IP Packet Format
IP Packets Product Documentation contains the main data transmission protocol used in a variety of packet formats, packet example. By IP Packets Product Documentation, be able to enhance understanding of various protocol packets.
IP Packets Product Documentation contains the main data transmission protocol used in a variety of packet formats, packet example. By IP Packets Product Documentation, be able to enhance understanding of various protocol packets.
IGMPv3 Membership Query Message
IGMPv3 Membership Queries are sent by IP multicast routers to query the multicast reception state of neighboring interfaces.
Packet Format
Figure 3-52 Format of IGMPv3 Query Message
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------
| Type = 0x11 | Max Resp Code | Checksum |
+---------------------------------------------------------------
| Group Address |
+---------------------------------------------------------------
| Resv |S| QRV | QQIC | Number of Sources (N) |
+---------------------------------------------------------------
| Source Address (1) |
+- -+
| Source Address (2) |
+- . -+
. . .
. . .
+- -+
| Source Address (N) |
+---------------------------------------------------------------
IGMPv3 query message is divided into the following types:
- General query message
- Group-Specific query message
- Group-and-Source-Specific query message
| Field | Length | Description |
|---|---|---|
| Type | 8 bit | Indicates the message type. The value is 0x11. |
| Max Resp Code | 8 bit | Indicates the maximum response time taken by a device to respond to a Query message, in 1/10 seconds. If the device does not respond to the query message within the maximum response time, the querier considers that the query expires. |
| Checksum | 16 bit | Indicates the checksum of the IGMP message. Before an IGMP message is sent, the checksum must be calculated and the calculated result must be filled in the field. When the message is received, the checksum must be checked before the message is processed. Thus, whether an error occurs during the transmission of the IGMP message can be judged. |
| Group Address | 32 bit | For general query messages, the value of this field is set to 0. For group-specific query messages and group/source query messages, the field is set as the IP address of the multicast group that is to be queried. |
| Resv | 4 bit | The Resv field is set to zero on transmission, and ignored on reception. |
| S | 1 bit | SWhen the bit is set to 1, all the other routers that receive the query message do not start the refresh timer, but the query message does not affect the querier election and the interaction between the router and hosts. |
| QRV | 3 bit | If the value of this field is not 0, it indicates the robustness variable used by the querier. If the robustness variable used by the querier is greater than 7, the field is set to 0. After receiving the query message, the router sets the value of the field to its robustness variable if the field carried in the message is not 0. |
| QQIC | 8 bit | Indicates the timeout period of a querier, in seconds. After receiving a query message, a non-querier device sets the field to the its query interval if the field carried in the message is not 0. |
| Number of Sources (N) | 16 bit | Indicates the number of groups contained in the message. For general query messages and group-specific query messages, the field is set to 0. For source/group-specific query messages, the field is not set to 0. The value of this field is limited by the MTU in the network. |
| Source Address [i] | 32 bit | Indicates the multicast source address. The number of multicast source addresses is limited by the field "Number of Sources". |
| Additional Data | - | If the Packet Length field in the IP header of a received Query indicates that there are additional octets of data present, beyond the fields described here, IGMPv3 implementations MUST include those octets in the computation to verify the received IGMP Checksum, but MUST otherwise ignore those additional octets. When sending a Query, an IGMPv3 implementation MUST NOT include additional octets beyond the fields described here. |
Packet Example
Figure 3-53 IGMPv3 Membership Query (General)
Frame 1: 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Arrival Time: Feb 21, 2010 10:44:45.242895590
Epoch Time: 1266720285.242895590 seconds
[Time delta from previous captured frame: 0.000000000 seconds]
[Time delta from previous displayed frame: 0.000000000 seconds]
[Time since reference or first frame: 0.000000000 seconds]
Frame Number: 1
Frame Length: 68 bytes (544 bits)
Capture Length: 68 bytes (544 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ip:igmp]
[Coloring Rule Name: Routing]
[Coloring Rule String: hsrp || eigrp || ospf || bgp || cdp || vrrp || gvrp || igmp || ismp]
