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tags: class note, nccu
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# 新世代資料中心的發展趨勢與自動化管理

[](https://hackmd.io/oPfkjpXkS42CasNqznCUCA)

[TOC]

## Internet and Cisco
## ARPANET (the progenitor of the internet)
## Cisco
* Cisco System was founded on Dec. 10, 1984 by Sandy Lerner and Bosack
* logo 就是舊金山大橋
* Slogan: **Bridge to Possible**
* developed a groundbreaking new connectivity device called a router

## Network Evolution
### Campus network and Datacenter network
- 網路分為兩個世界(網路架構):
- Campus network
- 三層式架構
- Core Layer (計中) -> Distribution Layer (Building) -> Access Layer (Level, AP, port)
- Datacenter network
- Server, Storage, Router
- Two-tier: spines and leaves
- Fully Connected Bipartite Graph
- 要加大頻寬的話 -> 加 Spines
- 增加 port 數 -> 加 Leaves
- 現今稱私有雲

* Traffic flow
* North and South (access -> distribution -> core)
* West and East (Leaves to Leaves)
* Campus Network 多需要 PoE (AP, Camera), Datacenter 瓦數不足

### Ethernet Layer 2 Fundametal
#### Switch: self-learning
* If recive dest ffffffff the client can only recive
* Hub
* Receive packet, copy and pass to others nodes
* Switch will record MAC address (source and dest) of each packet
* Record port and MAC address
* (DON'T know where to pass) pass to all others nodes
* Record the port of the dest MAC

| MAC addr | interface | TTL |
| -------- | -------- | -------- |
| A | 1 | 60 |
| A' | 4 | 60 |

### VLAN and VXLAN
* Cloud 快速部署的基礎
#### VLAN

- 48 Ports Switch -> 4 mini 12 Ports Switch
- Add VLAN ID (12bits) to packet (In Switch)
- The same VLAN ID could receive the packet.
- 切出不同區域網路 with only 1 switch
- How to add tag:
- PC don't know which VLAN it belongs to
- the switch will attach/detach the VLAN ID
- Adding Trunks Port in high level switch to decide which packet could pass

- In Campus Network and Datacenter Network
- Ref. IEEE 802.1q VLAN trunk protocol
- 缺點：
- 12個bit，4096不夠用
- 網路第二層，廣播（只要有廣播都需要處理？？，收到 broadcast packet switch 會傳給所有 node 全部 node 需接受該封包）
> BUM: broadcast unicast multicast
- multi-cast(群播) -> 也會佔頻寬
- Broadcast 受到阻斷不能在廣域網路使用
#### VXLAN
- Layer 3 IP Layer
- 不一定要基於 VLAN，只要一般封包即可 （避免 broadcast 封包，因此透過 IP Layer 封裝讓對方可以接收，對方第三層拆封包後）
- like VPN 做法（替換 IP address）
分配：
- 封裝相關工作：leaf、border leaf

#### Data Center "Fabric" Journey
- Spanning-Tree:
- 避免 Broaadcast Storm 讓特定線路待定
- VPC (virtual port channel ~~Virtual Private Cloud~~)
- 將多個不同的線路虛擬成同一條網外接，以增加頻寬
- VXLAN Flood&Leam
- 第三層網路，所以可以完全連接
- VXLAN BGP EVPN
- Depart control plane and data plane

#### Datacenter network requirement
- Increased Bandwidth, Rich Features
- Multicloud Orchestration
- Application Performance
- Faster Deployment
- Highly Skilled People

## Software Defined Network (SDN)

- 透過程式碼達到自動化快速網路建設，並且可以簡化建設流程

- SDN 為概念（做法）無 IEEE 定義非 protocol 各公司實作不同
- automation/simplification
- savings
- not protocol
- not single industry standard
- an approach

區分
network controller and network state, structure 並可以動態調整

SDN is
- …a new approach at network transformation
reserved. CiscoPublic
- …impacting the networking industry
- …providing new methods to interact with
equipment/services via controllers, APIs
- …enabling high-scale, rapid network and
service provisioning/management
- …generating a LOT of attention
- …providing a catalyst for traditional
Route/Switch engineers to branch-out

SDN is not
- …an easy button
- …an end-state
- …narrowly defined
- …meaning the death of network
engineers
- …a mandate for all network engineers to
become programmers
- …a new attempt at network evolution

- Dynamically apply state and control to network infrastructure using globally aware software controls
- Decoupled control and data planes and centralised intelligence
- Abstraction of underlying network infrastructure

## overlays and underlays

### Application Centric Infrastructure (ACI)
以應用為中心的架構
- NEXUS 9000 Fabric
- Application centric policy
- Controller

It is a programmable physical and overlay fabric with a single point of management configurable via API, CLI or GUI.

### ACI: How difficult is it to bring it up?

## How does Ansible work?
* Linux host with a Python and the Ansible installed
* Support transport to remote hosts
* Typically SSH but could use an API
* Ansible Components
* Ansible configuration file
* Inventory files
* Ansible modules
* Playbooks