1 large-scale (campus) lan design (part ii) vlans hierarchical lan design
DESCRIPTION
3 Single-switch VLANsTRANSCRIPT
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Large-scale (Campus) Lan design (Part II) VLANs
Hierarchical LAN design
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Virtual LANs (VLANs) VLANs consist of end systems that are
members of a single logical broadcast domain.
A VLAN has no physical proximity constraints for the broadcast domain
A VLAN can span various pieces of network equipment that support VLAN trunking protocols between them
Without a router, hosts in 1 VLAN can’t communicate with hosts in another VLAN
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Single-switch VLANs
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VLAN Benefits VLANs break networks into smaller
broadcast domains
VLANs provide security
Easier network management
Well-behaved VLANs usually follow 80/20 network design rule
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VLAN Example
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VLAN Trunking Trunk – high-speed connection
between internetworking devices
Switches use Trunking protocol to exchange information about VLAN configuration (e.g. IEEE 802.1Q, Cisco’s ISL)
With trunking, tags are added to all the frames traveling on the trunk
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VLANs are shared through trunks
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VLAN Implementation By port – each port must belong to only 1
VLAN
By protocol – single port can support more than 1 VLAN
By a user-defined value – e.g. MAC address
Single switch VLANs
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Multi-switch VLANs
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Backbone Traditional
Collapsed
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Redundancy in the Backbone
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Distributed backbone (multiple collapse points)
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Distributed backbone (multiple collapse points)
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Hierarchical Design Access Distribution Core
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Hierarchical Design
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Central Routing
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Distributed Routing
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Small campus
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Medium campus
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Large campus