phone,
many users
mainframe era
home phone
party line
PC era
cell phone era
One computer/phone,
one user
Many computers/phones,
one user
~ ubiquitous computing
right place (device),
right time,
right media
anywhere,
any time
any media
COMSWARE (Jan. 2006)
3
Evolution of VoIP
“how can I make it
stop ringing?”
long-distance calling,
ca. 1930
“amazing – the
phone rings”
1996-2000
“does it do
call transfer?”
going beyond
the black phone
catching up
with the digital PBX
2000-2003
COMSWARE (Jan. 2006)
20044
Transition in cost balance
• Total cost of ownership
– Ethernet port cost  $10
– about 80% of Columbia CS’s system support cost is
staff cost
• about $2500/person/year  2 new PCs/year
• much of the rest is backup & license for spam
filters 
• Does not count hours of employee or son/daughter time
• PC, Ethernet port and router cost seem to have reached
plateau
– just that the $10 now buys a 100 Mb/s port instead of
10 Mb/s
COMSWARE (Jan. 2006)
5
What has made the Internet successful?
•
•
•
•
•
36 years  approaching mid-life crisis  time for
self-reflection
–  next generation suddenly no longer finds it
hip
Transparency in the core
– new applications
Narrow interfaces
– socket interface, resolver
• HTTP and SMTP messaging as applications
– prevent change leakage
Low barrier to entry
– L2: minimalist assumptions
– technical: basic connectivity is within
– economical: below $20?
Commercial off-the-shelf systems
– scale: compare 802.11 router vs. cell base
station
COMSWARE (Jan. 2006)
Ethernet
web server
6
IP “hourglass”
email WWW phone...
SMTP HTTP RTP...
TCP UDP…
IP
ethernet PPP…
CSMA async sonet...
copper fiber radio...
COMSWARE (Jan. 2006)
Steve Deering,
IETF Aug. 2001
7
User issues (guesses)
•
•
•
•
Lack of trust
– small mistakes  identity gone
– waste time on spam, viruses, worms, spyware, …
Lack of reliability
– 99.5% instead of 99.999%
– even IETF meeting can’t get reliable 802.11 connectivity
Lack of symmetry
– asymmetric bandwidth: ADSL
– asymmetric addressing: NAT, firewalls  client(-server) only,
packet relaying via TURN or p2p
Users as “Internet mechanics”
– why does a user need to know whether to use IMAP or POP?
– navigate circle of blame
COMSWARE (Jan. 2006)
8
Technical infrastructure issues
• Sensor networks
– addressing mechanisms not suitable geographic
addressing, self-routing packets
– TCP model
– partial and temporal connectivity
• Mobile ad-hoc networks (MANET
– address acquisition?
• Mobile networks (e.g., plane [Connexion], train, car, …)
– routing granularity: each plane a BGP AS?
– network merging and splitting
COMSWARE (Jan. 2006)
9
Technical infrastructure issues
• Multi-homing and mobility
– address vs. locator issues
• Large-scale Internet
– secure routing
– routing scaling (60,000 AS)
• Architecture
– standardization delays  now routinely 3-5 years for
minor extensions
– resistance to change at ≤ L4
– difficulty in deploying new applications:
• Internet service = outbound port 80 and 443
COMSWARE (Jan. 2006)
10
What has gone wrong?
•
•
•
•
•
Familiar to anybody who has an old house…
Entropy
– as parts are added, complexity and interactions increase
Changing assumptions
– trust model: research colleagues  far more spammers and
phishers than friends
• AOL: 80% of email is spam
– internationalization: internationalized domain names, email
character sets
– criticality: email research papers  transfers $B and dial “9-11”
– economics: competing providers
• “Internet does not route money” (Clark)
Backfitting
– had to backfit security, I18N, autoconfiguration, …
 Tear down the old house, gut interior or more wall paper?
COMSWARE (Jan. 2006)
11
In more detail…
•
•
•
•
•
Deployment problems
Layer creep
Simple and universal wins
Scaling in human terms
Cross-cutting concerns, e.g.,
– CPU vs. human cycles
• we optimize the $100 component, not the
$100/hour labor
– introspection
– graceful upgrades
– no policy magic
COMSWARE (Jan. 2006)
12
The transformation of protocol stacks
Internet
ca. 1995
Internet
ca. 2005
application
presentation
session
application
application
SOAP
HTTP
transport
TCP
TCP
network
IP
IP-in-IP
IP
H. Zimmermann
ca. 1980
link
802.3
physical
physical
COMSWARE (Jan. 2006)
MPLS, PoE
PoS, ATM
physical
13
Cause of death for the next big thing
QoS
multicast
not manageable across competing
domains

