The Top Outages of 2023: Analyses and Takeaways

Featured Speakers
IanWaters
EMEA Marketing Director
Mike Hicks
Principal Solution Analyst

3
© 2024 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
BeforeWe Begin…
• If you have any questions, please type them in the Questions window.
• If you have any audio problems, please chat us for help.
• A recording of this presentation will be sent to you in a few days.
• Interested in more outage analysis and Internet insights? Check out the ThousandEyes blog and The
Internet Report podcast.

Anatomy of an Outage
• Understanding different types of
Internet outages is important to mitigate
their impact.
• Outages can vary in blast radius, be
planned or unplanned, and have varying
MTTR.
• Network outages depend on where the
problem occurs, with transit network
incidents impacting multiple providers.
• Tracking outages can help teams
identify patterns and prevent customer
service disruptions.

Outage and Degradation Impacts
BGP
ISP
CDN
DNS SaaS Apps
Services
APIs
Data Center
Cloud
DDoS
Protection
SSE
RISKAND
COMPLIANCE
Is our traffic
getting routed out
of region?
SERVICE
AVAILABILITY
Which cloud
regions are
impacted?
SITUATIONAL
AWARENESS
Are regional ISPs
spoofing our DNS
records?
SERVICE
RECOVERY
Did we
successfully
cut over to
our DDoS
mitigation
service?
NETWORK
SECURITY
Are SASE routing
policies working
as we expect?
CUSTOMER
SUPPORT
Is an Internet
outage preventing
users from reaching
our service?
WORKFORCE
PRODUCTIVITY
Will our Salesforce
dev updates degrade
performance
for some global users?
$32,000
$120,000
$3,500
3474
REVENUE
PROTECTION
Is the payment
gateway down
or just
unreachable?

2023 Outages by the Numbers: ISP Compared to CSP
• ThousandEyes reported an increase in cloud service provider (CSP) outages in 2023.
• CSP outages are the second most common type of disruption after ISP outages.
• The ratio of CSP outages to ISP outages increased in 2023.

2023 Outages by the Numbers:
U.S.-centric Outages in Relation to Global Outages
• U.S.-centric outages increased to 37% in 2023 from 34% in 2022.
• Smaller, contained outages are becoming more common.
• Localized outages have different impacts and require different responses compared to global outages.

2023 Outages by the Numbers: Application Outages
• The number and frequency of application outages have been on the rise over the past year.
• Application-related disruptions can have a bigger impact than network outages, though they are not as common.

Connections Are Complex
Branch Office
Employee
BYOD
Corp devices
IOT
Cameras and
sensors
IoT
VDI
People, places,
and things
Edge
BYOD
Data Center
IOT
Core
network
Mobile
networks
Core
network
Peering
Access
networks
Wireless
network
Wireless
gateway
DNS
Cloud
and SaaS
Cloud
providers
Datacenter
infrastructure
Cloud connectivity
Direct
connect
ISP transit
providers
SaaS
onramp

8
3
9
3
5
4
6
8
6
Correlate
performance
across every layer
Time Correlated

Microsoft
(1/25)
Outlook
(2/7)
Virgin Media
(4/4)
AWS
(6/13)
Slack (8/2)
Square
(9/8)
Workday +
Cloudflare (11/2)
2023 Outage Timeline
Purple = Application Outage
Red = Network Outage
Blue = Infrastructure Outage
Bookmark the InternetOutages
Timeline for outage updates
throughout the year.

Microsoft 365 (1/25/23)
• Microsoft started experiencing service related issues around 07:05
AM (UTC).
• The disruption was triggered by an external BGP change
by Microsoft that impacted connected service providers
• Microsoft BGP prefixes were withdrawn completely
but then almost immediately re-advertised.
• Affected smaller (/24) prefixes and summary prefixes (/12).
• Cascading impact on global routing tables, causing significant
churn.
• Prefixes were either withdrawn or re-advertised to
transit providers.
• Large amount of packet loss were seen as well as
HTTP and DNS timeouts.
• Timeouts seen in the application “Response,” further indicating the
effect of the network on service availability.

Microsoft Outlook (2/7/23)
• Starting around 03:55 UTC,
Outlook became unavailable.
• Network path was working
properly, butThousandEyes
observed elevated server response
timeouts and slow page loading.
• Majority of the errors were HTTP
server timeouts, indicating an
application issue.
• Incident was mostly concentrated
in the U.S. and lasted ~2 hours.

Virgin Media (4/4/23)
• From approximately 00:30 to 17:30 UTC,
two outages impacted the reachability of
Virgin Media UK’s network and services.
• The first incident began at approximately
00:30 UTC and appeared to coincide with a
series of BGP route withdrawals.
• Second incident was shorter, but the
networks experienced similar BGP and
reachability issues.
• Outages were overnight and due to the
repeat nature, could indicate maintenance
issues.

AWS (6/13/23)
• Outage impacted services within US-EAST-1.
• Lasted two hours and increased latency,
server timeouts, and HTTP server errors were
observed.
• AWS console access was also affected,
making troubleshooting difficult.
• AWS confirmed the issue was due to a
capacity management subsystem failure.
• Organizations leveraging cloud services, such
as those offered byAWS, should be aware of
the relationships in their digital ecosystem,
regardless of whether those relationships are
services or networks.

Slack (8/2/23)
• Application outage that lasted from 4:01 PM
to 6 PM (UTC).
• Network paths and accessibility were
unaffected.
• Initially could be seen as HTTP 500 errors and
higher-than-normal page load times.
• During the outage, users were unable to
upload files or share screenshots.
• Root cause—work on a “routine database
cluster migration”—that accidentally reduced
database capacity to the point that it could
not support a regularly scheduled job
running.

Square (9/8/23)
• Outage lasted over 18 hours.
• Backend issue that prevented the
platform from processing payment
transactions.
• Users reported various problems,
from terminal connections dropping
out, to payments appearing to
complete but then not showing up
in business accounts.
• ThousandEyes observed
intermittent dropouts and 503
‘service unavailable’ errors.

Workday + Cloudflare (11/2/23)
• Cloudflare andWorkday
experienced a major outage due to
multiple infrastructure provider
failures.
• DR resources took 6 hours to come
online and full resolution took 36
hours.
• Initial cause was a partial mains
power outage at a Flexential data
center in Portland.
• Further generator and grid failures
resulted in a complete power loss
and ungraceful shutdown.

Takeaways
• Understanding how your application works is important for quickly identifying failures and making improvements.
• Just because your application is working doesn't mean it's functioning optimally.
• Knowing how all parts of the service work together is crucial for ongoing design and future optimizations.
• Improved visibility and operational optimizations can prevent outages and minimize their impact.
• Tracking different categories of outages and degradations over time can be helpful.

• Subscribe to our blog to keep up-to-date!
thousandeyes.com/blog/
• Tune in toThe Internet Report Podcast.
https://www.thousandeyes.com/the-internet-report/
20
Next Steps
• New tutorial videos on our features
thousandeyes.com/resources/?cat=tutorial
• New Getting Started Guides
docs.thousandeyes.com/product-documentation/getting-started
Blog and
Podcast
Learning
Resources
Support
Community
• Still have questions? Ask us on the ThousandEyes Support
Community AMA: http://bit.ly/2023Outages

Q&A
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The Top Outages of 2023: Analyses and Takeaways

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