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Bluetooth

• Bluetooth Architecture

• Bluetooth Applications

• The Bluetooth Protocol Stack

• The Bluetooth Radio Layer

• The Bluetooth Baseband Layer

• The Bluetooth L2CAP Layer

• The Bluetooth Frame Structure

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Bluetooth Architecture

Two piconets can be connected to form a scatternet.

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Bluetooth Applications

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802.15 version of the Bluetooth protocol

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The Bluetooth Frame Structure

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Data Link Layer Switching

• Bridges from 802.x to 802.y• Local Internetworking• Spanning Tree Bridges• Remote Bridges• Repeaters, Hubs, Bridges,

Switches, Routers, Gateways• Virtual LANs

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Data Link Layer Switching

Multiple LANs connected by a backbone to handle a total load higher than the capacity of a single LAN.

Rationale for bridges

* Various departments within corporate/universities.* Geographical spread of LANs.* Split big LAN to accommodate the load.* Physical distance between machines.* Reliability.* Bridges contribute to the security.

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LAN bridge from 802.11 to 802.3

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The IEEE 802 frame formats

Bridging different LANs must: use protocol conversion, buffering for speed difference, accommodating maximum frame lengths, encryption handling.

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Local Internetworking

Bridge works in promiscuous mode: accepts any frame on any of the ports.It forwards the frame according to the forwarding table

(destination address, port).

Initially table is empty. Bridge uses flooding algorithm: forwards frame to every port except the one the frame came from.

Bridge learns backward: it builds up forwarding table by using (source address, arriving port)

To accommodate topology changes every 2 min forwarding table is updated.

1. If destination and source LAN same discard frame.2. If destination and source LAN different forward frame.3. If destination LAN unknown use flooding.

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Two parallel bridges

Loop through flooding, F destined for LAN3: both bridges forward F to LAN2 -> F1, F2. B2 forwards F1 to LAN1 -> F3, and B1 forwards F2 to LAN1 -> F4. B1 forwards F3 to LAN2, and B2 forwards F4 to LAN2, etc.

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Spanning Tree Bridges

Original extended LAN (a) is a graph with LANs as nodes and bridges as arcs (b). A spanning tree is the overlay graph without loops: there is only one path fro any LAN to any LAN. The dotted lines are not part of the spanning tree. Plug and play spanning tree algorithm is standardized by IEEE 802.1D.

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Remote Bridges used to interconnect distant LANs

Bridges are interconnected by hostless LANs. They might use PPP:complete MAC frame is payload for PPP - inverse encapsulation.Inverse or equal encapsulation is called tunneling.

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Repeaters, Hubs, Bridges, Switches, Routers and Gateways by Layer

(a) Which device is in which layer: different devices use different information for switching.

(b) Frames, packets, and headers.

Repeater is analog device between two coax ends. They understand volts.

Classic Ethernet allows up to 4 repeaters to extend LAN from 500 m to 2500 m.

Gateways here are protocol converters.

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Hubs, Bridges, Switches

(a) Hub: do not amplify. Single collision domain.

(b) Bridge: connects LANs (broadcasts frames), has a line cards with 4 to 8 ports each, each port is a collision domain.

(c) Switch: connects individual hosts, forwards frame to single user, each port

is a single user - no collision, old implementation is store-and-forward, new

implementation is “cut-through” - as soon as destination address arrives switch starts forwarding the frame.

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Physical LAN with twisted pair

Logical LAN was obtained by connecting to physical hub.There are as many hubs as virtual LANs. Why logical LANs: broadcasting (failure - babblers), security, unloading.VLAN - decoupling logical from physical topology.

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Virtual LANs (G-gray and W-white) bridge and switch implementation

Configuration tables tell which VLAN is accessible via which port. E.g. frame

coming from A must be forwarded by B1 to all G ports except the input port.

How to know which host belongs to which VLAN w/out manual intervention?

New Ethernet frame with VLAN identifier field -> IEEE 802.1Q.

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The IEEE 802.1Q Standard

Transition from legacy Ethernet to VLAN-aware Ethernet.

The shaded symbols are VLAN aware. The empty ones are not.

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The 802.3 (legacy) and 802.1Q Ethernet frame formats.

12 bits3 bits

Switches/bridges add VLAN id to backward learning.

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Allocation methods for a common channel

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