igmp snooping handbook

Ed. 00

GSIM

IGMP Snooping Handbook

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2007 SAMSUNG Electronics Co., Ltd. All rights reserved.

GSIM IGMP Snooping Handbook

SAMSUNG Electronics Co., Ltd. I

INTRODUCTION

Purpose This manual introduces the IGMP Snooping function and describes how to configure and use it.

Document Content and Organization This manual comprises two chapters and a list of abbreviations as follows.

CHAPTER 1. IGMP Snooping Overview This chapter introduces the IGMP Snooping function.

CHAPTER 2. Using the IGMP Snooping This chapter describes how the IGMP Snooping menu is structured and how to use it.

ABBREVIATION This list provides explanations on the abbreviations used throughout this manual.

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Conventions The following types of paragraphs contain special information that must be carefully read and thoroughly understood. Such information may or may not be enclosed in a rectangular box, separating it from the main text, but is always preceded by an icon and/or a bold title.

WARNING

Provides information or instructions that the reader should follow in order to avoid personal injury or fatality.

CAUTION

Provides information or instructions that the reader should follow in order to avoid a service failure or damage to the system.

CHECKPOINT

Provides the operator with checkpoints for stable system operation.

NOTE

Indicates additional information as a reference.

Console Screen Output y The lined box with Courier New font will be used to distinguish

between the main content and console output screen text. y Bold Courier New font will indicate the value entered by the

operator on the console screen.


SAMSUNG Electronics Co., Ltd. III

Reference OfficeServ GSIM (GSIMT) User Manual This manual introduces the OfficeServ 7400 GSIM (GSIMT) which is an OfficeServ 7400 application and describes how to set up and use it.

Revision History

EDITION DATE OF ISSUE REMARKS

00 08. 2007. First Edition

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This page is intentionally left blank.


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TABLE OF CONTENTS

INTRODUCTION I Purpose .......................................................................................................................... I Document Content and Organization ............................................................................. I Conventions................................................................................................................... II Console Screen Output ................................................................................................. II Reference ..................................................................................................................... III Revision History............................................................................................................ III

CHAPTER 1. IGMP Snooping Overview 1 What is IGMP Snooping?................................................................................................... 1 IGMP Snooping Function................................................................................................... 2

CHAPTER 2. Using IGMP Snooping 3 Operation of IGMP Snooping ............................................................................................ 3

IGMP Report.................................................................................................................. 3 IGMP Query................................................................................................................... 4 IGMP Leave................................................................................................................... 5

Structure of IGMP Snooping in GSIM ............................................................................... 6 Test Scenarios .................................................................................................................... 7

Scenario #1/Multicast Traffic Filtering Function ............................................................. 7 Scenario #2/IGMP Snooping Join................................................................................ 10 Scenario #3/IGMP Snooping Leave............................................................................. 12 Scenario #4/IGMP Snooping Last Member Query....................................................... 14 Scenario #5/IGMP Snooping Querier .......................................................................... 15

TABLE OF CONTENTS

VI SAMSUNG Electronics Co., Ltd.

ABBREVIATION 17 A ~ I .............................................................................................................................17 L ~ V ............................................................................................................................18


SAMSUNG Electronics Co., Ltd. 1

CHAPTER 1. IGMP Snooping Overview This chapter introduces the IGMP Snooping function.

What is IGMP Snooping? The typical L2 switch processes multicast traffic as unknown or broadcast traffic. Hence packets are flooded to all ports in the same VLAN. It will not be a problem if all ports belong to the IGMP snooping group. However, if a host in the segment belongs to the group, bandwidth is seriously wasted. The IGMP snooping technology makes it possible for only active multicast group members to receive multicast packets. All groups which are learned through the IGMP snooping function are recorded in the group table together with the multicast group address and VLAN ID.

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IGMP Snooping Function It is possible to make multicast traffic allowed for specific ports only by using static configuration. However, this is not a proper method. The switch can allow multicast traffic to be passed or blocked for specific ports by looking into IGMP messages through IGMP snooping.

