3. Focused Research (2)COVID-19’s Impact on FLET’S Traffic

3.1 Introduction

staying in, there was a sudden paucity of faces on the

The COVID-19 situation prompted the closure of Japan’s

streets. Trends in FLET’S traffic underwent a clear change

schools nationwide from March, resulting in a sharp rise infrom March 2. Later, on March 25, the Tokyo government

people working remotely from home. The changes in many

began urging people to stay indoors. Japan declared a statepeople’s Internet usage patterns put a strain on individualof emergency covering seven prefectures on April 7, andservices and communication links, and social media wasthis was expanded nationwide on April 16. These events

filled with people observing this phenomenon and express-

greatly altered the societal landscape. Although the number

ing dissatisfaction. Yet there is not much information outof people staying at home has undoubtedly increased, we

there on the macro situation. As such, we report on thehave not seen that large a change in FLET’S traffic volume.

impact on traffic on IIJ’s FLET’S-based services as a bellwether of broadband services used mainly in the home.

3.2 About the Data
The traffic volume data is collected from the interface

COVID-19 began spreading in Japan in mid-February.

counters on routers that accommodate the fiber-optic

Remote work was still experimental at that point, but in lateand ADSL customers on IIJ’s personal and enterprise

February, companies like Dentsu and Shiseido embarked onbroadband services. We use data collected via Sampledlarge-scale remote work programs. Schools closed nation-

NetFlow to study the origin of traffic (sender organiza-

wide on March 2, and that same week, many companies

tions). Further details about the data are available in lastinitiated remote work, and as more and more people began

year’s Broadband Traffic Report*1.

Feb 17 - 23
Feb 24 - Mar 1
Mar 2 - 8
Mar 9 - 15

PPPoE download traffic0

Mar 9 - 15
Mar 16 - 22
Mar 23 - 29
Mar 30 - Apr 5

0

Apr 6 - 12

Apr 6 - 12
Apr 13 - 19
Apr 20 - 26

0

Apr 27 - May 3

Mon

Tue

Wed

Thu

Fri

Sat

Sun

Figure 1: FLET’s Traffic
Download: Feb 17 – Mar 15 (top), Mar 16 – Apr 12 (middle), Apr 13 – May 10 (bottom)*1

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Kenjiro Cho, Broadband Traffic Report: Moderate Growth in Traffic Volume Ongoing, Internet Infrastructure Review, Vol.44. pp4-9, November 2019.

© Internet Initiative Japan Inc.

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3. Focused Research (2)3.3 Traffic Condition

final week from the previous subplot for comparison. The

IIJ’s FLET’S services include IPv6 IPoE in addition to conven-holidays in this period are February 24 (Mon), March 20

tional PPPoE. IIJ’s IPv6 IPoE service uses Internet Multifeed(Fri), April 29 (Wed), May 4 (Mon), May 5 (Tue), and May 6

Co.’s transix service, and the traffic does not pass directly(Wed), and the traffic patterns on these days do differ fromthrough IIJ’s network. The volume of traffic here is currently

other weekdays.

around 20% of that on PPPoE. Congestion on network termination equipment has become a problem with PPPoE in

Downloads usually peak in the evening and fall off sharply

the past few years, and an increasing number of ISPs areafter midnight, with the lowest point coming in the earlyrecently recommending the use of IPoE.

morning. Daytime traffic is high on weekends/holidays.
Upload traffic is almost an order of magnitude smaller thandownload traffic, and there are no clear peaks.

3.3.1 FLET’S Traffic (PPPoE)
Figures 1 and 2 overlay IIJ’s total FLET’S traffic week byweek. This is PPPoE traffic and does not include IPv6 IPoE.

First, we look at download traffic in Figure 1. Comparing the

Figure 1 shows download and Figure 2 upload traffic.

two weeks represented by the red and orange series withthose represented by the aqua and blue series (i.e., before

The chart covers 12 weeks from the week of February 17,

and after March 2) in the top subplot shows that weekday

broken into three four-week subplots. The middle and bot-download traffic increased after March 2. Volumes were still

tom subplots contain five weeks of data as they include thea bit lower than on ordinary weekends. The peak values

Feb 17 - 23
Feb 24 - Mar 1
Mar 2 - 8
Mar 9 - 15

PPPoE upload traffic0

Mar 9 - 15
Mar 16 - 22
Mar 23 - 29
Mar 30 - Apr 5
Apr 6 - 12

0

Apr 6 - 12
Apr 13 - 19
Apr 20 - 26
Apr 27 - May 3

0

May 4 - 10

Mon

Tue

Wed

Thu

Fri

Sat

Sun

Figure 2: FLET’s Traffic
Upload: Feb 17 – Mar 15 (top), Mar 16 – Apr 12 (middle), Apr 13 – May 10 (bottom)© Internet Initiative Japan Inc.

