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ETH Zurich – Distributed Computing Group Roger Wattenhofer 1
Ratul Mahajan, Microsoft Research Roger Wattenhofer, Microsoft Research & ETH Zurich
On Consistent Updates in Software Defined Networks Ratul Mahajan, - - PowerPoint PPT Presentation
On Consistent Updates in Software Defined Networks Ratul Mahajan, - - PowerPoint PPT Presentation
On Consistent Updates in Software Defined Networks Ratul Mahajan, Microsoft Research Roger Wattenhofer, Microsoft Research & ETH Zurich ETH Zurich Distributed Computing Group Roger Wattenhofer 1 The Blind Spot of SDNs Current State
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Example
SDN Controller
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Example
SDN Controller
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Example
SDN Controller
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Example
SDN Controller
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Example
SDN Controller v1 v2 [Reitblatt et al., SIGCOMM 2012]
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Example
SDN Controller v1 v2 [Reitblatt et al., SIGCOMM 2012]
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Example
SDN Controller
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Dependencies
Version Numbers [Reitblatt et al.] + stronger packet coherence – version number in packets – switches need to store both versions v1 “Better” Solution [This paper] 𝑣 𝑤 𝑦 𝑧 𝑣 𝑤 𝑦 𝑧 𝑧 𝑦
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Minimum SDN Updates?
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Minimum Updates: Another Example
𝑥 𝑣 𝑥 𝑤
- r
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Minimum vs. Minimal
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Minimum vs. Minimal
No node can improve without hurting another node
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Minimal Dependency Forest
In the paper, we present an algorithm to compute such a minimal dependency forest.
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Main Contribution For a given consistency property, what is the minimal dependency possible?
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Consistency Space
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It’s not just how to compute new rules. It is also how to gracefully get from current to new configuration, respecting consistency.
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Architecture
Rule generator Update plan generator Plan optimizer and executor Routing policy Consistency property Network characteristics New rules Update DAG
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Update DAG
Insert rule 𝑠 at node 𝑣 Remove rule 𝑡 at node 𝑤 Insert rule 𝑢 at node 𝑥 Wait 10s Remove rule 𝑟 at node 𝑦 Insert rule 𝑞 at node 𝑧 Logical OR
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Multiple Destinations using Prefix-Based Routing
- No new “default” rule can be introduced without causing loops
- Solution: Rule-Dependency Graphs!
- Deciding if simple update schedule exists: [Vanbever et al., TON 2012]
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Breaking Cycles
Insert 𝑣𝑥 Remove 𝑣𝑤 Insert 𝑤𝑣 Insert 𝑥𝑤 Remove 𝑤𝑥 Remove 𝑥𝑣
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Breaking Cycles
Insert 𝑣𝑥 Remove 𝑣𝑤 Insert 𝑤𝑣 Insert 𝑥𝑤 Remove 𝑤𝑥 Remove 𝑥𝑣 Insert at 𝑥: dest 𝑤: 𝑥𝑤 Remove at 𝑥: dest 𝑤: 𝑥𝑤
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Architecture
Rule generator Update plan generator Plan optimizer and executor Routing policy Consistency property Network characteristics New rules Update DAG
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Breaking Cycles
Insert 𝑣𝑥 Remove 𝑣𝑤 Insert 𝑤𝑣 Insert 𝑥𝑤 Remove 𝑤𝑥 Remove 𝑥𝑣 Insert at 𝑥: dest 𝑤: 𝑥𝑤 Remove at 𝑥: dest 𝑤: 𝑥𝑤
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Are Minimal Dependencies Good?
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Are Minimal Dependencies Good?
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Are Minimal Dependencies Good?
Plan optimizer and executor
(But will fix it.)
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Architecture
Rule generator Update plan generator Plan optimizer and executor Routing policy Consistency property Network characteristics New rules Update DAG
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Evaluation
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Evaluation
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Summary
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At ETH Zurich, we’re looking for a colleague in networking! Please ask me for details.
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Thank You!
Questions & Comments?
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