Query Report Include/Exclude Multicast Data

Receive Host 1

IGMP Snooping

Switch

Receive Host 1

Router



CHAPTER 2. Using IGMP Snooping This chapter describes how to operate and test IGMP Snooping.

Operation of IGMP Snooping

IGMP Report An IGMP report message is transmitted when the router queries or a host want to be a group member. The function operates as follows: 1. When a switch receives an IGMP report message, it obtains the multicast

MAC address, VLAN ID, and the port information from the message. 2. The switch searches the L2 table of the hardware by using the multicast

MAC address and VLAN ID as the key. 3. If there is an entry matched, the port is added to the L2 multicast table. 4. If the switch is waiting for a query response, the port is added to the

software multicast table, which is used to update the ports which have responded at the time when the response is timed out.

5. Finally, the IGMP report message is forwarded to an appropriate port

except the ports that received it before.

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IGMP Query The router sends an IGMP query message periodically to check whether hosts have left the group. If no IGMP report message arrives within the specified time (Response Timeout), the router decides that there is no group member among the hosts. The internal operation is as follows: 1. The router searches the L2 table for the MAC address which corresponds

to the All Router address. If not found, the port which received the message is added to the table.

2. The router retrieves the entry in the multicast table that corresponds to

the VLAN to which the IGMP query message was received and then sets Port BPM to 0.

3. The router changes its state to GEN_QUERY_STATE and starts the

timer. 4. Because the message forwarding from FFP to the switch is not blocked,

there is no special operation to be sent to the port.



IGMP Leave If a host which is a multicast group member no longer wants to be a member, it sends an IGMP leave message to the router. The router sends a query and deletes the group which does not send the IGMP leave message any longer. 1. The router obtains the multicast MAC address, VLAN ID, and the port

information from the IGMP leave message. 2. The switch searches the L2 table of the hardware by using the multicast

MAC address and VLAN ID as the key. 3. If there is an entry matched, the port is removed from the L2 multicast

table. 4. If there is no port that matches the multicast address, the port is removed

from the multicast table. 5. If the router is waiting for an IGMP query message, the port is removed

from the software multicast table, which is used to update the ports which have responded at the time when the message is timed out.

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Structure of IGMP Snooping in GSIM The structure of the ZebOS is as follows.

The packet received from the switch chip is sent to the ISL socket through the Linux Kernel. The ISL socket then chooses the L2 daemon and forwards the packet to the corresponding application. IGMP Snooping receives an IGMP message such as Join, Leave, and performs a multicast information update within the application and the switch chip.

NPF Bridge

ZebOS

UNUX KERNEL ISL SOCKET BACKEND

BCM API

BCM Adapt Layer

PACKET IO

IPI FORWARD

IOCTL

ISL SOCKET

IGMP Snooping Daemon



Test Scenarios

Scenario #1/Multicast Traffic Filtering Function Purpose Check whether the IGMP Snooping's multicast traffic filtering is functioning properly.

Environment Set the system as illustrated below.

DUTDUT

multicast traffic

port1 port2 3 4 5

L3 switchL3 switch

port2 3 4 5Port 2 3 4 5 DUT

Port 3 4 5 Port

Mul ticast traffic

L3 switch

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Settings

1. Disable IGMP Snooping. (The function is disabled by default.) 2. Set port 1s multicast filter to Forward Unregistered Group.

3. Check for the inbound multicast traffic in the SmartBits Port 2, 3, 4, 5.

Enable IGMP Snooping.



4. Check for inbound multicast traffic in SmartBits Ports 2, 3, 4, 5. Set port

1s multicast filter to Forward Unregistered Group.

5. Check for inbound multicast traffic in SmartBits Ports 2, 3, 4, 5.

Results

y When IGMP Snooping is disabled, multicast traffic should be flooding through all ports.

y When enabled, there should be no multicast traffic through any port as no port has joined the Group.

y Using the last setting, the multicast traffic should be flooding through all ports.

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Scenario #2/IGMP Snooping Join Purpose Check if the IGMP Snooping's Join and Group Membership are functioning properly.

