Topology DiscoveryCorrelating different network topology layers in

heterogeneous environments

Diederik Vandevenne Dennis Pellikaan

February 8, 2013

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Introduction

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Research question

What are the challenges with the correlation of physical topologyinformation based on LLDP and logical topology information?

Working hypotheses

LLDP is mature enough and widely implemented, which makes it auseful protocol for topology discovery in heterogeneous networkenvironments

All information needed to correlate the different network topologylayers is available in the Management Information Base

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Link Layer Discovery Protocol

LLDP Data Unit

Chassis ID

Port ID

Time to Live

Optional fields

End of LLDPDU

Operation modes

Send onlyReceive onlySend and receive

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Topology based on LLDP

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Ethernet with STP

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VLANs

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IP

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Complete Topology

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Implementation

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Findings

Maturity of LLDP at SURFsara

124 devices83% supports LLDP9% does not support LLDP8% unknown

NOT all relevant information for topology discovery can be retrievedfrom standardized management information base objects

Not all standardized MIB objects are supported by all vendorsSome information can only be retrieved from proprietary MIB objects

Device IDs (ChassisID, IP address) must be unique

Layer two path finding might be needed to create a correct IP layertopology

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Conclussions

Challenges of topology discovery

LLDP is mature enough and widely implemented,which makes it a useful protocol for topology dis-covery purposes in heterogeneous network environ-ments

All information needed to correlate the differentnetwork topology layers is available in the man-agement information base

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Questions?

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