PIM Register-Stop报文格式
在PIM-SM网络中，接收者不再通过RP接收发往某组播组的数据，或者RP不再为某组播组服务，或者组播数据转发路径已经由RPT切换到SPT，这三种情况下，RP将会向组播源端DR发送Register-Stop消息。组播源端DR收到Register-Stop消息后，停止使用Register注册消息封装组播数据报文，并进入注册抑制状态。Register-Stop消息只在PIM-SM中使用。
一、Register-Stop消息报文格式
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 |
+-------+-------+---------------+-------------------------------+
| Group Address (Encoded-Group format) |
+---------------------------------------------------------------+
| Source Address (Encoded-Unicast format) |
+---------------------------------------------------------------+
二、Register-Stop消息报文格式解释
| 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2。 |
| 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。 |
| Group Address | 32比特 | 组播组地址G。 |
| Source Address | 32比特 | 组播源地址S。 |
三、PIM Register-Stop消息报文示例
Frame 1: 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Encapsulation type: Ethernet (1)
Arrival Time: Nov 11, 2009 17:59:15.953249850
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1257933555.953249850 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:ethertype:vlan:ethertype:ip:pim]
Ethernet II, Src: 00:e0:fc:00:29:cf (00:e0:fc:00:29:cf), Dst: 00:e0:fc:00:29:d6 (00:e0:fc:00:29:d6)
Destination: 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)
Source: 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)
Type: 802.1Q Virtual LAN (0x8100)
802.1Q Virtual LAN, PRI: 7, CFI: 0, ID: 8
111. .... .... .... = Priority: Network Control (7)
...0 .... .... .... = CFI: Canonical (0)
.... 0000 0000 1000 = ID: 8
Type: IP (0x0800)
Padding: 00000000
Trailer: 00000000f0a5d204
Internet Protocol Version 4, Src: 10.2.3.4 (10.2.3.4), Dst: 10.2.2.3 (10.2.2.3)
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: 38
Identification: 0x1108 (4360)
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: 0xa19e [validation disabled]
[Good: False]
[Bad: False]
Source: 10.2.3.4 (10.2.3.4)
Destination: 10.2.2.3 (10.2.2.3)
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
Protocol Independent Multicast
0010 .... = Version: 2
.... 0010 = Type: Register-stop (2)
Reserved byte(s): 00
Checksum: 0xf2d8 [correct]
PIM options
Group: 228.1.1.1 (228.1.1.1)/32
Source: 10.2.2.2 (10.2.2.2)
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