The Design Space of Network Mobility

Transcription

1 The Design Space of Network Mobility

2 Key ideas Network Mobility Seamless Mobility Overview of implementations and challenges Geomorphic model New abstraction for the network stack Helps us discuss, understand the above

3 Why is network mobility important?

4 Why is network mobility important? Mobile devices make rapid network handoffs an issue Effective, efficient handoffs (handoffs still cause noticeable delays) New and emerging technologies require effective network mobility Internet built around static devices Identifier/locator conflation Any thoughts on other uses?

5 Related issue: Multihoming Simultaneous multihoming WiFi and cellular at the same time! Reliability, performance Less switching overheads Other applications: More reliable wired networks (several providers?) Look at multipath TCP

6 Related issue: 5G (Not actually discussed in the paper) One proposal: Dense network of small cells Highly efficient handovers become critical

7 Other related applications Data center migration Anycast Get content from one of many servers easily (better CDNs?) LANs that move around (e.g. on planes, buses) Cooperative downloads? Better support for seamless VoIP Cellular?

8 The geomorphic model

9 The geomorphic model Standard network model Geomorphic model

10 Layers in the geomorphic model

11 Why the geomorphic model?

12 Why the geomorphic model? Finer grained, more flexible categorization Allows us to talk about general networking concepts and principles without being tied to a specific technology Places no limits on the network technologies we can discuss Thoughts on this scheme?

13 Pattern 1: Dynamic Routing Mobility Change routes

14 Pattern 2: Session-location Mobility Change locations

15 DRM vs SLM

16 DRM vs SLM DRM: Higher storage, update costs Don't have to worry about malicious endpoints, but can we trust the middleboxes? SLM Requires end points to participate Incremental deployment? Malicious endpoints?

17 Non-hierarchical DRM: Ethernet

18 Non-hierarchical DRM: Ethernet Per-switch forwarding table Add unknown source MACs to the table as they come Unknown destination MACs: forward to everyone Flooding does not scale well to large, dynamic networks...

19 Non-hierarchical DRM: Ethernet Overlays

20 Non-hierarchical DRM: Ethernet Overlays Avoid flooding in several ways Switches can be told to inform requesting switches to invalidate stale links Pseudo-MAC addresses: rewrite every time No flooding = shorter paths Remove the no cycles requirement Used for some SDN systems (Portland...)

21 Hierarchical DRM: Mobile IPv4 and alternatives

22 Mobile IPv4 Key idea Goal: only a small number of routers actually know where devices are Normal links get all packets to Home address Tunnelling layer gets packets from HA device

23 MSM-IP Key Idea Put mobile host in a multicast group When the mobile host moves, add the new location to the multicast group and remove the old one Special tunneling layer to route multiicast messages Higher update costs (more routers to update) Lower path cost (don't rely on central home ddress)

24 Session Location Mobility Examples

25 Session-location mobility Most proposals experimental Identifier and locator in separate layers

26 Session-location mobility Identifier: IP address (or suffix) Hash of public key Locator Usually an IPv6 address (different from the above) Directories Add to DNS Use home agents A custom system (more flexible, but needs to be implemented)

27 Composition of both models

28 Alloy Analyzer Model arbitrary protocols and reason about them Demonstrates many theoretical ways mobility could be designed Demonstrate you can use both DRM and SLM

29 Mobile IPv6 No FA: the mobile device takes care of changing mobility instead Optimization: use HA for storing entries only, avoid routing all traffic through it

30 Security considerations? Who gets to decide what gets rerouted? Denial of service attacks? What about accidental misconfigurations? Is DRM really more secure for making configuration changes in the network? Other concerns?

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