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also increased just slightly. Not much changes in the middle

together. The dip around lunchtime is probably due to a lull

subplot, but the bottom subplot shows that weekday day-in video conferencing. Through mid-March, upload traffic

time traffic began increasing again in April. The increase in

only increased on weekdays, but thereafter evening andtraffic from early in the morning on March 11 (Wed) is likely

weekend/holiday traffic also rose. We think this is probably

due to the release of the popular video game Call of Duty:

due to an increase in video conferencing for private gather-

Warzone. Microsoft released a monthly update on the sameings, like afterwork drinks, as people became accustomedday, and this also probably contributed.

to the tools. The upload peak value, however, is only about
1/7th the download peak value, so upload traffic certainly

Next, we look at upload traffic in Figure 2. The top subplot

did not rise as much as download traffic.

shows that daytime traffic on weekdays rose slightly throughmid-March, but the increase eased off in the evenings, so it

To determine whether the increase in weekday daytime

is probably related to video conferencing and other remotetraffic was due to specific services, we also looked atwork applications. The middle and bottom subplots show

Sampled NetFlow data. A comparison of the Tokyo areaa progressive rise in weekday daytimes from April, likely adata for February 26 (Wed) and March 4 (Wed) shows anreflection of remote work arrangements gradually coming

overall 1.19-fold increase in download volume. By senderFeb 17 - 23
Feb 24 - Mar 1
Mar 2 - 8
Mar 9 - 15

IPoE download traffic0

Mar 9 - 15
Mar 16 - 22
Mar 23 - 29
Mar 30 - Apr 5

0

Apr 6 - 12

Apr 6 - 12
Apr 13 - 19
Apr 20 - 26
Apr 27 - May 3

0

May 4 - 10

Mon

Tue

Wed

Thu

Fri

Sat

Figure 3: IPv6 IPoE traffic
Download: Feb 17 – Mar 15 (top), Mar 16 – Apr 12 (middle), Apr 13 – May 10 (bottom)

20© Internet Initiative Japan Inc.

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3. Focused Research (2)organization (AS), the data show a decent increase in the

1.32x, and Microsoft 2.40x. This points to growth in full-

proportion of traffic from CDN operators, with the break-length video content, such as movies, and content tied todown among major content providers remaining largely thebusiness applications.

same. Specifically, the figures were Google 1.16x, Amazon
1.16x, Netflix 1.17x, Facebook 1.10x, and Microsoft

3.3.2 IPv6 IPoE Traffic

1.23x. So this was overall growth that was roughly equiv-

The reason PPPoE peak traffic is not rising could be thatalent across different sources of popular content, with no

the FLET’S network is congested, so here we look at IPv6

particular service being a clear standout.

IPoE, which should have ample capacity. Figures 3 and 4
plot IPv6 IPoE traffic volume. The download chart certainly

To examine the changes that followed, we now compare

shows the peaks rising, by a few percent in the top subplot,

February 26 (Wed) and April 22 (Wed). Overall download

barely at all in the middle subplot, and then again by a few

volume was up 1.20 fold, only a slight increase over March

percent in the bottom subplot. And compared with PPPoE,4, but the breakdown among major content providers shifted

weekday daytime traffic is lower relative to its peak. The

a little. Specifically, Google was unchanged at 1.16x, while

increase in weekday daytime upload traffic is also smaller

Amazon had 1.63x, Apple 1.00x, Netflix 1.36x, Facebook

than for PPPoE.

Feb 17 - 23
Feb 24 - Mar 1
Mar 2 - 8
Mar 9 - 15

IPoE upload traffic0

Mar 9 - 15
Mar 16 - 22
Mar 23 - 29
Mar 30 - Apr 5
Apr 6 - 12

0

Apr 6 - 12
Apr 13 - 19
Apr 20 - 26
Apr 27 - May 3

0

May 4 - 10

Mon

Tue

Wed

Thu

Fri

Sat

Sun

Figure 4: IPv6 IPoE traffic
Upload: Feb 17 – Mar 15 (top), Mar 16 – Apr 12 (middle), Apr 13 – May 10 (bottom)© Internet Initiative Japan Inc.

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3.4 Discussion

peaks should be rising where there is ample capacity, but

We were only able to take observations from IIJ services on

we did not observe any such differences over our observa-

this occasion, which tells us nothing about trends at othertional range.

companies. In mid-April, however, NTT East*2, NTT West*3,
and NTT Communications*4 released data on FLET’S traf-

IPoE peak traffic is increasing, but IPoE traffic depends on thefic volumes. Figure 5 plots the changes in weekday traffic

availability of content over IPv6, so the content breakdown

based on IIJ’s PPPoE data in the same manner as the graphs

differs from that for PPPoE and is not directly compara-published by the NTT companies. The plot shows average

ble. Also, the number of PPPoE contracts has hit a ceiling,

download (DL) and upload (UL) traffic for the weeks ofwhereas the ongoing shift to IPoE to avoid the congestion on

February 25 and April 20. It almost matches the observations

PPPoE means that IPoE contract numbers are also growing. Inof the NTT companies, so we think the same trends basicallyoverall terms, while the growth in IPoE download peak levels

held for FLET’S-based broadband services. We also think theseems to indicate that PPPoE is running out of capacity, thesituation on non-FLET’S networks with sufficient available

potential room for an increase in PPPoE peaks is probably

bandwidth is close to what we observe for our IPoE traffic.

smaller than the amount by which IPoE has increased.