Ethernet II (VLAN tagged), Src: 00:e1:fc:00:29:d7 (00:e1:fc:00:29:d7), Dst: IPv4mcast_00:00:01 (01:00:5e:00:00:01)
Destination: IPv4mcast_00:00:01 (01:00:5e:00:00:01)
Address: IPv4mcast_00:00:01 (01:00:5e:00:00:01)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
Source: 00:e1:fc:00:29:d7 (00:e1:fc:00:29:d7)
Address: 00:e1:fc:00:29:d7 (00:e1:fc:00:29:d7)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
VLAN tag: VLAN=20, Priority=Best Effort (default)
Identifier: 802.1Q Virtual LAN (0x8100)
000. .... .... .... = Priority: Best Effort (default) (0)
...0 .... .... .... = CFI: Canonical (0)
.... 0000 0001 0100 = VLAN: 20
Type: IP (0x0800)
Trailer: 77616861000000000000271266b0
Internet Protocol Version 4, Src: 192.168.0.1 (192.168.0.1), Dst: 224.0.0.1 (224.0.0.1)
Version: 4
Header length: 24 bytes
Differentiated Services Field: 0xc0 (DSCP 0x30: Class Selector 6; ECN: 0x00: Not-ECT (Not ECN-Capable Transport))
1100 00.. = Differentiated Services Codepoint: Class Selector 6 (0x30)
.... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00)
Total Length: 36
Identification: 0xc9d4 (51668)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 1
Protocol: IGMP (2)
Header checksum: 0xb994 [correct]
[Good: True]
[Bad: False]
Source: 192.168.0.1 (192.168.0.1)
Destination: 224.0.0.1 (224.0.0.1)
Options: (4 bytes)
Router Alert: Every router examines packet
Internet Group Management Protocol
[IGMP Version: 3]
Type: Membership Query (0x11)
Max Response Time: 10.0 sec (0x64)
Header checksum: 0xec5f [correct]
Multicast Address: 0.0.0.0 (0.0.0.0)
QRV=2 S=Do not suppress router side processing
.... 0... = S: Do not suppress router side processing
.... .010 = QRV: 2
QQIC: 60
Num Src: 0
Figure 3-54 IGMPv3 Membership Query(Join Group)
Frame 1: 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Arrival Time: Feb 21, 2010 10:46:29.012641360
Epoch Time: 1266720389.012641360 seconds
[Time delta from previous captured frame: 0.000000000 seconds]
[Time delta from previous displayed frame: 0.000000000 seconds]
[Time since reference or first frame: 0.000000000 seconds]
Frame Number: 1
Frame Length: 68 bytes (544 bits)
Capture Length: 68 bytes (544 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ip:igmp]
[Coloring Rule Name: Routing]
[Coloring Rule String: hsrp || eigrp || ospf || bgp || cdp || vrrp || gvrp || igmp || ismp]
Ethernet II (VLAN tagged), Src: 00:e1:fc:00:29:d7 (00:e1:fc:00:29:d7), Dst: IPv4mcast_00:00:01 (01:00:5e:00:00:01)
Destination: IPv4mcast_00:00:01 (01:00:5e:00:00:01)
Address: IPv4mcast_00:00:01 (01:00:5e:00:00:01)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
Source: 00:e1:fc:00:29:d7 (00:e1:fc:00:29:d7)
Address: 00:e1:fc:00:29:d7 (00:e1:fc:00:29:d7)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
VLAN tag: VLAN=20, Priority=Best Effort (default)
Identifier: 802.1Q Virtual LAN (0x8100)
000. .... .... .... = Priority: Best Effort (default) (0)
...0 .... .... .... = CFI: Canonical (0)
.... 0000 0001 0100 = VLAN: 20
Type: IP (0x0800)
Trailer: aaaa000000001e91356f
Internet Protocol Version 4, Src: 192.168.0.1 (192.168.0.1), Dst: 232.0.0.1 (232.0.0.1)
Version: 4
Header length: 24 bytes
Differentiated Services Field: 0xc0 (DSCP 0x30: Class Selector 6; ECN: 0x00: Not-ECT (Not ECN-Capable Transport))
1100 00.. = Differentiated Services Codepoint: Class Selector 6 (0x30)
.... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00)
Total Length: 40
Identification: 0xca0b (51723)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 1
Protocol: IGMP (2)
Header checksum: 0xb159 [correct]
[Good: True]
[Bad: False]
Source: 192.168.0.1 (192.168.0.1)
Destination: 232.0.0.1 (232.0.0.1)
Options: (4 bytes)
Router Alert: Every router examines packet
Internet Group Management Protocol
[IGMP Version: 3]
Type: Membership Query (0x11)
Max Response Time: 1.0 sec (0x0a)
Header checksum: 0x3df2 [correct]
Multicast Address: 232.0.0.1 (232.0.0.1)
QRV=0 S=SUPPRESS router side processing
.... 1... = S: SUPPRESS router side processing
.... .000 = QRV: 0
QQIC: 0
Num Src: 10
Source Address: 192.0.1.0 (192.0.1.0)
Reference
| Standard | Description |
|---|---|
| RFC 3376 | Internet Group Management Protocol, Version 3 |
Protocol Stack
The IGMPv3 Membership Query message is encapsulated in IP, and the value of the protocol type field in the IP header is 0x02, indicating that the IGMP message is encapsulated in the data part. The destination address field in the IP header identifies the destination address of the IGMP message. The time to live (TTL) value in the IP header is 1, indicating that the IGMP message is transmitted only in the local network segment.
Figure 3-55 IGMPv3 Encapsulation
+-------------------------------+ | IGMPv3 | +-------------------------------+ | IP (Protocol = 0x02) | +-------------------------------+ | L2 | +-------------------------------+ | L1 | +-------------------------------+
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