One Protocol Many Layers A Recursive Network Architecture

Outline ¬Motivation ¬Observations that lead to RNA ¬Features of RNA ¬Challenges ¬Related Work 1/2/2022

Motivation ¬Layers of a stack becoming more similar ¬Security, soft-state, pacing, retransmission ¬Desire to

Goals ¬Explore impact of layering ¬More than an code artifact ¬Support reuse ¬Avoid reimplementation

Internet Extensions Accused of ossification, but: ¬ Ossification = stability ¬ Plenty of extensions

Challenges: ¬Which to add… ¬IPv 4/IPv 6, TCP/DCCP/SCTP ¬When to add… ¬Security, muxing, cong.

RNA – fills the gaps ¬Between layers (left, from Choices) ¬Affects next-layer ¬Between stacks

RNA Metaprotocol ¬Template of basic protocol service: Shared State Security Flow Control Next Layer

Observations 1. Services are relative 2. A template can avoid recapitulation 3. Composition requires

The OSI 7 -layer Model ¬Layer indicates function Application Presentation ¬But… Session ¬Functions are

What makes a layer? ¬Its endpoints ¬A hop in a layer is the entire

Service is defined by context ¬Shared state exists at many layers, but supports different

Adding Services is Hard ¬Wedge between (IPsec, left) or replicate (virtualization, right) HTTP XDR

Recapitulation ¬ Component services repeat: ¬handshake / state management ¬security ¬policy (admission control, filtering)

Composition Requires Coordination ¬Many services integrate layers ¬Congestion control ¬Message boundaries ¬Security ¬State establishment

Features ¬As many layers as you need ¬Context sensitivity ¬Extends Choices’ Multi-Domain Communication Model

RNA Stack ¬Only needed layers ¬With only needed services ¬One MP, many instances ¬Configurable

Layer Context Sensitivity ¬E. g. , mp-1 morphs varies when over wireless vs. optical

MDCM from Choices ¬One template for ARP, BGP, IP, DNS LAYER(DATA, SRC, DST) ¬Also

Components of RNA MP Instantiate MDCM’s “Process DATA” ¬ Establish / refresh state ¬

Challenges ¬MP design ¬Building a sensible, generic template ¬Stack management ¬Supporting instantiation and composition

Related Work ¬ Modular protocol environments ¬ Click, x-Kernel, Netgraph, Flexible Protocol Stacks ¬

Current Status ¬Funding started 9/15/06 ; -) ¬(watch this space for future news) 1/2/2022

And now for something completely different… 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 24

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One Protocol / Many Layers: A Recursive Network Architecture Joe Touch Postel Center Director USC/ISI Research Assoc. Prof. USC CS & EE/Systems Depts. 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 1

Motivation ¬Layers of a stack becoming more similar ¬Security, soft-state, pacing, retransmission ¬Desire to support interlayer cooperation ¬Message boundary, cong. control, compression vs. encryption interactions ¬Desire to support overlay layers ¬Clearly needed, but don’t map to 1 -7 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 3

Goals ¬Explore impact of layering ¬More than an code artifact ¬Support reuse ¬Avoid reimplementation of features ¬Support coordination ¬Simpler to interface ‘to yourself’ ¬Support runtime composition ¬Extends X-Bone’s Choices model 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 4

Internet Extensions Accused of ossification, but: ¬ Ossification = stability ¬ Plenty of extensions refute bad connotation: ¬Shim layers: ¬HIP, SHIM 6, IPsec, TLS ¬Muxing layers: ¬SCTP, RDDP, BEEP ¬Connections: ¬MPLS, GRE, IKE, BEEP, SCTP ¬Virtualization: ¬L 2 VPN, L 3 VPN/X-Bone/RON/Detour, L 7 -DHTs 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 5

The OSI 7 -layer Model ¬Layer indicates function Application Presentation ¬But… Session ¬Functions are recapitulated: ¬Formatting at link and presentation ¬Muxing at transport and session 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. Transport Network Data link Physical 10

What makes a layer? ¬Its endpoints ¬A hop in a layer is the entire extent of the layer below (E 2 E argument goes here) ¬The layer above ¬What services this layer provides ¬The layer below ¬What services this layer requires 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 11

Service is defined by context ¬Shared state exists at many layers, but supports different services ¬App binding ¬Transport delivery ¬Net security ¬Difference is scope ¬Endpoints vary App Program Trans Process Net Host 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 12

Adding Services is Hard ¬Wedge between (IPsec, left) or replicate (virtualization, right) HTTP XDR BEEP TCP Virt. IP 802. 3 IP IP sec IP 802. 3 100 b. T 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 13

Recapitulation ¬ Component services repeat: ¬handshake / state management ¬security ¬policy (admission control, filtering) ¬multiplexing and demultiplexing ¬retransmission ¬reordering ¬pacing / congestion control ¬switching / forwarding ¬ Compounded by virtualization ¬Layer on layer 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 14

Composition Requires Coordination ¬Many services integrate layers ¬Congestion control ¬Message boundaries ¬Security ¬State establishment ¬Current interlayer interface is limited ¬Defined by each layer ¬No general security, state, etc. interface 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 15

RNA Stack ¬Only needed layers ¬With only needed services ¬One MP, many instances ¬Configurable like TP++ ¬Retain layers to limit scope RNA mp-4 RNA mp-3 RNA mp-2 RNA mp-1 physical 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 17

Layer Context Sensitivity ¬E. g. , mp-1 morphs varies when over wireless vs. optical ¬Opportunity for auto-tuning 1/2/2022 RNA mp-4 RNA mp-3 RNA mp-2 RNA mp-1’ wireless optical Copyright 2006, USC/ISI. All rights reserved. 18

MDCM from Choices ¬One template for ARP, BGP, IP, DNS LAYER(DATA, SRC, DST) ¬Also for BARP Process DATA, SRC, DST into MSG ¬Structured template ¬With plug-in funcs. WHILE (Here <> DST) IF (exists(lower layer)) Select a lower layer Resolve SRC/DST to lower layer S’, D’ LAYER(MSG, S’, D’) ELSE FAIL /* can’t find destination */ ENDIF ENDWHILE /* message arrives here */ RETURN {up the current stack} Next-hop Resolution Next Layer Resolution 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 19

Components of RNA MP Instantiate MDCM’s “Process DATA” ¬ Establish / refresh state ¬ Encrypt / decrypt message ¬ Apply filtering ¬ Determine whether to proceed based on flow control ¬ On input, determine whether to proceed based on reordering ¬ Multiplex/demultiplex as indicated (includes switching/forwarding) 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 20

Challenges ¬MP design ¬Building a sensible, generic template ¬Stack management ¬Supporting instantiation and composition ¬Supporting interlayer coordination ¬Designing a sensible, recursive API ¬Supporting context sensitivity ¬Detecting environment and autotuning 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 21

Related Work ¬ Modular protocol environments ¬ Click, x-Kernel, Netgraph, Flexible Protocol Stacks ¬ RNA adds a constrained template ¬ Template protocol models ¬ MDCM, RBA ¬ RNA adds structured sequence of services ¬ Context-sensitive protocols ¬ PEPs, Shims, intermediate overlay layers, etc. ¬ RNA incorporates this into the stack directly ¬ Configurable protocols ¬ XTP, TP++, SCTP ¬ RNA makes every layer configurable, but keeps multiple layers. 1/2/2022 Copyright 2006, USC/ISI. All rights reserved. 22