A Vision for Runtime Programmable Networks
https://dl.acm.org/doi/10.1145/3484266.3487377
How important high velocity is for improving the manageability and functionality of network
SOTA in network programming
With P4 and other programmable network frameworks, operators compile and reflash the data plane w/ new program
Much much faster than buying new hardware (make changes much quicker)
However, reflashing can cause downtime and packet loss
Want high up-time
Physical resources are often scarce
To avoid downtime, changes must be infrequent and operator driven
Benefits of velocity
Frequent upgrades to the data path
90% incidents happen during management operations
Network in production use are not static
New needs inevitably arise! (e.g., security responses)
Changes need to be coordinated across switches, NICs, servers
Applied to only part of the traffic at a time
FlexNet: live changes in seconds
Runtime network (re)programming end-to-end
No downtime, zero packet loss, consistency guarantees
Users can inject customizations to the network
Why FlexNet?
Ex: real-time security defense
Network devices swap defenses
Hot patching zero-day attacks in the network
Dynamic scaling based on attack patterns
Just-in-time network specialization
Common mode: basic network logic, low footprint
JIT specialization based on workloads and applications
Tenant-specific extensions
Tenants directly customize network logic
Incremental infrastructure upgrades
Coordinated changes at the NIC, switch, and the host
E.x. deploy new CC protocols for a slice (for a particular group of cloud tenants)
Possible? Why now?
Individual targets are becoming runtime programmable
P4 and NPL programmable switch ASICs
SoC and FPGA SmartNICs
Runtime programmability --> partial reconfigurations
Host kernel stacks
Host-kernel: runtime loading of eBPF programs, kernel loading be dynamically configurable
Ex: Runtime programmable switches (NSDI '22)
Add, remove, and modify match / action tables
Change packet header parsers
Reconfigure control flow
Runtime programmable networks
Need a way to program the entire network, and need new abstraction to map packet processing to individual components of this network --> whole network programming
Runtime reconfigurability, with incremental changes, minimally destructive to each of these individual components
Control plane, real-time network control: manage the network as apps move from one place to another place
Overall, FlexNet raises new challenges across the stack
FlexNet supports runtime deployment, migration, and scale-in, scale-out of applications
New abstractions --> hide the details that program components can migrate across the network
Programming a "fungible" datapath
Compiler: analyze programs, and automatically generate the distribution and migration plans
The end-to-end network provides a fungible datapath
A logical "whole-stack" device
Hiding details on vertical / horizontal distribution
Whole-network program compiled to the devices
Incorporating real-time changes
Infrastructure program provided by the network owner
Basic utilies, e.g., ACL, telemetry
Tenant extensions injected in real time
User-specific upgrades, e.g., DDoS, refined telemetry
Research questions: programming, compiling, and optimizing these runtime changes are all interesting questions to look like
Managing elastic network apps
Network management system requires a re-design
Today mgmt and control solutions are box centric and focus on individual devices, but FlexNet apps can migrate across the network (not fixed location)
Need solutions that are app-centric
New primitives are needed to name the apps, control the migration and replication without worrying about the device-level details
Supporting control operations with new data plane primitives
E.g. app / state replication
Summary
Non-programmable: vendors control network logic, changes happen in years
Compile-time programmable: operators control network logic, changes happen in weeks
Runtime programmable: Users control network logic, changes happen in seconds
A new modality of network programmability
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