Archive for the 'Internet Outages' Category

Under the Telescope: Time Warner Cable Internet Outage

Friday, August 29th, 2014 by Vasco Asturiano

In the early hours of August 27th 2014, Time Warner Cable (TWC) suffered a major Internet outage, which started around 9:30am and lasted until 11:00am UTC (4:30am-6:00am EST). According to Time Warner, this disconnect was caused by an issue with its Internet backbone during a routine network maintenance procedure.

A few sources have documented the outage based on BGP and/or active measurements, including Renesys and RIPE NCC. Here we present a view from passive traffic measurement, specifically from the UCSD Network Telescope, which continuously listens for Internet Background Radiation (IBR) traffic. IBR is a constantly changing mix of traffic caused by benign misconfigurations, bugs, malicious activity, scanning, responses to spoofed traffic (backscatter), etc.  In order to extract a signal usable for our inferences, we count the number of unique source IP addresses (in IBR observed from a certain AS or geographical area) that pass a series of filters. Our filters try to remove (i) spoofed traffic, (ii) backscatter, and (iii) ports/protocols that generate significant noise.

Most of TWC’s Autonomous Systems seem to have been affected during the time of the reported outage. Our indicators from the telescope show a total absence of traffic from TWC’s ASes, indicating a complete network outage.

Figure 1: Number of unique IBR source IPs (after filtering) observed per minute for the TWC ASes

Figure 1 shows the number of unique source IPs originated by TWC ASes per minute, as observed by the network telescope; we plot only TWC ASes from which there was any IBR traffic observed just before and after the event. For reference, these ASes are: AS7843, AS10796, AS11351, AS11426, AS11427, AS11955, AS12271 and AS20001.

TWC is a large Internet access provider in the United States, and this IBR signal can also reveal insight into the impact of this outage across the country. Figure 2 shows the same metric as Figure 1, but for source IPs across the entire country, indicating a drop of about 12% in the number of (filtered) IBR sources, which suggests that during the incident, a significant fraction of the US population lost Internet access.

Figure 2: Number of unique IBR source IPs (after filtering) observed in the US 

Drilling down to a regional level shows which US states seem to have suffered a larger relative drop in traffic.

Figure 3: Decrease ratio of unique IBR source IPs per US state 

Figure 3 compares the number of IBR sources observed in the 5 minute-interval just before the incident (9:25-9:30UTC) to the 5-minute interval after it (9:30-9:35UTC). The yellow to red color gradient represents the ratio at which a certain state’s IBR sources have decreased (redder means larger drop). States that did not suffer a substantial relative decrease are shown in yellow. This geographical spread is likely correlated with market penetration of TWC connectivity within each state.

 

 

Syria disappears from the Internet

Wednesday, December 5th, 2012 by Alistair King and Alberto Dainotti

On the 29th of November, shortly after 10am UTC (12pm Damascus time), the Syrian state telecom (AS29386) withdrew the majority of BGP routes to Syrian networks (see reports from Renesys, Arbor, CloudFlare, BGPmon). Five prefixes allocated to Syrian organizations remained reachable for another several hours, served by Tata Communications. By midnight UTC on the 29th, as reported by BGPmon, these five prefixes had also been withdrawn from the global routing table, completing the disconnection of Syria from the rest of the Internet.

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Unsolicited Internet Traffic from Libya

Wednesday, March 23rd, 2011 by Emile Aben

Amidst the recent political unrest in the Middle East, researchers have observed significant changes in Internet traffic and connectivity. In this article we tap into a previously unused source of data: unsolicited Internet traffic arriving from Libya. The traffic data we captured shows distinct changes in unsolicited traffic patterns since 17 February 2011.

Most of the information already published about Internet connectivity in the Middle East has been based on four types of data:

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