Routing as a Service - PowerPoint PPT Presentation

1 / 41
About This Presentation
Title:

Routing as a Service

Description:

Efficiency: replicate packets multiple times along a physical link; inefficient ... BBW = k*p/d1, where k = deg of replication ... – PowerPoint PPT presentation

Number of Views:44
Avg rating:3.0/5.0
Slides: 42
Provided by: karthiklak
Category:
Tags: bbw | routing | service

less

Transcript and Presenter's Notes

Title: Routing as a Service


1
Routing as a Service
  • Karthik Lakshminarayanan
  • (with Ion Stoica and Scott Shenker)
  • Sahara/i3 retreat, January 2004

2
Problem
  • Applications demand greater flexibility in route
    selection
  • Resilience RON, Tapestry
  • Performance Detour
  • Applications need different routing functionality
  • Multicast ESM, Overcast
  • DDoS defense SOS, Mayday
  • Anycast Gia
  • Difficult to change any routing-level component
    in the Internet today!

3
Current approach
  • Overlay networks
  • Layer above IP
  • Deployability
  • Problems
  • Ossification overlay solutions again ossify
    routing in the protocol hard to modify once
    deployed on large scale (lessons from the
    Internet)
  • Efficiency replicate packets multiple times
    along a physical link inefficient route
    construction
  • Lack of control for ISPs traffic hard for ISPs
    to control circumvent ISPs policies

4
Routing in transportation network
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
Our thesis
  • Push routing out of infrastructure
  • Argument for edge-controlled routing
  • Related NIRA (NewArch group, MIT/ISI)
  • Our contribution
  • Fine-grained control over routing
  • Control plane for achieving this

9
System architecture
  • Forwarding infrastructure
  • Provides basic routing (referred to as default
    routing)
  • Exports primitives for inserting routes

10
System architecture
  • 2. NEWS/Route selector
  • Aggregates network information
  • Selects routes on behalf of applications

11
System architecture
  • 3. End-hosts
  • Queries NEWS to setup paths

12
Architectural position
Infrastructure
Host
Data plane
Internet Infrastructure overlays
Control plane
P2P End-host overlays
Data plane
Control plane
Our proposal
Data plane
Control plane
  • Separate control plane and data plane by using
    clean abstractions

13
Challenges
  • Open, multi-provider system (design of
    primitives)
  • Unlike intra-domain, e.g. GSMP
  • Security control provided should not be used for
    attacking the system
  • Trust between entities of the system, e.g. what
    information does system give to NEWS
  • Large-scale system (route selection)
  • Scalability monitoring service to end-hosts
  • Stability should not lead to oscillations
  • Deployability ISP control

14
Infrastructure primitives
  • Label-switching-like primitive
  • Allows insertion of forwarding entries (id1,
    id2), where id1, id2 are labels
  • id NodeID LocalID
  • Establishing paths Loose virtual path (LVP)
  • Composition of label switches T (id1, id2, ,
    idn) is composed as (id1, id2), , (idn-1, idn)
  • Construct different topologies
  • Aggregation can be performed at the level of
    tunnels that end at infrastructure nodes

15
1. Trust
  • Infrastructure provides network information to
    NEWS
  • Verification NEWS should be able to verify this
  • Indirect measurement techniques using primitive
    alone
  • Metrics Delay, loss, bandwidth

16
1. Trust
  • NEWS provides routes across the network
  • Verification Network verifies correctness

17
2. Scalability
  • Monitoring
  • Monitor a subset of links
  • Update period depends on stability (exploit link
    stationarity)
  • For e.g., updates can be sent when metric on the
    link changes by a factor of x
  • Computation
  • Incremental computation of best paths
  • Multiple paths are returned
  • Querying
  • Default paths are used if special routing is not
    needed
  • Hierarchical dissemination
  • Caching of results TTL chosen to reflect
    stability of paths

18
3. Deployment
  • Infrastructure nodes
  • Hosted at certain points within ISPs
  • NEWS/Route selection
  • 3rd party provider like Akamai
  • Few in number
  • Determined by application requirements
  • Trust relations
  • NEWS trusts infrastructure for information
    (verifiable)
  • ISPs trust paths that NEWS returns (verifiable)
  • Export links that obey the underlying policy
    constraints

19
Implementation status
  • i3 primitives for setting up forwarding state
  • Distributed NEWS implemented
  • Route computation based on delay, loss and
    bandwidth
  • Deployed on PlanetLab
  • i3 proxy has been modified to query NEWS
  • Legacy applications can be used with NEWS

20
Summary of results
  • Verification of measurement techniques
  • Delay 97 of cases have error lt 10
  • Loss-rate 90 in over 80 of the cases
  • Bandwidth Within a factor of 1.5 in 60 of cases
  • Scalability of monitoring
  • Simulation-based
  • Logarithmic-degree graph
  • Achieve 90 RDP of 2.3 (for delay) for TS-16384

