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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
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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
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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
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RTT seen from ICTP Trieste• Fewer host
monitored
• Sudan recovers after 3 days,
• India recovering after 6 days
• Bangladesh no recovery sign
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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
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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