1

Effects of Mediterranean Fibre Cuts seen by PingER, Jan. 30 2008

Prepared by: Les CottrellSLAC,Qasim LoneNIIT/SLAC

www.slac.stanford.edu/grp/scs/net/talk08/med_fibre_cut_jan08.ppt

2

Event• Jan 30 in the morning 2 fibre cuts in

Mediterranean reported by: etc. – Ships dragging anchors in storm– One near Alexandra, other near Marseille– Cut SEAMEWE4 and FLAG

Alexandria

Marseille

3

Effects• Traffic degraded to Middle East, S. Asia

Bangalore

Increase in RTT from 330ms to 550ms

Losses increase to 50%Most applications fail

RTT recovered Jan 31Losses recovered Feb 5

RT

T (

ms)

Lo

ss %

Effect starts between 6:47am and 7:16am GMT

4

Recovery• Traffic rerouted to use SEAMEWE3

or go Westwards

Effect often recovered from after 15-20 hours, complete recovery after 3 days

RT

T (

ms)

Lo

ss %

UAEEffect starts between

6:47am and 7:16am GMT

5

Impact on Region

Before = Jan-Sep 07, After = Jan 30th

(first 6 hours of Jan 30 are before event)Israel & Pakistan (cf. 2005) not affectedSudan, Egypt, India, Sri Lanka: factor 2-4 worseJordan, Oman, UAE, Nepal, Bhutan, and Bangladesh < 100kbps

After (Jan 30, ’08)Before (Jan-Sep ’07)

Throughput

6

Badly affected Hosts• 23 hosts in 13

countries impacted• Note the spike in

RTT on Jan 30th

• Many hosts recover on Jan 31st

• Affects: UAE, Bangladeshh, Bhutan, Djibouti, Indonesia, India, Jordan, Sri lanka, Maldives, Oman, Saudi Arabia, Thailand, Turkey

• Pakistan OK (cf. June 2005 SEAMEWE3 fibre cut, now has multiple terrestrial fibres) Country

RT

T (

ms)

Date

Average RTT seen from SLAC to hosts affected by the Mediterranean

Fibre Cuts Jan 30, 2008

7

Badly affected Hosts

• 29 hosts in 16 countries impacted

• Note the spike in RTT on Jan 30th

• Recovery can take days• Some hosts recover on

Jan 31st • Affects: UAE, Bangladesh,

Bahrain, Bhutan, Djibouti, Indonesia, India, Jordan, Sri Lanka, Maldives, Oman, Palestine, Qatar, Saudi Arabia, SudanThailand

• Pakistan OK (cf. June 2005 SEAMEWE3 fibre cut, now has multiple terrestrial fibres)

Co

un

try

Average RTT seen from SLAC to hosts affected by the Mediterranean

Fibre Cuts Jan 30, 2008

DateRTT (ms)

S A

siaM

id East

Africa

SE

Asia

Outage

8

Average RTTs Jan 29th and 30th

• Vertical axis chopped, can get to ~ 10 secs!

• 30 Hosts, 17 countries• Time of impact varies by 2-3

hours, 4am except Jordan• Impact is sudden

• Most Hosts continued to respond

– 4 hosts: 3 Sudan, 1 Bahrain unreachable for 1 hr ea.

• Magnitude of impact varies

Normal DayJan 29th 2008 Event day Jan 30th 2008

9

Recovery• Median RTT for impacted hosts

seen from SLAC– Stable prior to Jan 30th

– Increase by > factor 3 on Jan30th– Lot of host to host variability– Starting to recover by Jan 31st

Not all hosts in all countries in the region were impacted, e.g.

India: 2 of 8; Sri Lanka 3 of 5; Malvinas 3 of 5; Indonesia 1 of 7;Turkey: 1 of 3; Thailand 1 of 6.

On the other hand all monitored hosts were impacted in:

UAE(1), Bangladesh(2), Bharein(2), Djibouti(1), Jordan(4), Oman(1), Qatar(1), Saudi Arabia (2)

Non impacted countries in region also interesting, e.g.

Central Asia – using satellitePalestine – using SEAMEWE3Pakistan – alternate cablesIsrael – not using these cablesE. Asia – via the Pacific

10

RTT seen from ICTP Trieste• Fewer host

monitored

• Sudan recovers after 3 days,

• India recovering after 6 days

• Bangladesh no recovery sign

11

Recover from Loss• Number = % loss• Some

countries/sites normally poor

– Sudan 1 of 3– Oman– Bangladesh 1 of 2– Maldives 1 of 2

• Not all sites in a country affected:– Bahrain 1 out of 2– India 2 out of 4– Jordan 3 out of 4– Sri Lanka & Maldives

none

• Some countries take a long time (>5 days) to recover– Jordan, Bangladesh– India: 2 sites 4 days

Start of Outage

0 – 2.5% (acceptable)

>= 12% (unusable)

2.5-12% (poor)

Afr

ica

M E

ast

SE

Asi

aS

Asi

a

12

Jan 30th RTTs from SLAC• Vertical axis chopped,

can get to ~ 10 secs!• 30 Hosts, 17 countries• Time of impact varies

by 2-3 hours• Impact is sudden• Most Hosts continued

to respond– 4 hosts: 3 Sudan, 1

Bahrain unreachable

• Magnitude of impact varies

CountryR

TT

(ms)

Time of d

ay (GMT)

Average RTT from SLAC to various countriesOn January 30th 2008

Normal diurnalVariations Jan 29