What is network management?
Process of configuring network to achieve a variety of tasks.
What kind of problems can network misconfigurations lead to?
Why is configuration hard?
What does SDN provide to operators?
What should routers do?
What is SDN … in the most succinct way.
“Remove routing from Routers”
What is SDN, really?
2. Network Wide Control
What is the control and data plane?
Conventionally, Control + Data run on routers
in SDN, control runs in a centralized program and distributes the rules to the routers.
What are the advantages of SDN?
Separation of control plane means we can apply CS techniques from programming languages or software engineering to help us reason about the network.
What is the difference b/t the control plane and the data plane?
Routing Protocol compute paths (Control Plane) -> Forwarding Table Entries (Data Plan)
Why is separation of Control/Data planes a good thing?
What opportunities are provided by separating data and control?
What are the challenges of SDN?
Scalability: a control element may be responsible for hundreds to thousands of switches
Consistency: Ensuring different replicas see the same view of the network
Security/Robustness: network still functions after failure or is compromised.
What is network virtualization?
Abstraction of a physical network
Multiple logical networks on a shared physical substrate
Sort of like VM’s with the hypervisor. Each network think it’s view is the real view of the network but the underlying real network is hidden from it
Separation of logical and physical network.
What is traffic engineering?
Reconfiguring the network in response to changing traffic loads, to achieve some operational goal
Describe link weight tuning in Intradomain traffic engineering
Adjust link weights to redirect flow within the network to take the path you want it to take.
Some ways to set link weights are:
What are the three steps to traffic engineering?
Measuring - the topology and traffic
Model - pass that into a what-if model to figure out what changes to make
Control - make changes to link weights
What are the goals of interdomain traffic engineering?
What characterizes a datacenter?
+ amortization of cost
- security, resource isolation
What are the challenges of data center networking?
Why is the internet insecure?
What are the components of Security?
What is Control Plane Security?
Determine voracity of routing advertisements.
Session: protects point to point comms b/t routers
Path: protects AS path
Origin: protects origin AS in AS path, guaranteeing origin AS that advertises prefix is the owner of that prefix
What’s the ‘TTL Hack’ defense?
Set the TTL to 255 and then the receiver drops anything that has a TTL of < 254. Generally eBGP communication is only a single hop away and most attackers are remote.