---
# System prepended metadata

title: 計算機網路計算題

---

# 計算機網路計算題
packet transmission delay: L(bits) / R(Mbps)

d(link length) / s(speed of light propagation delay)
![](https://hackmd.io/_uploads/HyqgsXEw3.png)
1*10^6(m) / 3*10^8(m/s) = 3.3*10^-2 

### What is the maximum number of connections that can be ongoing in the network at any one time?
![](https://hackmd.io/_uploads/rJvb3l8vn.png)
加起來 = 68
### sends packets of data 
![](https://hackmd.io/_uploads/BJRCng8D3.png)
### Packet delay: four sources
![](https://hackmd.io/_uploads/BkT-Te8D2.png)
![](https://hackmd.io/_uploads/H1LzTlIw3.png)
### Encapsulation: an end-end view
![](https://hackmd.io/_uploads/rynSaeIv3.png)
### ISO
![](https://hackmd.io/_uploads/rJk_axUP3.png)
![](https://hackmd.io/_uploads/BJaoagIDh.png)
### HTTP request message: general format
![](https://hackmd.io/_uploads/rJHkCgLvn.png)
### HTTP response status codes
![](https://hackmd.io/_uploads/S1I-RgUv2.png)
### DNS records
![](https://hackmd.io/_uploads/rJ2H0gUw3.png)
### Internet checksum
![](https://hackmd.io/_uploads/SJFeyZ8w2.png)
### Performance of rdt3.0 (stop-and-wait)
![](https://hackmd.io/_uploads/S15E1WIPn.png)
### rdt3.0: stop-and-wait operation
![](https://hackmd.io/_uploads/B1L8kZUD2.png)
### Pipelining: increased utilization
![](https://hackmd.io/_uploads/H1GF1bIPh.png)
### TCP round trip time, timeout
![](https://hackmd.io/_uploads/HJW01bUD3.png)
![](https://hackmd.io/_uploads/HyEJx-Iwn.png)
### TCP throughput 
![](https://hackmd.io/_uploads/SJWVe-Uw2.png)
### IP Datagram format
![](https://hackmd.io/_uploads/HkEjxb8v3.png)
### dotted-decimal IP address notation:
![](https://hackmd.io/_uploads/SJLhx-Iw3.png)
### IP addressing: CIDR
![](https://hackmd.io/_uploads/SkPybbIvh.png)
### IPv6 datagram format
![](https://hackmd.io/_uploads/rkGfb-Iv3.png)
### Graph abstraction: link costs
![](https://hackmd.io/_uploads/ryYKbbUD3.png)
### Dijkstra’s algorithm
![](https://hackmd.io/_uploads/By8nZ-8Dh.png)
![](https://hackmd.io/_uploads/BJd6-bLD2.png)
### Cyclic Redundancy Check (CRC)
![](https://hackmd.io/_uploads/BJ4imbUDh.png)
### Channel partitioning MAC protocols: TDMA
![](https://hackmd.io/_uploads/HJ2r4ZLvn.png)
### CSMA/CD efficiency
![](https://hackmd.io/_uploads/r1YtE-UD2.png)
### MAC addresses
![](https://hackmd.io/_uploads/rkds4-UP3.png)
![](https://hackmd.io/_uploads/HythV-Lw3.png)
### aloha
n = 2
p = 0.23
Np(1 - p)^2(N - 1) = 2 * 0.23 * (1 - 0.23)^2(2 - 1) = 0.27 or 27% efficiency.
### port number
![](https://hackmd.io/_uploads/HkitbtIvh.png)





