GVRP网络协议帧

GVRP网络协议帧

GVRP（Generic VLAN Registration Protocol）基于GARP机制，主要用于维护设备动态VLAN属性。通过GVRP协议，一台设备上的VLAN信息会迅速传播到整个交换网。GVRP实现动态分发、注册和传播VLAN属性，从而达到减少网络管理员的手工配置量及保证VLAN配置正确的目的。
一、GVRP帧格式

+------------------------------------------------------------------------------+
|   DMAC    |   SMAC    |  Length |  DSAP  |  SSAP  |  Ctrl  |       PDU       |
+------------------------------------------------------------------------------+
                                                             |                 |
|                                                                |
+----------------------------------------------------------------+
|  Protocol ID  |  Message 1  |  ...  |  Message N  |  End Mark  |
+----------------------------------------------------------------+
                |             |
|                                         |
+-----------------------------------------+
|   Attribute Type   |   Attribute List   |
+-----------------------------------------+
                     |                    |
|                                                          |
+-----------------------------------------                 +
|   Attribute 1   |  ...  |   Attribute N   |   End Mark   |
+----------------------------------------------------------+
                          |                 |
|                                                             |
+----------------------------------------------------------   +
|  Attribute Length  |  Attribute Event   |  Attribute Value  |
+-------------------------------------------------------------+

二、GVRP帧格式释义

字段	长度	含义
Protocol ID	2字节	协议ID，取值为1。
Message	不固定	消息，每个Message由Attribute Type、Attribute List构成。
Attribute Type	1字节	属性类型，由具体的GARP的应用定义。对于GVRP，属性类型为0x01，表示属性取值为VLAN ID。
Attribute List	不固定	属性列表，由多个属性构成。
Attribute	不固定	属性，每个属性由Attribute Length、Attribute Event、Attribute Value构成。
Attribute Length	1字节	属性长度，取值是2～255，单位为字节。
Attribute Event	1字节	属性描述的事件，取值如下： 0：LeaveAll Event 1：JoinEmpty Event 2：JoinIn Event 3：LeaveEmpty Event 4：LeaveIn Event 5：Empty Event
Attribute Value	不固定	属性取值，GVRP的属性取值为VLAN ID，但LeaveAll属性的Attribute Value值无效。
End Mark	1字节	结束标志、GARP的PDU的结尾标志，以0x00取值表示。

三、GVRP帧格式示例

Frame 1: 104 bytes on wire (832 bits), 104 bytes captured (832 bits)
    Encapsulation type: Ethernet (1)
    Arrival Time: Jan  1, 1970 08:00:01.482070000 
    [Time shift for this packet: 0.000000000 seconds]
    Epoch Time: 1.482070000 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: 104 bytes (832 bits)
    Capture Length: 104 bytes (832 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:llc:stp:gvrp]
    [Coloring Rule Name: Routing]
    [Coloring Rule String: hsrp || eigrp || ospf || bgp || cdp || vrrp || carp || gvrp || igmp || ismp]
IEEE 802.3 Ethernet 
    Destination: Spanning-tree-(for-bridges)_21 (01:80:c2:00:00:21)
        Address: Spanning-tree-(for-bridges)_21 (01:80:c2:00:00:21)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
    Source: HuaweiTe_9a:68:51 (04:f9:38:9a:68:51)
        Address: HuaweiTe_9a:68:51 (04:f9:38:9a:68:51)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Length: 86
    Trailer: 9d243e03
Logical-Link Control
    DSAP: Spanning Tree BPDU (0x42)
        0100 001. = SAP: Spanning Tree BPDU
        .... ...0 = IG Bit: Individual
    SSAP: Spanning Tree BPDU (0x42)
        0100 001. = SAP: Spanning Tree BPDU
        .... ...0 = CR Bit: Command
    Control field: U, func=UI (0x03)
        000. 00.. = Command: Unnumbered Information (0x00)
        .... ..11 = Frame type: Unnumbered frame (0x3)
GARP VLAN Registration Protocol
    Protocol Identifier: 0x0001 (GARP VLAN Registration Protocol)
    Message 1
        Type: VID (0x01)
        Attribute 1
            Length: 4
            Event: Join Empty (1)
            Value: 2
        Attribute 2
            Length: 4
            Event: Join Empty (1)
            Value: 3
        Attribute 3
            Length: 4
            Event: Join Empty (1)
            Value: 4
        Attribute 4
            Length: 4
            Event: Join Empty (1)
            Value: 5
        Attribute 5
            Length: 4
            Event: Join Empty (1)
            Value: 6
        Attribute 6
            Length: 4
            Event: Join Empty (1)
            Value: 7
        Attribute 7
            Length: 4
            Event: Join Empty (1)
            Value: 8
        Attribute 8
            Length: 4
            Event: Join Empty (1)
            Value: 9
        Attribute 9
            Length: 4
            Event: Join Empty (1)
            Value: 10
        Attribute 10
            Length: 4
            Event: Join Empty (1)
            Value: 11
        Attribute 11
            Length: 4
            Event: Join Empty (1)
            Value: 12
        Attribute 12
            Length: 4
            Event: Join Empty (1)
            Value: 13
        Attribute 13
            Length: 4
            Event: Join Empty (1)
            Value: 14
        Attribute 14
            Length: 4
            Event: Join Empty (1)
            Value: 15
        Attribute 15
            Length: 4
            Event: Join Empty (1)
            Value: 16
        Attribute 16
            Length: 4
            Event: Join Empty (1)
            Value: 17
        Attribute 17
            Length: 4
            Event: Join Empty (1)
            Value: 18
        Attribute 18
            Length: 4
            Event: Join Empty (1)
            Value: 19
        Attribute 19
            Length: 4
            Event: Join Empty (1)
            Value: 20
        End of Mark
    End of Mark

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