---
title: "25-advanced-topics"
aliases: 
tags: 
- cosc203
- lecture
---

# Datacenter networks
- 10's to 100's of thousands of hosts, often closely coupled, in close proximity
	- e-business :(e.g., amazon)
	- content servers: youtube etc
	- search engines, data mining (e.g., google)
- challenges
	- multiple applications, each server many clients
	- reliability
	- managing/balancing load
	- procesing, networking, data bottlenecks


network elements
- server racks, 20-40 server blades: host
- Top of Rack (TOR) switch
- Tier 2 switches: connect to ~16 TORS below
- tier 1 switches connect to ~16 T-2s below
- border routers: connections outside
- ![](https://i.imgur.com/kFOrQ97.png)

- multipath communcation
	- rich interconnecitions so many routes
	- increased throughput
	- increased reliability through redundancy

application-layer routing
- load balancer: app-layer routing
- recieves

# Software Defined networks