莫斯科大學的學生自己在宿舍架設宿舍網路的歷史故事 (2002~2013)

Lobster Daily 看到「Moscow state university network built by students」這篇,不過 Hacker News 上的討論多一點:「“Illegal” Moscow state university network built by students (2002-2013) (medium.com/pv.safronov)」。

莫斯科大學宿舍網路的故事,發生在 2002 年到 2013 年之間:

They had built a network on their own, which provided students Internet connection from 2002 till 2013 (when the administration effectively legalized this network).

算是老人懷舊的故事,不過看起來作者留下了大量的照片看起來就更有趣了...

查了一下資料,交大應該是 1993 年 1992 年就開始有宿舍網路了 (可能更早?),而且是校方用同軸電纜 (Coaxial cable) 拉的,後來經過更新也換到雙絞線了 (UTP,Twisted pair),現在應該是 1Gbps 的頻寬,不過不知道建築物之間是怎麼放的了。(大概還是光纖,依照集縮比應該是跑 10Gbps 的協定,S 系列的那幾個可能距離都太短,大概是 L 的吧,不知道是幾對...)

首先這是個橫跨整個主建築物的網路建制,分成五個大區塊:

Google Maps 拉一下距離,光是兩端的直線距離就快要 0.5km 了,應該沒找錯建築物,看起來是這棟沒錯...

從作者提供的圖片也可以看出來建築物本身超大:

回到網路的部份,本來是用 10Mbps 的 Hub 接 (算是 2002 年比較好取得的網路設備?),但因為是 Hub 所以頻寬使用率不高 (Collision domain 的效率下降),換成 Switch 後降低了很多不必要的流量:

In the beginning, there were only 10 Mbps hubs available. They were extremely slow because the packet arriving at one port was mirrored to all other ports, flooding the network with unnecessary traffic. Later they were replaced by L2 switches, that are smart enough to choose the destination port for the packet.

但宿舍網路是有競爭對手的,兩邊常常破壞對方 XDDD

Having two competing networks was a cherry on the top of it. They were cutting each other’s cables, executing DDoS attacks, stealing equipment, etc.

然後是拉光纖對接幾個主要的區塊,以上面剛剛拉出來的數字來看,應該是因為雙絞線 (UTP,Twisted pair) 的 100 公尺長度限制,所以這部份必須透過光纖:

To connect this router to the other parts of the network, we laid fiber cables through secret passages in the walls, ceilings, floors, and ventilation shafts.

然後用 Switch 再拉到每個房間 (所謂的 Last mile):

然後外部就沒在怕你的拉:

還包括了把 UTP 的八芯線分開用的方法,這邊提到了 100Mbps 應該是升級上去了:

Most of the time, we managed to reduce the number of cables coming out of the window down to ~15. We could do this because of a simple trick: the regular ethernet cable (Cat 5e) has 8 wires. And to transmit 100 Mbps, you need just 4 of them. All 8 wires are required only for a 1 Gbps connection. So using a single cable, you can connect 2 clients who live close to each other. We always tried to do that if possible because the hole can’t fit so many cables.

往後拉一點的樣子:

後面講到很多故事以及常見的 trouble shooting 問題,現在的網路設備能支援的架構好太多,應該都有比較好的解法了...

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