21
Summary
  • Routing control pushed outside the infrastructure
  • Routes computed by third-party entities (NEWS)
    along with measurement information provided by
    the infrastructure
  • Leads to evolvable networks
  • Deploy new routing schemes or optimize existing
    routing without changing the infrastructure

22
Backup slides
23
NEWS Round-trip delay
n1
n2
  • Use path selection primitive to send packet m
    along R?n1?R
  • Use path selection in conjunction with packet
    replication to send packet along R?n1?n2?n1?R
  • Difference yields the RTT of the link (n1?n2)

To measure RTT(n1?n2)
24
NEWS Measuring loss rate
n2
n1
  • Forwarding links
  • (n11? n21)
  • (n11 ? R)
  • (n21 ? n12)
  • (n21 ? R)
  • (n12 ? R)

R
To measure loss(n1?n2)
25
NEWS Measuring loss rate
n1
n2
  • Forwarding links
  • (n11? n21)
  • (n11 ? R)
  • (n21 ? n12)
  • (n21 ? R)
  • (n12 ? R)

To measure loss(n1?n2)
26
NEWS Measuring loss rate
n2
n1
  • m2 used to differentiate loss on (n1?n2) from
    that on (n2?n1)
  • (m ? m1 ? m2) ? loss on virtual link (n1?n2)
  • False positives
  • False negatives
  • Probability of false positives/negatives O(p2 )

R
To measure loss(n1?n2)
27
NEWS Available bandwidth
n2
n1
  • Delay-based bandwidth measurement (TCP Vegas
    like)
  • Increase sending rate till increase in delay is
    seen

cwd1
cwd2
cwd4
R
T received time sent time T smallest RTT
seen thus far
28
NEWS Available bandwidth
n2
n1
  • Use packet replication to identify if the
    bottleneck is on (n1?n2) or not

cwd2
cwd3
R
T received time sent time
29
NEWS Available bandwidth
n2
n1
  • Use packet replication to identify if the
    bottleneck is on (n1?n2) or not

cwd2
R
T received time sent time
30
NEWS Bottleneck bandwidth
n2
n1
Bottleneck
  • Packet-pair-like technique

R
31
NEWS Bottleneck bandwidth
n2
n1
  • BBW kp/d1, where k deg of replication
  • More the degree of replication, greater is the
    possibility of error
  • Intervening packets would affect this

Bottleneck
R
32
1. Trust
  • Problem Verify network information (delay, loss,
    bandwidth) provided by the network
  • Partial trust relations between the third party
    (NEWS) that computes routes and the
    infrastructure
  • Solution Ability to measure network
    characteristics using the simple label-switching
    primitive alone
  • Infrastructure cannot differentiate data packets
    and measurement packets

33
2. Security
  • Problem To prevent construction of illegitimate
    forwarding graphs using the primitives (e.g.
    loops)
  • Implicit mechanisms
  • Cryptographic constraints on successive
    forwarding labels (described in Secure-i3)
  • Protects against forming loops, confluences in
    the forwarding graph
  • Explicit mechanisms
  • NEWS servers ensure that computed paths are legal
  • NEWS signs the paths that it returns
  • Infrastructure trusts NEWS and inserts the signed
    paths
  • Can verify the validity of the paths that NEWS
    returns

34
Scalability
  • Multiple vantage points for measurements/monitorin
    g
  • Maintain a subset of links
  • Division of overlay graph to reflect underlying
    paths

35
Scalability
  • 2-level hierarchy
  • Random partitioning of nodes into buckets
  • Maintain few edges within the same bucket
  • Maintain few edges to every other bucket
  • If bucket size is vN, each measurement point
    responsible for only O(vN) links

36
Implementation status
  • i3 primitives are used as the infrastructure
    primitives
  • Distributed NEWS is implemented and can perform
    route computation based on delay, loss and
    bandwidth
  • i3 proxy has been modified to query NEWS
  • Legacy applications can be used with NEWS

37
Evaluation
  • Effectiveness of indirect measurements
  • Planetlab experiments
  • Scalability techniques

38
NEWS Delay Estimation
  • More than 97 of the samples have error lt 10
  • If we consider median over 10 consecutive
    samples, 99.3 of the samples have error lt 10

39
NEWS Loss-Rate Estimation
  • Accuracy of 90 in over 80 of the cases that
    have loss rate more than 0.1
  • Performs well in identifying high lossy links

40
NEWS Avail-BW Estimation
  • Compare with stable TCP bandwidth
  • Measurement points are classified on the basis
    of distance of two targets from the source of
    measurement
  • Relative error lt 0.5 in 60 of the cases
  • Underestimates for Far-Far
  • Overestimates for Far-Close in some cases

41
Scalability
RG Random gh PRG Proximity random gh HRG
Hierarchical random gh Transit stub
network 16384 nodes Average node degree 20
  • Delay based route selection
  • 90th percentile RDP is 2.33 (HRG), 3.74 (RG) and
    1.16 (PRG)
Write a Comment
User Comments (0)
About PowerShow.com