not configurable by normal users
(or apps writers)

no business model for ISPs


no initial gain

80% solution in existing system


mobile
IP

active
networks
IPsec
IPv6
















(NAT)
increase system vulnerability


COMSWARE (Jan. 2006)


14
Simple wins (mostly)
•
•
Examples:
– Ethernet vs. all other L2 technologies
– HTTP vs. HTTPng and all the other hypertext attempts
– SMTP vs. X.400
– SDP vs. SDPng
– TLS vs. IPsec (simpler to re-use)
– no QoS & MPLS vs. RSVP
– DNS-SD (“Bonjour”) vs. SLP
– SIP vs. H.323 (but conversely: SIP vs. Jabber, SIP vs. Asterisk)
– the failure of almost all middleware
– future: demise of 3G vs. plain SIP
Efficiency is not important
– BitTorrent, P2P searching, RSS, …
COMSWARE (Jan. 2006)
15
Measuring complexity
•
•
•
Traditional O(.) metrics rarely helpful
– except maybe for routing protocols
Focus on parsing, messaging complexity
– marginally helpful, but no engineering metrics for trade-offs
No protocol engineering discipline, lacking
– guidelines for design
– learning from failures
• we have plenty to choose from – but hard to look at our own
(communal) failures
– re-usable components
• components not designed for plug-and-play
• “we don’t do APIs”  we don’t worry about whether a simple
API can be written that can be taught in Networking 101
COMSWARE (Jan. 2006)
16
Measuring complexity
• Conceptual complexity
– can I explain the protocol operation in one class?
– e.g., counter examples PIM-SM, MADCAP, OSPF
• Observable vs. hidden
– one side can see, without “god box”
– hidden state and actions increase information
complexity
• unknown variables can have any state
• Number of system interfaces
– see BISDN, 3GPP, NGN, …
COMSWARE (Jan. 2006)
17
Possible complexity metrics
•
•
•
•
•
new code needed (vs. reuse)  less likely to be buggy or have buffer
overflows
– e.g., new text format almost the same
– numerous binary formats
– security components
new identities and identifiers needed
number of configurable options + parameters
– must be configured & can be configured (with interop impact)
– discoverable vs. manual/unspecified
– SIP experience: things that shouldn’t be configurable will be
– RED experience: parameter robustness
– mute programmer interop test: two implementations, no side
channel
number of “left-to-local policy”
– DSCP confusion
start-up latency (“protocol boot time”)
– IPv4 DAD, IGMP
COMSWARE (Jan. 2006)
18
Democratization of protocol engineering
•
Traditional Internet application protocols (IETF et al.):
– one protocol for each type of application:
• SMTP for email, ftp for file transfer, HTTP for web access,
POP for email retrieval, NNTP for netnews, …
• slow protocol development process
• re-do security (authentication) for each
• each new protocol has its own text encoding
– similarity across protocols: SMTP-style headers
» Content-Type: text/plain; charset="us-ascii";
format=flowed
•
– large parsing exposure  new buffer overflows for each
protocol
Separate worlds:
– most of the new protocols in the real world based on WS
– IETF stuck in bubble of one-off protocols  more fun!
• re-use considered a disadvantage
• insular protocols that have local cult following (BEEP)
COMSWARE (Jan. 2006)
19
The transformation of protocol design
•
•
•
•
One application, one protocol  common infrastructure for new
application
Old model:
– RPC for corporate “one-off” applications
– custom protocols for common Internet-scale applications
Far too many new applications
– and not enough protocol engineers
– network specialist  application specialist
– new IETF application protocol design takes ~5 years
Many of the applications (email to file access) could be modeled as
