1. Co-operative Server Pool for Hotspot Rescue Service
Weibin Zhao
Henning Schulzrinne
1/13/2019

2. Outline Problem space for hotspot Alleviating hotspot
Co-operative server pool
Previous experience
1/13/2019

3. Problem space for hotspot
Place
network
server
Object
Small web
Large file
Stored media
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4. Alleviating hotspot Load Balancing Hotspot Rescue Hotspot Avoidance
Co-operative
Server Pool
Smart Client
P2P
Server Selection
Caching
Service
Migration
Client
Redirection
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5. Co-operative server pool (CSP)
 MASH (mutual aid society for hotspots)
Form server pool (*)
Server pool architecture (*)
Rescue vs. local service
Monitor servers in the pool (*)
Predict and detect hotspot
Select candidate for migration (*)
Client re-direction (*)
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6. Form server pool Membership service Overlap server pool
Static configuration
DHCP
Dynamic membership via advertisement
Overlap server pool
Multiple scopes
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7. Server pool architecture
Full mesh
Autonomous, peer to peer
Simple, reliable
Scalability: O(10)
Other topology
Spanning tree
Two-level: tree + mesh
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8. Monitor server in the pool
What to do?
Aliveness
Load information
How?
Direct: for neighbors in mesh/tree
Indirect: for tree
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9. Migration Select candidate Available resources at candidate
Network path to candidate
Migration cost
Potential performance gains
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10. Client re-direction Mechanisms Evaluation Refer (*) Tunnel DNS
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11. Previous experience mSLP Remote SLP discovery
Mesh-enhanced service location protocol
Remote SLP discovery
DNS SRV
Gateway selection for IP telephony
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12. mSLP Full mesh server pool Multi-scope server pool Membership service
Data exchange
Update forwarding
Initial data exchange
Multi-scope server pool
Use scopes for scalability
Flexible for different purposes
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13. Full-mesh multi-scope server pool
Server1 (E,B)
(E)
(B)
Server2 (B,L)
(L)
Server3 (L,E)
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14. Remote SLP discovery Three configurations DNS SRV Small: only SAs
Medium: DAs in one scope
Large: DAs in multiple scopes
DNS SRV
All servers should be equivalent
Gateway DAs for small/large configurations
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15. Gateway DAs SA1 SA2 DA1 (Sa) SA3 SA4 DA2 (Sb) Gateway DA Gateway DA
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16. Gateway selection for IP telephony
Service template
Total capacity, remaining capacity, prefix list (destination), cost list, ASR (answer-seizure ratio) list
Location server & gateways
Gateway: register
Location server: directory service
Direct client call to gateway
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17. Gateway selection Gateway1 Location Server Incoming call Gateway2
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18. Big Picture Where to put the intelligence In front of servers
With server
@ client
In the middle: directory server
Server1
Directory
Client
Server2
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