Enhancing Network Debugging with CherryPick in Software-Defined Datacenter Networks

 
CherryPick: Tracing Packet Trajectory
in Software-Defined Datacenter Networks
 
Praveen Tammana
   Rachit Agarwal
  Myungjin Lee
                  
University of Edinburgh
  
‡UC Berkeley
 
SDN-enabled datacenters
Flexible network management
Control plane policies to data plane rules
Debugging becomes more challenging
Ensuring data plane conforms with control plane
 
 
 
 
 
 
 
 
 
 
 
Debugging datacenter networks
Packet trajectory tracing
 
“Tracing” the path taken by the packet
Scalability: Switch flow rules, packet header space
Policy
: 
All packets from 1 to 3 should go through 4
 
 
Actual path : 1 - 6 - 3
mismatch
 
4
 
1
 
2
 
3
 
5
 
6
Checks whether packet followed
route as defined in policy
Helps to localize network problems
     Ex: misconfiguration, failures
Enabling packet trajectory tracing
Dst
Src
Insert
ingress link ID
Idea 1: Append link IDs at each hop 
 
User packet
Challenge: Packets traversing non-shortest paths
1
2
3
4
6
Large packet header space
as  path length increases
5
Enabling packet trajectory tracing
Dst
Src
 
Path id 1
 
Path id 2
# Switch flow rules   
   # Paths that contain switch
Idea 2: Maintain global path ID for each unique path 
Need one flow rule for
 each unique path id
# Paths in 48-ary fat-tree
4 hops : 576
 
           6 hops: 1.3 million !!
Challenge: Packets traversing non-shortest paths
Existing approaches
Naïve approach
Switches append ingress link ID into the packet header
Large number of header bits
PathletTracer
 
[HotSDN’14] 
and 
PathQuery
 
[HotSDN’14]
Switches insert or update path information in packet header
Large number of switch flow rules
NetSight
 
[NSDI’14]
Logs packet details at each hop
Need to collect large amount of data
Topology agnostic
Handles wide range of queries
 
CherryPick overview
 
Exploits the structure in data center topologies
    (e.g., fat-tree)
Observation: A small subset of links sufficient to
represent any end-to-end path
Scalability:
Minimal number of flow rules irrespective to path length
Packet header space requirement is close to state-of-the-art
 
 
 
 
Selectively picking links
Dst
Src
Pick ingress link
 
Core
 
Agg
 
ToR
Only one shortest path
from Core to Dst
 
User packet
All 4 hops: Pick 1 link
 
id-1
 
Core
 
Agg
4 hops
Picked link
Selectively picking links
Dst
Src
 
id-1
 
id-2
Pick ingress link
Only one shortest path
between selected links
For more details, please refer to our paper
 
id-1
All 6 hops: Pick 2 links
 
Agg
 
ToR
6 hops
Picked link
Picked link
Evaluation results for 48-ary fat-tree
 
       ToR Switch
 
 
1
0
5
 
1
0
7
 
Header space requirement
is close to PathletTracer
Independent of
path length
Conclusion
 
CherryPick
Simple and scalable packet trajectory tracing technique
Demonstrate efficacy under fat-tree topology
Feasibility:
 
Trace all 4- and 6-hop paths using double tagging
Low overhead: 
#OpenFlow rules = #Ports
Future work
Generalization to other datacenter topologies
Tracing trajectories of packets that do not reach destination
 
 
 
 
 
 
 
 
Thank You
 
Backup-slides
Selectively picking a minimum number of links
Dst
Src
Pick ingress link
Pick ingress link
 
id-1
 
id-3
 
id-2
Pick ingress link
All 8 hops: Pick 3 links
Slide Note
Embed
Share

Explore CherryPick, a technique for tracing packet trajectory in software-defined datacenter networks. It helps in debugging by ensuring data plane conforms with control plane policies, localizing network problems, and enabling packet trajectory tracing challenges like non-shortest paths. CherryPick leverages network topology structure for scalability and efficiency.

  • Network Debugging
  • Software-Defined Networking
  • Datacenter Networks
  • Packet Trajectory Tracing
  • CherryPick

Uploaded on Sep 10, 2024 | 0 Views


Download Presentation

Please find below an Image/Link to download the presentation.

The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.

E N D

Presentation Transcript


  1. CherryPick: Tracing Packet Trajectory in Software-Defined Datacenter Networks Praveen Tammana RachitAgarwal Myungjin Lee University of Edinburgh UC Berkeley

  2. Debugging datacenter networks SDN-enabled datacenters Flexible network management Control plane policies to data plane rules Debugging becomes more challenging Ensuring data plane conforms with control plane

  3. Packet trajectory tracing Tracing the path taken by the packet Scalability: Switch flow rules, packet header space Policy: All packets from 1 to 3 should go through 4 4 5 6 Checks whether packet followed route as defined in policy Helps to localize network problems Ex: misconfiguration, failures mismatch Actual path : 1 - 6 - 3 1 2 3

  4. Enabling packet trajectory tracing Challenge: Packets traversing non-shortest paths Idea 1: Append link IDs at each hop Insert ingress link ID Large packet header space as path length increases 5 User packet 4 6 Src Dst 1 2 3

  5. Enabling packet trajectory tracing Challenge: Packets traversing non-shortest paths Idea 2: Maintain global path ID for each unique path Path id 1 Path id 2 # Paths in 48-ary fat-tree Need one flow rule for each unique path id 4 hops : 576 6 hops: 1.3 million !! Dst # Switch flow rules # Paths that contain switch Src

  6. Existing approaches Na ve approach Switches append ingress link ID into the packet header Large number of header bits PathletTracer[HotSDN 14] and PathQuery[HotSDN 14] Switches insert or update path information in packet header Large number of switch flow rules NetSight[NSDI 14] Logs packet details at each hop Need to collect large amount of data Topology agnostic Handles wide range of queries

  7. CherryPick overview Exploits the structure in data center topologies (e.g., fat-tree) Observation: A small subset of links sufficient to represent any end-to-end path Scalability: Minimal number of flow rules irrespective to path length Packet header space requirement is close to state-of-the-art

  8. Selectively picking links Pick ingress link 4 hops id-1 Only one shortest path from Core to Dst Core Core Picked link Agg All 4 hops: Pick 1 link Agg User packet ToR Dst Src

  9. Selectively picking links 6 hops id-1 Only one shortest path between selected links id-1 Picked link Pick ingress link id-2 All 6 hops: Pick 2 links Agg Picked link ToR Dst Src For more details, please refer to our paper

  10. Evaluation results for 48-ary fat-tree ToR Switch Header space requirement is close to PathletTracer Minimal number of Independent of path length switch flow rules 107 105

  11. Conclusion CherryPick Simple and scalable packet trajectory tracing technique Demonstrate efficacy under fat-tree topology Feasibility: Trace all 4- and 6-hop paths using double tagging Low overhead: #OpenFlow rules = #Ports Future work Generalization to other datacenter topologies Tracing trajectories of packets that do not reach destination

  12. Thank You

  13. Backup-slides

  14. Selectively picking a minimum number of links id-1 Pick ingress link Pick ingress link Pick ingress link id-3 All 8 hops: Pick 3 links Dst Src id-2

More Related Content

giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#