Why is broadband only 50 Mbps upstream at 1000 Mbps downstream? The rules were set in the era of telephone lines, and fiber optic fibers hadn't changed either

last week on a business trip and staying at a hotel, I wanted to watch the 4K original drive from my NAS at home tonight. The progress bar was stuck at 5MB/s. My first reaction was that my home router was out of air, so I tried restarting remotely, but it didn't help. I suspected the network cable had lost 100Mbps in negotiation, but when I checked the status page, I saw 1000M fully negotiated. After ten o'clock, I inexplicably opened the Telecom business hall app to check the package details: 1000 Mbps downlink, 50 Mbps uplink.

50 MB/s divided by 8 equals 6.25MB/s, and after deducting the overhead of TCP acknowledgment packets and tunnel encapsulation, it can actually run just over 5MB/s. In other words, this number is not a malfunction, but a ceiling. I spent ages fixing the problem, but it wasn't a problem at all. After

got home, I thought about it over and over, and the more I dug in, the more interesting it seemed: the 20-fold uplink and downlink difference wasn't decided by any operator; the rules were passed down from the telephone line era, and fiber optic is still in use. This article breaks down three layers of reasons.

first take a good look at the two broadband pipes in your home

Many people think broadband 100 Mbps is just one 1 gigabit tube, and both ends can run full. Actually, there are two tubes: one goes into the house (downward), the other goes out (upward), and the thickness is quite different. The ability of your router's WAN port to send out per second is determined by that thin tube.

want to see how thick your own tube is, there are three places to check: the service hall app's package detail page (the most accurate, which lists the contract rate); Work order text messages from the year of installation; Or just use a speed test tool to click the upload button—make sure to disable all home cloud storage syncing and cloud monitoring before testing, otherwise the test will show what's left after everything was stolen.

typical gear looks like this:

shows no pattern: the more expensive the package, the more aggressively the price rises, while the upside basically stalls. I once wrote an article how much broadband is enough for , but I left it unexplored—why did downloading triple when upgrading to gigabit but not moving up at all? This article will fill in the "why."

Telephone Line: Asymmetry is written in the name

My first broadband cable was an ADSL installed in 2004, with 8MB downlink and 512k uplink. At that time, I wondered why uploads were so slow, but later I learned that the four letters 'A' in ADSL stand for Asymmetric—Asymmetric — the asymmetric numeric user line. The name itself is mentioned; he never intended to be symmetrical to you.

the root of the asymmetry lies in the frequency band allocation of that telephone line. A single copper wire can operate at frequencies from 0 to 1.1MHz and is cut into three segments:

the bandwidth allocated to downlink is 8.6 times the width of the uplink band, so naturally the speed is much lower. Why cut it so much? Because in the early 2000s, operators understood "browsing the internet" as just browsing web pages and downloading things; users hardly needed to send data outward, and good bands naturally gave them downlinks. This consumer-oriented positioning of "download-first, upload a bit" has set the tone since the Copper Wire era.

telephone lines have long been phased out, but the rules they set still persist today.

fiber optic cables, asymmetry is actually written into international standards

I originally thought that after switching to fiber, upstream and downstream would be on equal footing — fiber capacity is so large. After checking the standards, I realized I was overthinking it.

here's a fun fact: although your incoming fiber is a double-core wire, it actually uses only one core. Uplink and downlink are distinguished by different wavelengths: downlink uses 1490nm for broadcast, uplink for 1310nm to send back. But the international standards set asymmetric speeds for these two directions: GPON (now used by the vast majority of households) has 2.488G downlink and 1.244G uplink, 2:1; with the next-generation XG-PON, 10G downstream and 2.5G upstream, it actually stretches to 4:1. There really is a symmetrical version called XGS-PON, where the 'S' stands for Symmetric. Both uplink and downlink are 10G—but this is mainly for enterprises, rarely for home use. the Tianyi Gateway 3.0 and 4.0 article discussed the differences between these two routes. If you want to switch to a 10-gigabit optical modem, you can check it out.