Environment Test under the identical environment as in Scenario #1.

Settings

1. Enable IGMP Snooping.

2. Send the 224.1.1.1 IGMP report message from SmartBits Port 3. 3. Check whether multicast traffic is flooding through each port.



4. Set the Group Membership to 60000ms.

5. Send the 224.1.1.1 IGMP report message from the SmartBits Port 3.

Again, check if the multicast traffic is flooding after 60000ms.

Results Since only port 3 has joined the Group, it should have received the multicast traffic. After 60000ms, there should be no inbound multicast traffic in port 3.

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Scenario #3/IGMP Snooping Leave Purpose Check whether the IGMP Snooping's Leave and Immediate-Leave are functioning properly.


Settings

1. Send the 224.1.1.1 IGMP report message from SmartBits Port 3. 2. Check whether multicast traffic is flooding through each port. 3. Send the 224.1.1.1 IGMP Leave from the SmartBits Port 3. 4. Check whether multicast traffic is flooding through each port. 5. Enable Immediate Leave.



6. Send the 224.1.1.1 IGMP report message from SmartBits Port 3 to DUT

Port 3. 7. Send the 224.1.1.1 IGMP Leave from SmartBits Port 3, and then check if

the multicast traffic is flooding through DUT Port 3.

Results

y Since only port 3 has joined the Group, only port 3 should have received the multicast traffic.

y The multicast traffic forwarding should stop 1 second after sending the Leave message.

y When performing the Leave after setting the Immediate Leave, the forwarding should stop immediately after sending the Leave message.

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Scenario #4/IGMP Snooping Last Member Query Purpose Check whether the IGMP Snooping's Last Member Query is functioning properly.


Settings

1. Disable IGMP Snooping, then re-enable it. 2. Set the Last Member Query Interval to 5000 ms.

3. Send the Multicast Group 224.1.1.1 IGMP report message from the

SmartBits Port 3. 4. Send the Group 224.1.1.1 IGMP Leave from the SmartBits Port 3. 5. Check whether multicast traffic is flooding through each port.

Results The multicast traffic forwarding should stop after 5 seconds (5000 ms).



Scenario #5/IGMP Snooping Querier Purpose Check whether the IGMP Snooping's Querier is functioning properly.


Settings

1. Set the Max Response to 15000 ms, and the Other Query to 6000 ms.

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2. Enable the Querier.

3. Send the Multicast Group 224.1.1.1 IGMP report message from

SmartBits Port 3. 4. Send the Multicast Group 224.0.0.1 IGMP report message from

SmartBits Port 2. 5. Check the query received from port 3.

Results Due to the Querier function, the query message should be received 2 minutes after sending the initial query message. The corresponding Query's Max Response time should be set to 15 seconds.



ABBREVIATION

A AS Autonomous System ARP Address Resolution Protocol

B BPDU Bridge Protocol Data Unit

C CTI Computer Telephony Integration

D DNS Domain Name Server

G GPLIM Gigabit PoE LAN Interface Module GVRP GARP VLAN Registration Protocol

H HTTP Hypertext Transfer Protocol

I IGMP Internet Group Management Protocol

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L LAN Local Area Network

M MAC Media Access Control

N NAT Network Address Translation NTP Network Time Protocol

P PD Powered Device PoE Power over Ethernet PVC Permanent Virtual Circuit PVID Port VLAN Identification

Q QoS Quality of Service

R RMON Realtime Monitoring RSTP Rapid Spanning Tree Protocol

S SPQ Strict Priority Queuing STP Spanning Tree Protocol SNMP Simple Network Management Protocol

T TFTP Trivial File Transfer Protocol

V VLAN Virtual Local Area Network VoIP Voice Over IP

GSIM IGMP Snooping Handbook 2007 Samsung Electronics Co., Ltd. All rights reserved.

Information in this manual is proprietary to SAMSUNG Electronics Co., Ltd.

No information contained here may be copied, translated, transcribed or duplicated by any form without the prior written consent of SAMSUNG.

Information in this manual is subject to change without notice.

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