PIM Register报文格式
当PIM-SM网络中出现活跃组播源时，源端DR向RP发送Register（注册）消息，进行源注册。Register消息只在PIM-SM中使用。
一、PIM Register消息格式
0 1 2 3
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
+-------+-------+---------------+-------------------------------+
|PIM Ver| Type | Reserved | Checksum |
+-+-+---+-------+---------------+-------------------------------+
|B|N| Reserved2 |
+-+-+-----------------------------------------------------------+
| |
. Multicast data packet .
| |
+---------------------------------------------------------------+
二、PIM Register消息格式释义
| 字段 | 长度 | 说明 |
|---|---|---|
| PIM Ver | 4比特 | PIM版本，值为2。 |
| Type | 4比特 | 消息类型，值为1。 |
| Reserved | 8比特 | 保留位。发送时此字段被清零，接收时不处理此字段。 |
| Checksum | 16比特 | 校验和。 |
| B | 1比特 | 边界位。 |
| N | 1比特 | 空注册位。 |
| Reserved2 | 30比特 | 保留位。发送时此字段被清零，接收时不处理此字段。 |
| Multicast data packet | 变长 | 组播数据报文。源端DR将接收到的组播数据报文封装在Register消息中发往RP。RP解封装后，学习到该组播数据报文的（S，G）信息。 |
三、PIM Register消息报文示例
Frame 1: 78 bytes on wire (624 bits), 78 bytes captured (624 bits)
Encapsulation type: Ethernet (1)
Arrival Time: Nov 11, 2009 17:39:46.999984860
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1257932386.999984860 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: 78 bytes (624 bits)
Capture Length: 78 bytes (624 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:vlan:ethertype:ip:pim:ip:udp:data]
[Coloring Rule Name: UDP]
[Coloring Rule String: udp]
Ethernet II, Src: 00:e0:fc:00:29:d6 (00:e0:fc:00:29:d6), Dst: 00:e0:fc:00:29:cf (00:e0:fc:00:29:cf)
Destination: 00:e0:fc:00:29:cf (00:e0:fc:00:29:cf)
Address: 00:e0:fc:00:29:cf (00:e0:fc:00:29:cf)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: 00:e0:fc:00:29:d6 (00:e0:fc:00:29:d6)
Address: 00:e0:fc:00:29:d6 (00:e0:fc:00:29:d6)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: 802.1Q Virtual LAN (0x8100)
802.1Q Virtual LAN, PRI: 6, CFI: 0, ID: 8
110. .... .... .... = Priority: Voice, < 10ms latency and jitter (6)
...0 .... .... .... = CFI: Canonical (0)
.... 0000 0000 1000 = ID: 8
Type: IP (0x0800)
Trailer: 80a3b662
Internet Protocol Version 4, Src: 10.2.2.3 (10.2.2.3), Dst: 10.2.3.4 (10.2.3.4)
Version: 4
Header Length: 20 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: 56
Identification: 0x4d90 (19856)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 255
Protocol: PIM (103)
Header checksum: 0x6504 [validation disabled]
[Good: False]
[Bad: False]
Source: 10.2.2.3 (10.2.2.3)
Destination: 10.2.3.4 (10.2.3.4)
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
Protocol Independent Multicast
0010 .... = Version: 2
.... 0001 = Type: Register (1)
Reserved byte(s): 00
Checksum: 0xdeff [correct]
PIM options
Flags: 0x00000000
0... .... .... .... .... .... .... .... = Border: No
.0.. .... .... .... .... .... .... .... = Null-Register: No
Internet Protocol Version 4, Src: 10.2.2.2 (10.2.2.2), Dst: 228.1.1.1 (228.1.1.1)
Version: 4
Header Length: 20 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: 28
Identification: 0x0000 (0)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 254
Protocol: UDP (17)
Header checksum: 0xd30a [validation disabled]
[Good: False]
[Bad: False]
Source: 10.2.2.2 (10.2.2.2)
Destination: 228.1.1.1 (228.1.1.1)
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
User Datagram Protocol, Src Port: 0 (0), Dst Port: 0 (0)
Source Port: 0 (0)
Destination Port: 0 (0)
Length: 8
Checksum: 0xfff7 [validation disabled]
[Good Checksum: False]
[Bad Checksum: False]
[Stream index: 0]
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