there's an even more heartbreaking layer: this thread isn't for you alone. The splitter in the community corridors can be at most 1:64, meaning 64 households share the same fiber. Downstream is broadcast mode, with data sent from the bureau, each claiming its own portion without delay; If you go up, you have to queue; 64 optical modems take turns speaking in the time slices. So even if the PON port's physical uplink is 1.244G, 64 merchants per cent, and the package limits it to 50 Mbps, that's the number you see in the service center app.

operators' calculation: Uplink is just for price tags

After looking at the technical layer, you might ask: XGS-PON can already have symmetric 10G, so why won't JiaKuan give me it? This is the third layer—not because it's technically impossible, but because the product positioning is unwilling to provide it.

home broadband is priced as "consumer-oriented": a few hundred yuan a year, assuming you just watch videos and get the rest of the video. Symmetrical bandwidth is placed on another shelf called a business dedicated line: Shanghai Telecom's 100M/500M symmetrical dedicated line is priced at 6,880 yuan per year, about ten times the home bandwidth. Upward is the differentiation point used to mark the price and sell. Why is

upward movement so valuable? Here's a note: most of what you download comes from the operator's own CDN servers (video sites are deployed at full cost in various data centers), and the traffic circulates within the network, making it low-cost; The destination you upload is often on another operator's network, and you need to use inter-network interconnection settlement, which is the expensive bandwidth. For the same megabyte, the cost of downloading and uploading is different.

there's also an anti-abuse consideration: if the upstream really gets high, someone will use Jiakuan to set up websites, run sites, or use it as a small data center to sell traffic. So Jiabroad not only has a small uplink but also defaults to blocking ports 80 and 443— mentioned in the article about checking public IPs, people who want to run web services at home are blocked by these two ports. If you're away connect home to NAS via VPN, speeds hit the 5MB/s ceiling—the root is here.

uplink is insufficient, and all the stuck users are "sending outward" work

while downstream users are actually not enough; those truly pushed into the corner by bandwidth are basically upstream users. I made a record of my family's eating and eating on the road:

the last two scenarios I for home office network configuration elaborated in that article, with the core sentence being one thing: those rushing to go are the hidden big players. Even more ruthless, the logic for charging cloud drive services is the same for uplink services—the free version of Nut Cloud only allows 1GB per month, and the price is set to meet users' pain points for uplink needs.

So when it really comes to competition, your optimization direction isn't downward, but that narrow pipe. Why can't Feiniu's remote access get faster? I previously discussed it in the of FN Connect. The free relay version is slow, but even if it really connects point-to-point direct connections, the speed still hits the 50 Mbps ceiling. No matter how many pipelines you replace, the main gate in the building is only that thick.

want to go upward, there are only a few paths

Now that you know the reason, the method is actually easier to choose. Sorted by spending money:

First, the uplink acceleration package. some city operators are selling it. For example, Beijing Unicom adds 100M uphill for about 30 yuan a month, totaling 360 yuan per year, roughly the price of buying another home broad bill. The cost-performance ratio isn't great, but the changes are minimal. Just call customer service and you'll get it. First, check if the product is available in your city.

second, to add another broadband. I do this: main broadband and telecom gigabit pipes daily, plus a mobile secondary line dedicated to downloading, monitoring, and backup—all the dirty tasks sent upward. The two lines go their own way without disturbing each other. I wrote about this setup in the of dual broadband. Cheaper than the speedpack, but the trade-off is the hassle of dual WAN.

third, business dedicated lines. symmetrical uplink and downlink links, fixed IP, starting at over 6,000 per year. This is for the company; unless you really use a NAS as a production tool at home, it's not worth it.

fourth, the cost-free approach: staggering peak times and reducing demand. backup tasks are moved to the early morning hours, while daytime upbound tasks are reserved for meetings; Remote viewing has been changed to watching at home (LAN does not take up the uplink); For a one-time big move, I decided to physically move the old Synology machine directly to my mom's house, set it up, and then bring it back, which is much faster than online uploading 206GB. Speed testing is one thing, but the correct posture for speed testing check out another article. Don't always focus on benchmarking scores when using the internet daily.

Here's the order to wrap up: first open the business hall app and copy down the upward number for your meal, then check the table on it to see if your usual work is going up. If not, congratulations on saving your mind, and pick your meal from top to bottom based on how much you spend. The issue of upstream and downstream imbalance can't be changed in the short term; the only thing that can be changed is your own internet habits.