1. Reconciling Zero-conf with Efficiency in Enterprises
Changhoon Kim and Jennifer Rexford Princeton University
1. State of the Art and Motivation
Enterprise networks comprised of Ethernet-based IP subnets interconnected by routers
Recent challenges
Very large and highly populated Ethernet segments (e.g., campus-wide WLAN)
Wide deployment of light bridges (e.g., wireless APs)
Sometimes incapable of bridging, STP, VLAN, etc.
Increasing demand of mobility
Increasing complexity and inefficiency of IP address management (even with DHCP)
Need for MAC-based access control
Neither IP routing nor Ethernet bridging suffices
Mechanisms
Features
Ethernet Bridging
IP Routing
Ease of Configuration
Good
Poor
Mobility
Addressing Optimality
Path Optimality
Load Distribution
Tolerance to Loop
Convergence Speed
IEEE 802.1D
Ethernet Bridging
- Flat addressing
- Self-learning
- Flooding - STP C A
IP Routing
- Hierarchical addressing
- Shortest path routing
- Subnet configuration
- Host configuration E B D
Can’t we just take best parts of each?
2. Solution: SEIZE (Scalable and Efficient Zero-config Enterprise)
Addressing and packet format: IEEE 802 Ethernet
Mobility and minimal configuration via flat addressing
Backward compatibility (including VLAN support)
IP address provides external connectivity and application compatibility
Core connectivity dissemination: Link-state protocol
Efficient resource utilization via pair-wise shortest paths and load distribution
Scalability
Fast convergence
End-host information dissemination: Consistent hash
Scalability and stability via on-demand binding of host address and location
Resistant to high churn rate
O (1) look-up via link-state core
2.5 Delivery
to x
3.2 Optimized tunneling
directly from E to A y x C
1.1 Host discovery
or active registration
2.1 Traffic to x A
2.4 Tunneling to
egress node, A
1.2 Hashing
(H(x) = B)
2.3 Hash-based routing to the relay node, B
2.2 Hashing
(H(x) = B) E
Link-state core
Entire enterprise
- A large single IP subnet (e.g., /16)
3.1 Notifying <x, A> to E B
Network Node
(MAC addr. = A)
1.3 Storing <x, A> at B D A
End-host
(MAC addr. = x) x q p
Control flow
Unique and location-independent IP addresses that do NOT belong to a specific subnet
Data flow
3. Design Options
5. Prototyping and Evaluation
Packet delivery mode
Relayed or Direct
Packet delivery mechanics
Tunneling or Label swapping
Label swapping borrows src MAC field to contain dst MAC
End-host discovery
“Discover-from-data” or Active registration
ARP and DHCP
Broadcasting or CHash-based proxy resolution
Overloading DHCP for host discovery
Intelligent broadcasting
A sequence of unicasts along spanning tree
Native Prototype
Control plane
XORP OSPF daemon
Data plane
Click EtherSwitch elements with some SEIZE extensions
Overlay Prototype
Wide-area virtual enterprises
SIAS (SEIZE-In-A-Slice)
Another VINI instance
Data plane
IP-encapsulated Ethernet frames
Click EtherSwitch and IPRouter elements with SEIZE extensions
Evaluation
Modeling and analyzing host information caching behavior
Simulation with ns-click
Emulation on Emulab or PlanetLab
Intra-enterprise/campus traffic dumps (just headers) are welcome!
Click
XORP
IS-IS/OSPF
SEIZE
Switch
CHash Rings
HostInfo Store
LS msgs
Host info. query and registration msgs
Data frames
4. Further Applications
Load sensitive routing
E.g., Selective application of VLB (Valiant Load Balancing)
Service mobility
Relay node masks hand off
Src MAC-based reachability control
Path obfuscation or anonymization
Topology does not reveal actual data paths