CSE 124 Lecture Notes - Lecture 26: Collaborative Filtering, Data Center, Rakuten.Com
4 Jun 2018
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Overlay Networks For Routing
Underlying network
- Internet connectivity (IP routing)
App-Layer Overlay Example
- “Tree” constructed using application-layer sockets
- data flows along tree, NOT underlying network!
Why?
- Can improve reliability
- If link fails, it can take TIME for the Internet to recover!
- Disseminate data in a scalable way
- Avoids “censorship”
Idea:
- Every node in our system is part of the tree
- NO cycles
- Between ANY two points, there is exactly one path
Depending on how you “construct” your overlay networks, it might perform better or worse than
through the underlying network!
Key Concepts
Links stress - how often a packet “transits” a given link
Relative delay penalty (aka “Stretch”)
- Ratio of delay in OVERLAY vs UNDERLYING network
Ex:
Network cost A → F = 1
Overlay cost A → F = 4 + 2 + 2 = 8
Relative delay penalty A → F = 8/1
Cloud Computing
- elastic resources - can access various amounts of resources over time
- expand and “contract” resources
- PAY-per-use
- infrastructure on demand
- multi-tenancy
- multiple independent users
- security and resource “isolation”
- amortize the cost of the (shared) infrastructure
Cloud Service Models
- Software as a service (Saas)
- Provider “licenses” applications to users as a service
- Running in the cloud (hidden to the user!)
- Avoid costs of installation, maintenance, patches,etc.
Document Summary
Data flows along tree , not underlying network! If link fails, it can take time for the internet to recover! Every node in our system is part of the tree. Between any two points, there is exactly one path. Ratio of delay in overlay vs underlying network. Depending on how you construct your overlay networks, it might perform better or worse than through the underlying network! Links stress - how often a packet transits a given link. Overlay cost a f = 4 + 2 + 2 = 8. Elastic resources - can access various amounts of resources over time. Amortize the cost of the (shared) infrastructure. Provider licenses applications to users as a service. Running in the cloud (hidden to the user!) Provider offers raw computing, storage, and network. Avoid buying servers and estimating resource needs. No need to be compatible with the outside world .