RPC
custom
text
protocol
(ftp)
ASN.1based
(SNMP,
X.400)
RFC 822 protocol
(SMTP, HTTP, RTSP,
SIP, …)
use XML for
protocol bodies
COMSWARE (Jan. 2006)
(IETF IM &
presence)
SOAP and
other XML
protocols
20
Why are web services succeeding(*) after RPC failed?
•
•
•
SOAP = just another remote procedure call mechanism
– plenty of predecessors: SunRPC, DCE, DCOM, Corba, …
– “client-server computing”
– all of them were to transform (enterprise) computing, integrate
legacy applications, end world hunger, …
Why didn’t they?
Speculation:
– no web front end (no three-tier applications)
– few open-source implementations
– no common protocol between PC client (Microsoft) and backend
(IBM mainframes, Sun, VMS)
– corporate networks local only (one site), with limited backbone
bandwidth
COMSWARE (Jan. 2006)
(*) we hope
21
Why did web services succeed after RPC failed?
• More speculation:
– Corba, DCOM, SunRPC: no real security story
• had custom-made security instead of TLS
– Many initially designed for LAN only
• e.g., use of UDP, service naming by ports only
– Limited language support
• e.g., no PHP or Perl support for Corba
– Limited platform support
• DCOM = Microsoft
• Corba = all-but-Microsoft
COMSWARE (Jan. 2006)
22
Technical challenges for web services
•
•
•
•
Resistance to common protocol
infrastructure
“Yet another RPC fad”
SOAP overhead = the price of generality:
– SOAP envelope
– inefficient binary encoding (images,
etc.) compared to MIME multipart
– klumsy load-balancing and
redundancy
– inefficient implementations
• high start-up costs
XML problems
– XML schema hard to work with
– Namespace clutter
– hard to extend among multiple
independent parties ( RelaxNG)
• can only do <any ##other>
COMSWARE (Jan. 2006)
SOAP
PHP
servlets
23
Emerging light-weight alternatives
• Many SOAP services, but public services are often XMLRPC only
– or even HTTP POST
• Examples:
– eBay, Amazon, Google
– Ajax
• Reasons?
– SOAP envelope adds modest value
– Scripting languages have
– REST principles: identify objects by URL in request,
not by identifier in RPC body
• easier dispatch to PHP/Ruby/… scripts
COMSWARE (Jan. 2006)
24
Time for a new protocol stack?
• Now: add x.5 sublayers and overlay
– HIP, MPLS, TLS, …
• Doesn’t tell us what we could/should do
– or where functionality belongs
– use of upper layers to help lower layers (security associations,
authorization)
– what is innate complexity and what is entropy?
• Examples:
– Applications: do we need ftp, SMTP, IMAP, POP, SIP, RTSP, HTTP,
p2p protocols?
– Network: can we reduce complexity by integrating functionality
or re-assigning it?
• e.g., should e2e security focus on transport layer rather than
network layer?
– probably need pub/sub layer – currently kludged locally (email,
IM, specialized)
COMSWARE (Jan. 2006)
25
NSF “Green Field” approach
•
•
US National Science Foundation (NSF) working on new funding thrust
 next-generation Internet
– idea: incremental components  new architecture
– vs. traditional “brown field” approach
Two major components
– GENI: large-scale experimental testbed for testing nextgeneration ideas
• building on PlanetLab (hundreds of public-access servers) 
p2p, CDN, measurement infrastructures
• probably offers circuits (optical or virtual with bandwidth
guarantees)
• ~$300M (not yet allocated)
– FIND:
• regular research program within NETS ($15m)
• prepare architecture designs
COMSWARE (Jan. 2006)
26
NSF: FIND and GENI, cont’d
• Fundamental notions:
– not constrained by existing Internet architecture
• Difficulties:
– not coordinated  too many moving pieces?
– no single research team can do everything
