Modest networkingModest networking

Henning SchulzrinneColumbia University

MIND Workshop – London, Oct. 7, 2002Keynote Address

Joint work withMaria PapadopouliHannes Tschofenig

Xiaoming FuJochen Eisl

Robert Hancock*

(Opinions are the speaker’s and may not be shared by the co-authors…)

OverviewOverview

New Realism in networking Multimodal networking Some thoughts on QoS CASP – another attempt at QoS

signaling

New realismNew realism Old notion: build it and they will pay

“Don’t want to be just dumb bit carriers’’ Value add charge exorbitant fees for

shipping special bits Convergence all bits are similar

Cheapest bits win (unless monopolies or regulation interfere)

Almost all of networking is/will be a commodity – we should be proud of it!

Cost of networkingCost of networkingModality mod

espeed $/MB (= 1 minute of 64

kb/s videoconferencing or 1/3 MP3)

OC-3 P 155 Mb/s $0.0013

Australian DSL(512/128 kb/s)

P 512/128 kb/s

$0.018

GSM voice C 8 kb/s $0.66-$1.70

HSCSD C 20 kb/s $2.06

GPRS P 25 kb/s $4-$10

Iridium C 10 kb/s $20

SMS (160 chars/message) P ? $62.50

Motient (BlackBerry) P 8 kb/s $133

Spectrum cost for 3GSpectrum cost for 3G

Location what costUK 3G $590/person

Germany 3G $558/person

Italy 3G $200/person

New York Verizon(20MHz)

$220/customer

Generally, license limited to 10-15 years

Multimodal networkingMultimodal networking = use multiple types of networks, with

transparent movement of information technical integration (IP) access/business

integration (roaming) variables: ubiquity, access speed, cost/bit,

… 2G/3G: rely on value of ubiquity immediacy

but: demise of Iridium and other satellite efforts similar to early wired Internet or some

international locations e.g., Australia

Multimodal networkingMultimodal networking expand reach by leveraging mobility locality of data references

mobile Internet not for general research Zipf distribution for multimedia content

short movies, MP3s, news, … newspapers local information (maps, schedules, traffic

radio, weather, tourist information)

Multimedia data access Multimedia data access modalitiesmodalities

high low

high 7DS 802.11hotspots

low satelliteSMS?

voice (2G, 2.5G)

band

wid

th(p

eak)

delay

A family of access pointsA family of access points

Infostation

2G/3G

access sharing

7DS

hotspot + cache

WLAN

7DS options7DS options

Many degrees of cooperation server to client

only server shares data no cooperation among clients fixed and mobile information servers

peer-to-peer data sharing and query forwarding

among peers

7DS options7DS optionsQuery Forwarding

Host A Host B

query

FWquery

Host C

time

Querying

active (periodic)

passive

Power conservation

on

off time

communication enabled

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25

Density of hosts (#hosts/km )

Da

tah

old

ers

(%

) P2P data sharing(power cons.)

P2P data sharing

P2P data sharing & FW(power cons.)

Fixed Info Server

Mobile Info Server

high transmission power

2

Fixed Info Server

Mobile Info Server

P2P

Dataholders (%) after 25 Dataholders (%) after 25 minmin

Host B

Messagerelaying

Host A

messages

Gateway

WAN

Host AWLAN

WLAN

Message relaying with 7DSMessage relaying with 7DS

Quality of Service

Why QoS hasn’t happenedWhy QoS hasn’t happened need to admit failure – “bandwidth too cheap to meter” undemocratic: some traffic is more equal than other dishonest: we only talk about the beneficiaries reminds you of your mom: no, you can’t have that 10

Mb/s now socialist: administer scarcity - we like SUVs (or to drive

100 mph)! “risky scheme”: security exposure – reserve your whole

network niche only: displacement applications (such as

telephony) need QoS touchy-feely: requires cooperation edge-ISP, transit

ISPs, end systems snake oil: add QoS, lose half your router interface

bandwidth

What makes QoS hardWhat makes QoS hard No, it’s not RSVP scaling network has become harder to evolve:

network address translation firewalls high packetization overhead (VPNs, IPv6) nobody can be trusted

to be useful, has to be nearly universally supported (“no, you can’t make calls to AS 123”)

network QoS vs. business class model: “coach is empty, please refund fare”

almost all the time, reserved traffic gets same delay as best effort

applications will switch QoS classes

What makes QoS hardWhat makes QoS hard currently, the ISP interface is IP and BGP

– adding a third one is a big deal trust model ISP or cash model payment model completely unclear for

peering new Internet service model: TCP client

(inside) – server (outside) exception: peer-to-peer on college

campuses network to host: you first, no, you first

What is QoS, really?What is QoS, really? Network transparency

no loss (< 1%) very few delay spikes (< 1%) close to propagation delay

anything else is too hard to explain to users! QoS is just a facet of network reliability

consistent 5% packet loss is much better than 5% probability that network is unavailable for seconds

users are willing to pay for availability traditional QoS may help availability during outage

periods e.g., MCI/UUnet breakdown 10/3/02 DOS attacks failure of load distribution links

CASP = Cross-Application CASP = Cross-Application Signaling ProtocolSignaling Protocol RSVP is being used for lots of things beyond

flow setup: RSVP TE, midcom, … Complex and monolithic

multicast support multiple reservation styles killer reservations and error handling receiver-orientation only non-RSVP region handling interface complexity (LIH)

fairly closely ties QoS to RSVP hard to extract generic signaling protocols

CASP as modular signaling protocol currently a proposal for IETF NSIS group

What is CASP?What is CASP? Generic signaling service

establishes state along path of data one sender, typically one receiver

can be multiple receivers multicast can be used for QoS per-flow or per-class reservation also: firewall setup, TE, programmable networks,

configuration, topology exploration, … avoid restricting users of protocol (and religious

arguments): sender vs. receiver orientation more or less closely tied to data path

router-by-routernetwork (AS)

CASP network model – on-CASP network model – on-pathpath

CASP nodes form CASP chain not every node processes all client protocols:

non-CASP node: regular router omnivorous: processes all CASP messages selective: bypassed by CASP messages with unknown client

protocols

QoS

midcom

QoS QoS

selective

omnivorous

CASP chain

CASP network model – out-CASP network model – out-of-pathof-path

Also route network-by-network can combine router-by-router with

out-of-path messaging

AS 1249 AS15465 AS17

Bandwidth broker

NAC CASP

data

CASP protocol structureCASP protocol structure

client layer does the real work: reserve resources open firewall ports …

messaging layer: establishes and tears down state negotiates features and capabilities

transport layer: reliable transport

client layer

(C)

messaging layer

(M)

transport layer

(T)

scout protocol

UDP

IP router alert

messaging layer

(M)

CASP

Next-hop discoveryNext-hop discovery Next-in-path service

enhanced routing protocols distribute information about node capabilities in OSPF

routing protocol with probing service discovery, e.g., SLP first hop, e.g., router advertisements DHCP scout protocol

Next AS service touch down once per autonomous system (AS) new DNS name space: ASN.as.arpa, e.g., 17.as.arpa use new DNS NAPTR and SRV for lookup

similar to SIP approach

Mobility and route Mobility and route changeschanges

avoids session identification by end point addresses avoid use of traffic selector as session identifier remove dead branch

discovers new route

on refresh

ADD

B=2

DEL (B=2)

B=1

ConclusionConclusion

Until wireless bits are too cheap to meter, try hiding lack of universal high bit density from user

QoS is a reliability mechanism CASP as a new signaling platform