Ethernet protocol

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Ethernet Protocols

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Protocol & Standard Function

IEEE 802.3u Fast Ethernet

IEEE 802.3z Giga Bit Ethernet

IEEE 802.1D STP (Spanning Tree Protocol)

IEEE 802.1s MISTP (Multiple Instance STP)

IEEE 802.1w RSTP (Rapid STP)

IEEE 802.1p Priority Queuing, CoS

IEEE 802.1Q VLAN (Port based, GVRP)

IEEE 802.1ad VLAN (Q-in-Q)

IEEE 802.1ah VLAN (MAC-in-MAC)

IEEE 802.3ad Link Aggregation Control Protocol (LACP)

IEEE 802.3x Flow Control and Back-pressure

IEEE 802.3ah Ethernet OAM (Discovery, Event Notif, Loopback)

IEEE 802.1ag Ethernet OAM (CFM)

ITU-T/Y.1731 Ethernet OAM (CFM, PM)

ITU-T G.8032/Y.1344 E-SPRing Ethernet Ring Protection Switch

ITU-T G.8261/Y.1361 Timing and synchronization aspects in packet networks

IEEE 1588v2 Synchronization Protocol (PTP) in packet networks

Ethernet Protocols & Main Functions

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IEEE Standards

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Frame formats for Ethernet and IEEE 802.3

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Reserved MAC Addresses

Dest. Address Assignment

01:00:5E:xx:xx:xx Group Dest. Addr. (GDA)

FF:FF:FF:FF:FF:FF Broadcast Addr.

01:80:C2:00:00:00 BPDU (STP)

01:80:C2:00:00:01 Pause frame

01:80:C2:00:00:10 All LANs Bridge Management

01:80:C2:00:00:20 GMRP

01:80:C2:00:00:21 GVRP

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DSLAMPCATU-R

ATMBay Networks

Bay Networks

BRASATM

SwitchATM

Switch

1483

Ethernet

ATM

ADSLPHYPHY

Ethernet Ethernet

ATM

ADSL

ATM

STM-1

1483

Ethernet

ATM

STM-1 PHY

Ethernet

ADSL ATM ATM

PPPoE

PPP

IP

PPPoE

PPP

IP

PVC PVC

Protocols of ATM DSLAM

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Protocols of IP DSLAM

DSLAMPCATU-R

IP

BRASRouter

1483

Ethernet

ATM

xDSLPHYPHY

Ethernet Ethernet

PHY

Ethernet

xDSL Ethernet

PPPoE

PPP

IP

PPPoE

PPP

IP

PVC1483

Ethernet

ATM

xDSL PHY

Ethernet

RouterEthernet

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802.1d STP

The primary goals of Spanning Tree are as follows:

Elimination of loops in a bridged infrastructure;

Improved scalability in a large network;

Provision of redundant paths, which can be activated

upon failure.

The Bridge Protocol exchanges Bridge Protocol Data

Units (BPDUs) in Bridged LAN communication

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Find out the Root Bridge

which has lowest cost

and eliminate looping

Root

802.1d STP Principle

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Bridge Architecture

802.1d STP Architecture

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Operation of inter-bridge protocol

802.1d STP internal operation

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Forwarding and Filtering flow chart

802.1d STP flow chart

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Learning Process: Station A sends a frame to Station B

802.1d STP example

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Complete Filtering Database is built, Station B sends a frame to Station C

802.1d STP example cont.

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IGMP Overview

Rather than Unicast and Broadcast, Multicast delivers IP packets to

just a group of hosts on the network. IGMP (Internet Group

Multicast Protocol) is a Network Layer protocol used to establish

membership in a Multicast group

Multicast IP address are Class D IP address, from 224.0.0.0 to

239.255.255.255. They are also referred to as Group Destination

Address (GDA). For each GDA, there is an associated MAC

address. This GDA MAC address is formed by

01:00:5E:XX:XX:XX, followed by the latest 23 bits of the GDA

multicast IP address in hex.

For Example :

GDA 224.10.10.10 corresponds to MAC address 01:00:5E:0A:0A:0A ,

GDA 239.255.255.255 corresponds to MAC address 01:00:5E:FF:FF:FF

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IGMP Snooping

A layer-2 switch supported IGMP snooping can passively snoop

on IGMP Query, Report and Leave packets. It checks IGMP

packets passing through it, picks out the group registration

information, and configures multicasting accordingly.

Without IGMP snooping, multicast traffic is treated in the same

manner as broadcast traffic.

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What is a Virtual VLAN?

A VLAN is a switched network that is logically segmented on an

organizational basis, by functions, project teams, or applications

rather than on a physical or geographical basis.

A VLAN can be thought of as a broadcast domain that exists

within a defined set of switches.

Why need implement VLANs ?

• LAN Segmentation

• Security

• Broadcast Control

• Performance

• Network Management

• Communication between VLANs

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LAN Segmentation

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Types of VLANs

Tag-based VLAN

Untagged VLAN

- Port based

- MAC based

- Protocol based

- IP Subnet based

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VLAN Classification

When the switch receives a frame:

If the frame is untagged, the switch classifies the frame to a port-based VLAN. VID is not concerned.

If the frame is untagged, a port VLAN identifier (PVID) can be assigned for the port. Ingress traffic is associate with the PVID, and egress traffic is with VID.

If the frame is tagged, the switch uses the tagged VLAN ID to identify the broadcasting domain of the frame.

