Virtp4 notes

be based on p4 Of the switch of VirtP4 Hard virtualization

Hard Virtualization of P4-based switches with VirtP4

significance

VirtP4, A conceptual framework , be based on p4 Hard virtualization of switch programs . Compared to the existing solution , No need to access the switch source code ( Whether for merge or custom compilation ). therefore , While providing near line rate performance for virtual switch instances , We retain the intellectual property rights of the switch program .

Challenge

Problems in operating system virtualization , Such as resource mapping and isolation

How to decouple virtual switch instances from virtualization boxes

How to guide frame input and output to the virtual switch instance

programme

According to the specification NetFPGA The reference design constructs VirtP4, Restructure its architecture to support p4 Parallel execution of switch instances .

Two VirtP4 modular :Input P4 Interface (IPI) and Output P4 Interface (OPI), They are responsible for forwarding frames from the virtual switch instance .

The former is responsible for dispatching the incoming data frames to the correct virtual switch instance .VirtP4 Use 32 position VLAN Mark (802.1Q) And one hosted in the controller match+ Action table to determine which switch instance must receive a given data frame . If a data frame contains a label not found in the table , The frame will be silently discarded .

The last block (OPI) Responsible for sending data frames to the correct physical address ( Output ) port . The module does not discard any frames .

stay VirtP4 in , You can write and compile switch code independently ( This means that you can retain ownership of your own code ).

Open questions

IPI/IPO Module query match+ The action table is hard coded .

This means that for the VLAN Marking scheme ( Or tag configuration populated in the table ) Your changes need to rebuild the entire project ( And burn it all over again FPGA plate ). We are studying FPGA Burn the part of the board again , In order to make VLAN The hot plug of tags and virtual switch instances can be rewritten , Without recompiling the whole project .

summary

VirtP4 Is based on p4 Conceptual solution and proof of concept implementation of hard virtualization of switch .