vlan [compatibility mode]

7/31/2019 VLAN [Compatibility Mode]

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VLAN

Suman Pandey


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References D. Passmore, and J. Freeman, The Virtual

LAN Technology Report,http://www.3com.com/nsc/200374.html, March,1997

IEEE 802.1Q, IEEE Standard for Local and

Metropolitan Area Networks: Virtual BridgeLocal Area Networks, 1998 Meng Guo , Subrata Mazumdar , Discovery of

Spanning Trees in Virtual Bridged LAN , The

Quarterly Newsletter of SNMP Technology,Comment, and Events, Volume 9, Number 1,December, 2001


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Outline General Concepts of VLAN

What is VLAN ? Why use VLAN's? Different way to assign VLAN Membership. S annin Tree in VLAN

Frame processing and 802.1Q standard Different kind of logical VLAN architecture

Implementation Details of VLAN for TopologyDiscovery Different Vendor specific Solutions SPECTRUM VLAN manager implementation MIB used


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General Concepts of VLAN

Paper: The Virtual LANTechnology Report


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What is VLAN ? vendor-specific solution

and strategy, so definingit is an issue.

VLAN's allow a networkmanager to logically

segmen a n odifferent broadcastdomains.

multiple physical LAN

segments independent ofphysical location and cancommunicate as if theywere on a common LAN


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Why use VLAN's?

Performance

Formation of Virtual Workgroups

Simplified Administration

Reduced Cost Security


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VLAN Membership Membership by Port

Membership by MACAddress

M m r hi IP

port vlan

1 12 1

3 2

Subnet Address

disadvantage of thismethod is that itdoes not allow foruser mobility.


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M m r hi IP n

MAC Address vlan

1212354145121 1

2389234873743 1

3045834758445 2

Address 5483573475843 1

Advantage :

no reconfiguration needed

Disadvantage : VLAN membership must be

assigned initially.

performance degradation asmembers of different VLANs coexist

on a single switch port


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M m r hi IP

IP Subnet vlan

23.2.24 126.21.35 2

Subnet Address Advantage: Good for application-based VLAN

strategy

User can move workstations

eliminate the need for frame tagging

Disadvantage :

Performance/ looking for L3 address inpacket.

Less effective with protocols such asIPX, DECnet, or AppleTalk

unroutable protocols such as NetBIOS


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Frame Processing in VLAN envRole of Bridges

bridge on receiving data determines to whichVLAN the data belongs either by implicit orexplicit tagging [802.1Q].

e r ge a so eeps rac o mem ersin a filtering database which it uses to determinewhere the data is to be sent

all the bridges in the VLAN should contain thesame information in their respective filteringdatabases


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Active Topology of Network withBridges


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Tagging [802.1Q]

Ethernet Frame Tag Header:

Token Ring and Fiber Distributed Data

n er ace ag ea er:

TCI


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VLAN architecture going forwardInfrastructural VLAN Service-Based VLAN


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Other Details of the Report DHCP with VLAN

ATM with VLAN

VLAN Migration Strategy

Automatic configuration of VLAN


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Implementation Details of

VLAN for To olo Discover

Paper: Discovery of SpanningTrees in Virtual Bridged LAN


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Different Vendor specific Solutions Avaya's VLANMaster application - only works with

Avayas Cajun switches.

Aprisma's SPECTRUM VLAN Manager It uses theCabletron Discovery Protocol (CDP) to find all CDPcompatible 802.1Q switches in a domain

Cisco's VlanDirector uses Cisco Discovery Protocol(CDP) VlanDirector cannot manage any devices that donot run CDP.

3COM's Enterprise VLAN Manager

Granite open source C API/SDK to provision VLANconfigurations using SNMP for Riverstone products.


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MIB InformationMIB used

RFC1213-MIB BRIDGE-MIB (RFC 1493)

Q-BRIDGE-MIB (RFC 2674).

dot1dStpPort

dot1qPvid

dot1dStpPortState

dot1dStpPortDesignatedRoot dot1dStpPortDesignatedBridge

dot1dStpPortDesignatedPort


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Discovery of Spanning Trees and

VLANs

Steps Deduce the target Virtual Bridged LAN from an arbitrary

IP address in the Virtual Bridged LAN

Automaticall discover all the brid es in the tar et Virtual

Bridged LAN Collect spanning tree and VLAN related MIB variables

from the discovered brides using SNMP

Construct the spanning trees in the Virtual Bridged LAN

and associate the spanning trees with VLANs.


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Implementation Detail

They have used Avaya's

Cajun switches, and the STPis stored in PROMINET-MIB

Collecting Spanning Tree RelatedInformation

12


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Implementation Detail

Construction of Per-VLANSpanning Tree Spanning Tree of VLAN 12

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vlan [compatibility mode]

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