– point optimization: Internet for
– benchmarks missing
• how do you compare architectures?
• are there quantifiable requirements?
• are there metrics to compare different approaches?
• Cynic’s prediction based on the past:
– IPv6: “you’ll get security, QoS, autoconfiguration,
mobility, …”
– IPv4: “good ideas, I’ll do those, too”
COMSWARE (Jan. 2006)
27
(My) guidelines for a new Internet
•
•
Maintain success factors, such
as
– service transparency
– low barrier to entry
– narrow interfaces
New guidelines
– optimize human cycles,
not CPU cycles
– design for symmetry
– security built-in, not
bolted-on
– everything can be mobile,
including networks
– sending me data is a
privilege, not a right
– reliability paramount
– isolation of flows
•
New possibilities:
– another look at circuit
switching?
– knowledge and control
(“signaling”) planes?
– separate packet forwarding
from control
– better alignment of costs and
benefit
– better scaling for Internetscale routing
– more general services
COMSWARE (Jan. 2006)
28
More “network” services
• Currently, very specialized and limited
– packet forwarding
– DNS for identifier lookup
– DHCP for configuration
• New opportunities
– packet forwarding with control
– general identifier storage and lookup
• both server-based and peer-to-peer
– SLP/Jini/UDDI service location  ontology-based data
store
– network file storage  for temporarily-disconnected
mobiles
– network computation  translation, relaying
– trust services ( IRT trust paths work)
COMSWARE (Jan. 2006)
29
Security
• More than just encryption!
• Need identity and role-based certificates
• May want reverse-path reachability (bank  customer)
asking
user
network
user
do I know this person?
is he a likely sender of
spam?
is this really a bank?
am I connected
to a “real”
network or an
impostor?
network is this a customer?
COMSWARE (Jan. 2006)
is this BGP
route
advertisement
legitimate?
30
Summary
• Traditional protocol engineering
– “must do congestion control”
– “must do security”
– “must be efficient”
• New module engineering
– must reduce operations cost
– out-of-the-box experience
– re-usable components
• most protocol design will be done by domain
experts (cf. PHP vs. C++)
• What would a clean-room design look like?
– keep what made Internet successful
– generalize & adjust to new conditions
COMSWARE (Jan. 2006)
31
Henning Schulzrinne
Dept. of Computer Science
Columbia University
July 2005
Managing (VoIP) Applications – DYSWIS
Overview
• User experience for VoIP still inferior
• Existing network management doesn’t work for
VoIP and other modern applications
• Need user-centric rather than operator-centric
management
• Proposal: peer-to-peer management
– “Do You See What I See?”
• Also use for reliability estimation and statistical
fault characterization
COMSWARE (Jan. 2006)
33
VoIP user experience
• Only 95-99.5% call attempt success
– “Keynote was able to complete VoIP calls 96.9% of the time,
compared with 99.9% for calls made over the public network.
Voice quality for VoIP calls on average was rated at 3.5 out of 5,
compared with 3.9 for public-network calls and 3.6 for cellular
phone calls. And the amount of delay the audio signals
experienced was 295 milliseconds for VoIP calls, compared with
139 milliseconds for public-network calls.” (InformationWeek,
July 11, 2005)
• Mid-call disruptions
• Lots of knobs to turn
– Separate problem: manual configuration
COMSWARE (Jan. 2006)
34
Diagnostic undecidability
• symptom: “cannot reach server”
• more precise: send packet, but no response
• causes:
– NAT problem (return packet dropped)?
– firewall problem?
– path to server broken?
