ODC112036 IGMP Protocol Principle ISSUE1.00.ppt

ODC112036 IGMP Protocol Principle ISSUE1.00

1. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved
www.huawei.com
IGMP Protocol Principle

2. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 2
IGMPisInternetGroupManagement
Protocol,andisresponsibleforIP
multicastmember management.It
establishesandmaintainsthemulticast
membershipshipbetweenIPhostsand
multicastroutersconnectedtohosts.

3. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 3
Upon completion of this course, you will be
able to:
Understand IGMP protocol principle
Master IGMP configuration
Know the difference among versions
Understand IGMP snooping principle
Master IGMP snoopingbasic
configuration

4. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 4
Chapter 1Overview of IGMP Protocol
Chapter 2IGMP Protocol Mechanism
Chapter 3IGMP Snooping

5. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 5
IGMP protocol introduction
IGMP is works between hosts and multicast routers connected to the
hosts.
IGMP working mechanism:
Receiver hosts report group membership to sharing network.
Querier sends group membership query to sharing network segment
periodically.
Receiver hosts respond for query message.
Multicast routers refresh the group members according to the
response.

6. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 6
Multicastlayeredsystem
IGMP
PIM-DM PIM-SM DVMRP Others…
MSDP
GRE/TUNNEL
MVPN

7. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 7
IGMP development
IGMP
development
IGMPv3
IGMPv2
IGMPv1

8. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 8
Chapter 1Overview of IGMP Protocol
Chapter 2IGMP protocol mechanism
Chapter 3IGMP snooping

9. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 9
IGMPv1 packet format
Version
Version filed includes IGMP version ID, set it to 1
Type
Membership query (0x11)
Membership report (0x12)
Group address
When a membership report is being sent, the group address
field contains the multicast address.
In the case of membership query, this field is set to 0 and
ignored by the host.
Group address
Check sumreservedtypeversion
0 7 15 31

10. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 10
Participation of IGMPv1 group member
PC3
224.1.1.1
report
PC2PC1
RTA
Host sends IGMP
membership report in
hope that participating
in the multicast group

11. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 11
IGMPv1 query and response
Query
224.0.0.1
224.1.1.1
Report
IGMPv1
Querier
PC2PC1
RTA
PC3
IGMP querier sends
membership query to
all hosts (224.0.0.1) in
the subnet periodically.
PC2 sends membership
report first(destination
address:224.0.0.1)

12. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 12
IGMPv1 response suppressionmechanism
Query
224.0.0.1
224.1.1.1
Report
224.1.1.1
suppression
X
224.1.1.1
suppression
X
IGMPv1
Querier
PC2PC1
RTA
PC3
IGMP Querier sends
membership querier to
hosts (224.0.0.1) in the
subnet periodically
Other members
restrain sending
report after
detecting the report.
PC2 sends
membership report
first(destination
address:224.0.0.1)

13. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 13
IGMPv1 member leave
Membership query
X3
PC2PC1
RTA
PC3
Host leaves group
silently (without
sending report
Router sends
membership
query The router sends the
membership information again
if it does not receive the IGMP
report of this group (three
queries in total).
Router thinks no
multicast
members exist
after three queries
without response

14. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 14
IGMPv2 packet format (1)
Type
Membership query (0x11)
−Regular query: identify which multicast group is valid, that is
whether it has members in the group. The address is all 0.
−Specified group query: query whether there are members in
specified multicast group
Version 2 membership report(0x16)
Version 1 membership report(0x12)
Leaving message(0x17)
Type
Maximum
response time
Checksum
Group address
0 7 15 31

15. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 15
IGMPv2 packet format (2)
Maximum response time
Unit : 0.1 second
It is 100 by default, namely, 10 seconds
Check sum
Group address
When sending a regular query, the group address field is 0. When
sending a specified group query, the group address field should be
set .
In the message of member report or leaving group, the group
address field keeps the address for report or leaving

16. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 16
Participation of IGMPv2 members
When a host joins a multicast group, it sends one or multiple membership
reports to the multicast group right now.
224.1.1.1
Report
PC3
PC2PC1
RTA

17. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 17
IGMPv2 query and response
It has the suppression mechanism, the same as IGMPv1.
Increase the maximum response time.
Query
224.0.0.1
224.1.1.1
Report
224.1.1.1
Suppression
X
224.1.1.1
Suppression
X
IGMP
Querier
PC2PC1
RTA
PC3

18. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 18
IGMPv2 querier selection
RTA
192.168.1.1192.168.1.2
When Router starts,
it sendsIGMPv2
regular query to
destination
224.0.0.1
1
Query
224.0.0.1
1
Query
224.0.0.1
1
the routers receiving
regular query
compares source IP
address and Local
interface IP
2
2 2
IGMP querier
Router with
Small IP
address
becomes
querier
3
3
RTB

19. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 19
IGMPv2 member leaving
Leaving group
Report 224.0.0.2
224.1.1.1
X2
PC2PC1
RTA
PC3
Host sends leaving
group message to
224.0.0.2
Specified group
query 224.1.1.1
Router sends
specified group
query to 224.1.1.1
If no report of the group received
in the maximum response time
(default 1s),it sends specified
group query again
The router thinks no
multicast members exist
if no membership report
received after specified
group query twice.

20. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 20
Interoperation between IGMPv1 and v2
IGMPv1
IGMPv2
IGMPv1IGMPv1
IGMPv1query
224.0.0.1
224.1.1.1
IGMPv1 report
RTA
V2 host and V1 router

21. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 21
IGMPv2
IGMPv2 IGMPv1
224.1.1.1
IGMPv2 report
RTA
IGMPv2 query
224.0.0.1
224.1.1.1
IGMPv1 report
Host sends v1 report
V2 router sets a timer correlative
with group considering V1 host , it
is used to notice the LAN that there
is a V1 host in the group
V1 host and V2 router
Interoperation between IGMPv1 and v2

22. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 22
PC3
PC1 PC2
RTA
IGMPv1
IGMPv2
IGMPv1
IGMPv1
RTB
IGMPv2
IGMPv1
Hybrid version
Interoperation between IGMPv1 and v2

23. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 23
IGMP basic configuration
[RTA]multicast routing -enable
[RTA]interface ethernet0/0
[RTA-Ethernet0/0]ip address 172.16.1.3 255.255.255.0
[RTA-Ethernet0/0]igmp enable
[RTA-Ethernet0/0]igmp version 2
[RTB]multicast routing -enable
[RTB]interface ethernet0/1
[RTB-Ethernet0/1]ip address 172.16.1.1 255.255.255.0
[RTB-Ethernet0/1]igmp enable
[RTB-Ethernet0/1]igmp version 2
RTA
IGMPv2
PC
RTB

24. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 24
IGMP configuration verification
<RTD>displayigmp interface
Ethernet0/0 (172.16.1.1):
IGMP is enabled
Current IGMP version is 2
Value of query interval for IGMP (in seconds): 60
Value of other querier time out for IGMP (in seconds): 120
Value of maximum query response time for IGMP (in secot for
IGMP: 2
Value of startup query interval for IGMP (in seconds): 15
Value of last member query interval for IGMP (in seconds): 1
Value of query timeout for IGMP version 1 (in seconds): 400

25. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 25
[RTB]displayigmp group
Total 2 IGMP groups reported on this router
Ethernet0/1 (172.16.1.1): Total 2 IGMP Groups reported:
Group Address Last Reporter Uptime Expires
239.255.255.250 172.16.1.5 00:08:04 00:02:52
224.1.1.1 00:03:00
IGMP configuration verification

26. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 26
IGMPv3 overview
IGMPv3 is described in RFC 3376. (At present, it is not widely
supported)
It serves Source Specific Multicast (SSM) model.
Allow the host to receive some multicast groups from some
networks.
Enhance the control capability of host; the host can specify not only
multicast group but also multicast source.

27. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 27
IGMPv3 working mechanism
IGMPv3 query
224.0.0.1
PC3PC1 PC2
RTA
Router sends query to
224.0.0.1 periodically
Every host sends report
to indicate joining or
rejecting some
multicast groups.
G: 224.1.1.1
IN:10.1.1.1
10.1.2.1
Report
224.0.0.22
G:224.1.1.1
EX: null
Report
224.0.0.22
G:224.1.1.1
EX:10.1.1.1
G:224.1.2.2
IN:10.1.2.1
Report
224.0.0.22

28. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 28
IGMPv3 developments
Source = 1.1.1.1
Group = 224.1.1.1
Source = 2.2.2.2
Group = 224.1.1.1
R1 R2
R3
PC1
members of group 224.1.1.1
IGMPv3: JOIN 1.1.1.1, 224.1.1.1
LEAVE 2.2.2.2, 224.1.1.1
PC1 hopes to receive
packet from S =
1.1.1.1 not S = 2.2.2.2
Though IGMPv3,
specified source can
prune packet from S =
2.2.2.2

29. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 29
IGMP versions compare
IGMPv1 IGMPv2 IGMPv3
Rely on up layer
routing protocol
Select by itself
Querier
selection
Leave silently
Send leaving
packet initiative
Member
Leaving
mode
support support
Specified
Group
query
Not support support
join specified
source and
group
Not support
Not
support
Select by itself
Send leaving
packet initiative

30. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 30
Chapter 1Overview of IGMP Protocol
Chapter 2IGMP Protocol Mechanism
Chapter 3IGMP Snooping

31. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 31
IGMP Snooping overview
TheproblemofIGMPsnoopingmulticastpacketisbroadcastedatlayer
two.
IGMPsnoopingrunsatthelinklayerandisthemulticastconstraint
mechanismusedformanagementandcontrolofmulticastgroup,on
layer-2Ethernetswitch.
IGMPsnoopingestablishedMACmulticastaddresstablethough
listeningIGMPfromhost.

32. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 32
IGMP Snooping working mechanism
Whenlayer2EthernetswitchreceivestheIGMPmessagetransmitted
betweenthehostandrouter,theIGMPsnoopinganalyzesthe
informationcarriedintheIGMPmessage:
When the IGMP host report message from the host is listened, the
switch adds this host to corresponding multicast table.
When the IGMP leaving message from the host is listened, the
switch delete the multicast entry corresponding to this host.
The switch can establish and maintain MAC multicast address table by
continuously listening to the IGMP messages, and forward the multicast
messages from routers based on the MAC multicast address table.

33. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 33
IGMP Snooping working mechanism
INTERNET
Router runs
IGMP
Ethernet runs
IGMP snooping
IGMP query
IGMP report

34. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 34
IGMP Snooping establishes and maintains group
CPU
0
1
2 3 4 5
IGMP report
IGMP query
MAC address
Forwarding table
Port
01-02-030 1 3
IGMP report
224.1.2.3
PC1 PC2 PC4PC3

35. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 35
IGMP Snooping basic configuration
[Quidway]vlan 2
[Quidway-vlan2]port Ethernet 1/0/5
to Ethernet 1/0/8
[Quidway-vlan2]igmp-snooping enable
RTA
IGMPv2
RTB
PC1 PC2

36. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 36
IGMP snooping verification
[Quidway]display igmp -snooping group
Total 2 IP Group (s).
Total 2 MAC Group (s).
Vlan (id):2.
Total 2 IP Group (s).
Total 2 MAC Group (s).
Router port (s):Ethernet1/0/7 Ethernet1/0/8
IP group (s):the following ip group IP group address:224.1.1.1
Host port (s):Ethernet1/0/6
MAC group (s):
MAC group address:0100 -5e01-0101
Host port (s):Ethernet1/0/6
……

37. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 37
Summary
Whichtwotypesofpacketscan
IGMPv1provide?
Whatistheadditionalfunctionof
IGMPv2comparingtoIGMPv1?
The principle and function of IGMP
snooping?

38. Thank you
www.huawei.com