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Port-based VLAN (1)

Easy to configure, define egress ports for each port. VLAN only governs the outgoing traffic, and unidirectional Port-based VLAN can't across different switches, but,….

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Port-based VLAN (2)

Port Egress Port

port 0 all

port 1 all

port 2 all

port 3 all

port 4 all

port 5 all

port 6 all

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Port-based VLAN (3)

Port Egress Port

port 0 5

port 1 all except 0

port 2 all except 0

port 3 all except 0

port 4 all except 0

port 5 all

port 6 all except 0

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Port-based VLAN (4)

1

2

4

3

5

7

6

8

9

Ethernet

DSL 1

DSL 2

DSL 3

DSL 4

DSL 5

DSL 6

DSL 7

DSL 8

Port-based configuration for 8 DSL ports IP DSLAM

example of port filter configuration

Port Egress Port

Ethernet all

DSL 1 E

DSL 2 E

DSL 3 E

DSL 4 E

DSL 5 E

DSL 6 E

DSL 7 E

DSL 8 E

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Tag-based VLAN Overview

TPID has a defined value of 8100 in hex. When a frame has the EtherType equal to 8100, this frame carries the tag IEEE 802.1P / 802.1P.

VLAN ID has 12 bits and allow the identification of 4096 (2^12) VLANs. Of the 4096 possible VIDs, a VID of 0 is used to identify priority frames and value 4095 (FFF) is reserved, so the maximum possible VLAN configurations are 4,094.

802.1p

802.1q

8100

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How 802.1Q VLAN works (1)

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Each physical port has a parameter

called PVID. When a untagged frame

is received, the PVID is assigned to

it.

for example, the two stations

connected to the central trunk link in

the lower part of Figure. They are

VLAN-unaware and they will be

associated to the VLAN C, because

the PVIDs of the VLAN-aware

bridges are equal to VLAN C.

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The Forwarding Process decide to forward the received frames

according to the the Filtering Database

The Filtering Database consists of static registration entries

( SVLAN table) and dynamic registration entries (DVLAN

table).

SVLAN table is manually added and maintained by the

administrator.

DVLAN table is automatically learned via GVRP protocol, and

can't be created and upgraded by the administrator

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Filtering Database

Dynamic VLAN (DVLAN) table


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GVRP

The GARP VLAN Registration Protocol (GVRP)

defines a GARP Application that provides the

VLAN registration service GVRP supports the dynamic registration of

VLAN port members within a switch and

across multiple switches. GVRP is used to communicate VLAN

registration information to other VLAN-aware

switches, so that members of a VLAN can

cover a wide span of switches in a network.

GARP MulticastRegistration

Protocol (GMRP)

GARP VLANRegistration

Protocol (GVRP)

Generic Attribute Registration Protocol (GARP)

Logical Link ControlLLC SAP 0x42

Media Access Control

Physical Layer

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example of PVID assignment

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802.1ad Double Tagging

IEEE 802.1ad Q-in-Q VLAN : The primary benefit for the service

provider is reduced number of VLANs supported for the same

number of customers. Other benefits of this feature include:

PPPoE scalability. By expanding the available VLAN space from

4096 to approximately 16.8million (4096 times 4096), the number of

PPPoE sessions that can be terminated on a given interfaceis

multiplied.

When deploying Gigabyte Ethernet DSLAM in wholesale model,

you can assign the inner VLANID to represent the end-customer

virtual circuit (VC) and assign the outer VLAN ID to represent the

service provider ID.

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802.1Q Tunneling: Tunneling is a feature designed for service

providers who carry traffic of multiple customers across their

networks and are required to maintain the VLAN and Layer 2

protocol configurations of each customer without impacting the

traffic of other customers.

Using the 802.1Q tunneling feature, service providers can use only a

single VLAN to support a customer who has multiple VLANs.

The outer tag (metro tag) containing the VLAN ID unique to each

customer

802.1ad Double Tagging -cont.

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Normal, 802.1Q, and Double-Tagged Ethernet Packet Formats

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Double Tagging -- IEEE 802.1Q (Tunneling)

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The primary goals of Link Aggregation are as follows:

- Increased bandwidth

- Increased availability

- Load sharing

IEEE 802.3ad link aggregation enables you to group Ethernet

interfaces at the physical layer to form a single link layer

interface, also known as a link aggregation group (LAG) or

Bundle. For example, if you need 450 Mbps of bandwidth to

transmit data and have only a 100-Mbps Fast Ethernet link,

creating a LAG bundle containing five 100-Mbps Fast

Ethernet links is more cost effective than purchasing a single

Gigabit Ethernet link.

802.3ad Link Aggregation

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802.3ad Link Aggregation –cont.

The Link Aggregation Control Protocol (LACP) is a

mechanism for exchanging port and system information to

create and maintain LAG bundles. The LAG bundle distributes

MAC clients across the link layer interface and collects traffic

from the links to present to the MAC clients of the LAG

bundle.

LACP that can be used for automatic communication of

aggregation capabilities between Systems and automatic

configuration of Link Aggregation.

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Interface Stack for 802.3ad Link Aggregation

After configure the LAG bundle, you can route IP traffic over it or create a VLAN over it.Figure below displays the interface stack for 802.3ad link aggregation.

After configure the LAG bundle, you can route IP traffic over it or create a VLAN over it.Figure below displays the interface stack for 802.3ad link aggregation.

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Link Aggregation - Architecture

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Link Aggregation sublayer block diagram

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Link Aggregation Control Protocol (LACP)

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Port Trunking & Fail-Over Function

Technology

Ethernet protocol