taming anycast in a wild internet - sigcomm · 2019. 11. 11. · taming anycast in a wild internet...

Taming Anycast in a Wild Internet

Stephen McQuistinUniversity of GlasgowVerizon Digital Media Services

Sree Priyanka UppuMarcel Flores Verizon Digital Media Services

2

192.0.2.0/24192.0.2.0/24

San Jose, CA Denver, CO

3

4

Performance is impacted by taking longer routes to a farther site

35ms

36ms

45ms

IP anycast

AS A AS A

5

Site 1 Site 2

IP anycast

Peer X

Transit Z

AS A AS A

Site 1 Site 2

6

IP anycast

AS BPeer X

Transit Z

AS A AS A

Site 1 Site 2

7

IP anycast

AS BPeer X

Transit Z

AS A AS A

Site 1 Site 2

8

Desirable route/site is via Z to Site 2

IP anycast

AS BPeer X

Transit Z

AS A AS A

Site 1 Site 2

9

… but AS B takes route through X to Site 1

IP anycast

AS BPeer X

Transit Z

AS A AS A

Site 1 Site 2

Opaque, upstream provider policies determine end-user performance

10

How do anycast operators influenceinbound routing?

Example

12

• Impact of adding a new peer is significant: two thirds of affected ASes see RTTs more than half

Announcement configurations

13

Site 1 Site 2 Site 3 Site 4 Site 5 …

Transit B

Transit C

Transit D

Peer E

Peer F

Peer G

…

Announcement configurations

14

Site 1 Site 2 Site 3 Site 4 Site 5 …

Transit B

Transit C

Transit D

Peer E

Peer F

Peer G

…

Announcement configurations

15

Site 1 Site 2 Site 3 Site 4 Site 5 …

Transit B

Transit C

Transit D

Peer E

Peer F

Peer G

…

Many-provider networks have a larger announcement configuration space

Many-provider networks

16

Many-provider networks

17

DNS root servers

Many-provider networks

18

A large commercial CDN

Many-provider networks

19

A large DNS provider

Many-provider networks

20

Many-provider networks

21

Few providers

Many-provider networks

22

Many providers

Many-provider networks

23

Many-provider networks

24

Many-provider networks generally have lower hegemony

Many-provider networks

25

Many-provider networks use a diversity of provider networks

What are the potential network impacts of altering announcement configurations?

Network impacts

27

AS A

192.0.2.0/24

TransitB

TransitC Transit

D

Control configuration: announcements to a limited set of

transit providers

Network impacts

28

AS A

198.51.100.0/24

TransitB

TransitC Transit

D

Experimental configuration: announcements to a limited set of transit providers and to nearly all

other providers

Peer E

Peer F

Peer G

Grouping vantage points

29

• Measurements taken from RIPE Atlas probes

• We don't want to rely on results from individual probes

• Group together, first by AS, then by geolocation

• More grouping functions evaluated in the paper

Control Experimental

Round-trip time impacts

30

�1.00 �0.75 �0.50 �0.25 0.00 0.25 0.50 0.75 1.00Relative Change

0.0

0.2

0.4

0.6

0.8

1.0

CD

F of

Gro

ups

�1.00 �0.75 �0.50 �0.25 0.00 0.25 0.50 0.75 1.00Relative Change

0.0

0.2

0.4

0.6

0.8

1.0

CD

F of

Gro

ups

Round-trip time impacts

31

Performance improves for 60% of groups

�1.00 �0.75 �0.50 �0.25 0.00 0.25 0.50 0.75 1.00Relative Change

0.0

0.2

0.4

0.6

0.8

1.0

CD

F of

Gro

ups

Round-trip time impacts

32

.. and degrades for 40% of groups

Catchment shift impacts

33

Catchment shift impacts

34

Majority of differences (and the greatest changes) come from groups that shift catchment

Catchment shift impacts

35

In the paper, we further explore performance impacts in terms of

paths taken and inbound providers

Who should we announce to for optimal performance?

DailyCatch

37

AS A

192.0.2.0/24

TransitB

TransitC Transit

D

Control configuration

AS A

198.51.100.0/24

TransitB

TransitC Transit

DPeer E

Peer F

Peer G

Experimental configuration

DailyCatch

38

AS A

192.0.2.0/24

TransitB

TransitC Transit

D

Control configuration

AS A

198.51.100.0/24

TransitB

TransitC Transit

DPeer E

Peer F

Peer G

Experimental configuration

DailyCatch

39

AS A

192.0.2.0/24

TransitB

TransitC Transit

D

Control configuration

AS A

198.51.100.0/24

TransitB

TransitC Transit

DPeer E

Peer F

Peer G

Experimental configuration

Snapshot A Snapshot B

DailyCatch

40

AS A

192.0.2.0/24

TransitB

TransitC Transit

D

Control configuration

AS A

198.51.100.0/24

TransitB

TransitC Transit

DPeer E

Peer F

Peer G

Experimental configuration

Snapshot A Snapshot B

Output: a net score and group-level scores

Scoring & Comparison

41

1 Take two snapshots

Control

Experiment

traceroute

Scoring & Comparison

42

2 For each group, assign a score, by passing the change in RTT through a logistic function

Control

Experiment

traceroute

Scoring & Comparison

43

3 Weight each group score by the volume of traffic it represents

Control

Experiment

traceroute

Scoring & Comparison

44

4 Sum for the overall score

Control

Experiment

traceroute ∑

45

Under the control configuration, probes are routed to San Jose

35ms

36ms

45ms

46

Under the experimental configuration, probes are routed to Denver

35ms → 21ms

36ms → 21ms

45ms → 20ms

Mixed impacts in North America

47

Mixed impacts in North America

48

Group size doesn’t correlate with observed RTT

Mixed impacts in North America

49

RTT changes are not uniform within a single AS

Mixed impacts in North America

50

More results and case studiesin the paper

Taming Anycast in a Wild Internet

51

• Anycast networks with many providers interact with the Internet in an observably different way than those with few providers

• This provides a configuration space of where and to who anycast announcements are given

• Announcement configurations can have significant network impacts

• DailyCatch enables a systematic, active measurement approach to configuration management