---
# System prepended metadata

title: '<center><i class="fa fa-edit"></i> Network Fundamentals: Routing Basics </center>'
tags: [Internship]

---

# <center><i class="fa fa-edit"></i> Network Fundamentals: Routing Basics </center>
###### tags: `Internship`
:::info
**Goal:**
To gain a basic understanding of the components behind network technologies. Focus on vocabulary and systems overview.
- [x] Routing Basics

**Resources:**
[Juniper Online Learning Modules](https://learningportal.juniper.net/juniper/user_activity_info.aspx?id=769)
[Pre-Internship Notes by Jessica Chen](https://hackmd.io/@j-chen/SyfRATOmD)
[Daily Report by Lin Yen-Ting](https://hackmd.io/@8KbRc796SnuYA2Dvsvk_BA/SJU_CawIL)
:::
## Module 3: Routing Basics

### Layer 2 and Layer 3 Addressing
- Layer 2 
    - Layer 2 address burned in by manufaturer
    - Collision domain: bridges and switches isolate traffic into separate domains based on the Layer 2 addresses in each frame
- Layer 3
    -  each NIC has a Layer 3 address assigned by the network administrator(specify the network number to all network devices -> introduces order) 
    -  Broadcast domain: all PC connected to the Ethernet switch that can be reached by sending a frame addressed to the broadcast MAC address
        -  Each devices has same network portion of their Layer 3 address and unique host number
![](https://i.imgur.com/EHKEdy9.png)
### Address Resolution (How do devices communicate using both Layer 3 and Layer 2 Addresses?)
- Sender PC detemines whether the destination PC resides on the same Layer 3 network or broadcast domain by comparing network numbers
    - will use a router if not in same domain
- Sender PC determines Layer 2 address by broadcasting a request in the broadcast domain 
    - All devices receive the broadcast but only the right PC will respond. 
- Both PCs can now communicate using unicast Layer 2 frames
- Address Resolution (Known as Address Resolution Protocol, or ARP, for TCP/IP based nteworks): process of using Layer 3 addresses to determine Layer 2 addresses 
    - ARP maps an IP address, which is a Layer 3 address to a Layer 2 address. Other known TCP/IP protocols use other protocols to resolve addresses
### Routers and Routing 
- Routers: Allows communication between broadcast domains. Each broadcast domain a becomes the single, separate network
![](https://i.imgur.com/GJlOvAK.png)
- Routing Protocols
    - Routing Information Protocol (RIP)
    - Open Shortest Path First (OSPF)
- Routing Table: Includes all possible destination network numbers and how to reach them
- Next-hop Address: Indicates that the destination network is directly connected to the router OR provides the address of another router on the directly connected network
- Problem: If router receives a packet destined for a network not in this routing table
- Solutions:
    - Drop the packet and gives error message to the sending PC
    - Avoid the situation
        - Network admins figure out with the default route (like an if-else statement)
![](https://i.imgur.com/xzu0AjH.png)
- Fiber Distributed Data Interface(FDDI): standard for data transmission on fiber optic lines; can extend in range up to 200 kilometers or 124 miles. 
    - Frame format is different that that of Ethernet
- Devices and Layers
![](https://i.imgur.com/2mRvxhs.png)
:::success
### Module 3 Summary
![](https://i.imgur.com/r1OmYUh.png)
![](https://i.imgur.com/echDNvZ.png)
![](https://i.imgur.com/bYsIgu5.png)
![](https://i.imgur.com/VoWjaBF.png)
![](https://i.imgur.com/ZEhvV4p.png)
![](https://i.imgur.com/1g0e7Ve.png)
![](https://i.imgur.com/vEuZHDK.png)
![](https://i.imgur.com/Ih2yJmW.png)
:::