– outdated server information (moved)?
– server dead?
• 5 causes  very different remedies
– no good way for non-technical user to tell
• Whom do you call?
COMSWARE (Jan. 2006)
35
Circle of blame
probably packet
loss in your
Internet connection 
reboot your DSL modem
ISP
VSP
OS
must be a
Windows registry
problem  re-install
Windows
probably a gateway fault
 choose us as provider
app
vendor
COMSWARE (Jan. 2006)
must be
your software
 upgrade
36
Traditional network management model
X
SNMP
“management from the center”
COMSWARE (Jan. 2006)
37
Old assumptions, now wrong
• Single provider (enterprise, carrier)
– has access to most path elements
– professionally managed
• Typically, hard failures or aggregate problems
– element failures
– substantial packet loss
• Mostly L2 and L3 elements
– switches, routers
– rarely 802.11 APs
• Indirect detection
– MIB variable vs. actual protocol performance
• No real end system management
– DMI & SNMP never succeeded
– each application does its own updates
COMSWARE (Jan. 2006)
38
Example VoIP: managing the protocol stack
media
RTP
UDP/TCP
IP
echo
gain problems
VAD action
protocol problem
playout errors
protocol problem
authorization
asymmetric conn
(NAT)
SIP
TCP neg. failure
NAT time-out
firewall policy
no route
packet loss
COMSWARE (Jan. 2006)
39
Example VoIP: call lifecycle view
STUN
failure
auth?
registrar
?
outbound
proxy?
dest.
proxy?
COMSWARE (Jan. 2006)
loss?
gain?
silence
suppression?
40
Types of failures
• Hard failures
– connection attempt fails
– no media connection
– NAT time-out
• Soft failures (degradation)
– packet loss (bursts)
•access network? backbone? remote
access?
– delay (bursts)
•OS? access networks?
– acoustic problems (microphone gain,
echo)
COMSWARE (Jan. 2006)
41
Examples of additional problems
• ping and traceroute no longer works reliably
– WinXP SP 2 turns off ICMP
– some networks filter all ICMP messages
• Early NAT binding time-out
– initial packet exchange succeeds, but then TCP
binding is removed (“web-only Internet”)\
• policy intent vs. failure
– “broken by design”
– “we don’t allow port 25” vs. “SMTP server
temporarily unreachable”
COMSWARE (Jan. 2006)
42
“Do You See What I See?”
• Each node has a set of active and passive
measurement tools
• Use intercept (NDIS, pcap)
– to detect problems automatically
• e.g., no response to HTTP or DNS request
– gather performance statistics (packet jitter)
– capture RTCP and similar measurement packets
• Nodes can ask others for their view
– possibly also dedicated “weather stations”
• Iterative process, leading to:
– user indication of cause of failure
– in some cases, work-around (application-layer
routing)  TURN server, use remote DNS servers
• Nodes collect statistical information on failures and
their likely causes
COMSWARE (Jan. 2006)
43
Failure detection tools
• STUN server
– what is your IP address?
• ping and traceroute
• Transport-level liveness
– open TCP connection to
port
– send UDP ping to port
media
RTP
UDP/TCP
IP
COMSWARE (Jan. 2006)
44
Need failure statistics
• Which parts of the network are most
likely to fail (or degrade)
– access network
– network interconnects
– backbone network
– infrastructure servers (DHCP, DNS)
– application servers (SIP, RTSP, HTTP,
…)
– protocol failures/incompatibility
• Currently, mostly guesses
• End nodes can gather and accumulate
statistics
COMSWARE (Jan. 2006)
46
Conclusion
•
•
•
•
•
Internet middle-aged  time for reflection
can we keep what has worked and re-consider the others?
need to work on control, management and reflection
opportunity for new building blocks vs. classical
middleware
opportunity
COMSWARE (Jan. 2006)
47