From a macro view, weekday daytime traffic clearly in-Some changes are apparent in March and April too. In

creased after March 2. On weekdays, daily upload traffic

March, it looks like overall Internet usage increased as thewas up about 6% and download traffic about 15%. A 15%

number of people at home during the daytime on week-increase in daily downloads is about the same as the differ-days increased. Then in April, it looks like traffic related toence between weekdays and weekends, but another way

movie streaming and remote work increased as users got

to look at it is that an increase that would normally taketheir systems set up properly and became accustomed to

six months happened in a single day. But the peak values

the tools. As a characteristic effect of remote work, thedid not rise much, so from an ISP perspective, the former

increase in weekday daytime upload traffic is probably dueinterpretation makes sense. The reason the peaks did notmainly to video conferencing. But the volume is not all thatrise much may be due to capacity shortages on the FLET’S

large through the latter half of March, likely because the

network’s PPPoE network termination equipment. There

number of people video conferencing from home was still

may also be congestion at FLET’S network optical splitters

limited. Working efficiently when remoting in requires notor on consumer devices and wiring in apartment buildings.

only a decent home network setup and equipment, includ-

But such problems arise at the individual device level, so theing a PC, but also some level of experience. Companies

traffic

Feb 25-28 DL
Feb 25-28 UL
Apr 20-24 DL
Apr 20-24 UL

0

0

6

12

18

Figure 5: Average Weekday Traffic by Time of Day: February vs. April

22*2

NTT East, “NTT East’s efforts in response to COVID-19” (https://www.ntt-east.co.jp/aboutus/COVID-19.html#traffic, in Japanese).

*3

NTT West, “NTT West: Download traffic across all areas” (https://www.ntt.co.jp/topics/important/covid19_west.html, in Japanese).

*4

NTT Communications, “Internet traffic time series data” (https://www.ntt.com/about-us/covid-19/traffic/, in Japanese).

© Internet Initiative Japan Inc.

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3. Focused Research (2)were apparently experiencing problems on their end, in-Video overwhelms other types of content in terms of sheer

cluding a shortage of VPN licenses and bandwidth. And

volume, however, so usage trends for non-video content

many people were probably not fully set up for video con-are not really evident from the traffic observations because

ferencing when initially trying it out. The breakdown invideo streaming dominates download traffic and video con-

growth by operator shows a uniform rise in traffic from theferencing dominates upload traffic. There are limits to what

major content providers in March, followed by growth for

traffic alone can tell us about trends in Internet usage.

movie content providers and providers of remote work-re-

3.5 Conclusion

lated services in April.

The spread of COVID-19 has fueled a rapid shift toward
It is also clear that traffic falls when the weather is good andremote work. This has revealed problems with individual

rises when it is bad. People are thought to have relaxed andcommunication links and services, yet on a macro level, al-thus ventured out more amid favorable weather over thethough weekday daytime traffic has increased, it has recently

March 20–22 (Fri–Sun) long weekend, and as if to back thissettled at levels within the bounds of existing capacity.

up, traffic was low over that period. Eastern Japan and the
Tohoku region had stormy weather on April 18 (Sat), andRemote work and remote education were rolled out on atraffic increased on this day. Traffic was also on the highhuge scale from March. Until now, remote work had been anside in Kanto on April 13 and 20, perhaps because theseexperimental affair carried out by a select few, but we areconsecutive Mondays were both rainy.

now finding out whether everyone can do it at once. And
although the quality of Internet-based video conferencing,

Growth in broadband traffic was actually accelerating evenremote classes, video streaming, and the like is currently

before COVID-19 spread. Factors potentially behind this in-

sufficient when only some people are engaged, it will takeclude households becoming better equipped to stream video

years to build systems that can cope with large numbers ofas people replaced old PCs ahead of the Windows 7 end-

people all at once. Present circumstances have made clear

of-life and Japan’s consumption tax hike, the progressivethat society as a whole depends on online systems whenintroduction of remote work arrangements as part of work-

push comes to shove. Our hope is that this will provide astyle reforms and efforts to cope with the Olympics, andstrong impetus for reaffirming the importance of developing

increasing interest in video streaming fueled by expectations

Internet infrastructure.

for online streaming of the Olympics and TV broadcasts, 5G
mobile services, and the like.

Kenjiro Cho
Research Director, Research Laboratory, IIJ Innovation Institute Inc.

© Internet Initiative Japan Inc.

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