「ISIS」- Hello, IIH

用途说明

IIH:用于建立和维持邻接关系:
1)在广播网络中:Level-1 IS-IS Router 使用 Level-1 LAN IIH; Level-2 IS-IS Router 使用 Level-2 LAN IIH;
2)在点到点网络中,则使用 P2P IIH;

报文结构

这些字段:属于 PDU Specific Header 部分;处于 PDU Common Header 与 Variable Length Fidleds 之间;

Reserved/Circuit Type:表示路由器的类型(0x01表示L1;0x10表示L2;0x11表示L1/L2; );

Source ID:发出 Hello 报文的路由器的 System ID;

Holding Time: 保持时间。在此时间内如果没有收到邻接发来的 Hello 报文,则中止已建立的邻接关系;

R:保留位;

Priority:选举 DIS 的优先级,7bit,0~127。数值越大,优先级越高;
1)该字段只在 MA Network 中的Hello消息(LAN IIH 消息)携带;
2)P2P Network 的 Hello 消息(P2P IIH 消息)没有此字段,也没有此字段之前的R保留位;

LAN ID / System ID / Designated IS,是 DIS 的 ID(<System ID>.<PseudoNode ID>);
1)该字段只在 MA Network 中的 Hello 消息(LAN IIH 消息)携带;
2)在 P2P Network 的 Hello 消息(P2P IIH消息)没有此字段;

Local Circuit ID:本地链路 ID;
1)该字段只在 P2P Network 的 Hello 消息(P2P IIH 消息)携带;
2)在 MA Network 中的 Hello 消息(LAN IIH消息)没有此字段;

报文示例

Frame 368: 1514 bytes on wire (12112 bits), 1514 bytes captured (12112 bits) on interface -, id 0
IEEE 802.3 Ethernet 
Logical-Link Control
ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
ISIS HELLO
    .... ..11 = Circuit type: Level 1 and 2 (0x3)
    0000 00.. = Reserved: 0x00
    SystemID {Sender of PDU}: 0000.0000.7777
    Holding timer: 9
    PDU length: 1497
    .100 0000 = Priority: 64
    0... .... = Reserved: 0
    SystemID {Designated IS}: 0000.0000.7777.02
    Area address(es) (t=1, l=4)
        Type: 1
        Length: 4
        Area address (3): 49.0003
    IS Neighbor(s) (t=6, l=6)
    IP Interface address(es) (t=132, l=4)
    Protocols Supported (t=129, l=1)
    Restart Signaling (t=211, l=3)
    Multi Topology (t=229, l=2)
    Padding (t=8, l=255)
    Padding (t=8, l=255)
    Padding (t=8, l=255)
    Padding (t=8, l=255)
    Padding (t=8, l=255)
    Padding (t=8, l=151)

ISIS HELLO, IPv6

Frame 1209: 1514 bytes on wire (12112 bits), 1514 bytes captured (12112 bits) on interface -, id 0
IEEE 802.3 Ethernet 
    Destination: ISIS-all-level-1-IS's (01:80:c2:00:00:14)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
    Source: 38:39:cc:01:01:00 (38:39:cc:01:01:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Length: 1500
    [Stream index: 6]
Logical-Link Control
    DSAP: ISO Network Layer (0xfe)
        1111 111. = SAP: ISO Network Layer
        .... ...0 = IG Bit: Individual
    SSAP: ISO Network Layer (0xfe)
        1111 111. = SAP: ISO Network Layer
        .... ...0 = CR Bit: Command
    Control field: U, func=UI (0x03)
        000. 00.. = Command: Unnumbered Information (0x00)
        .... ..11 = Frame type: Unnumbered frame (0x3)
ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
    Intradomain Routing Protocol Discriminator: ISIS (0x83)
    Length Indicator: 27
    Version/Protocol ID Extension: 1
    ID Length: 6
    000. .... = Reserved: 0x0
    ...0 1111 = PDU Type: L1 HELLO (15)
    Version: 1
    Reserved: 0
    Maximum Area Addresses: 3
ISIS HELLO
    .... ..11 = Circuit type: Level 1 and 2 (0x3)
    0000 00.. = Reserved: 0x00
    SystemID {Sender of PDU}: 0000.0000.1111
    Holding timer: 30
    PDU length: 1497
    .100 0000 = Priority: 64
    0... .... = Reserved: 0
    SystemID {Designated IS}: 0000.0000.1111.01
    Area address(es) (t=1, l=4)
        Type: 1
        Length: 4
        Area address (3): 49.0001
    Protocols Supported (t=129, l=1)
        Type: 129
        Length: 1
        NLPID: IPv6 (0x8e)
            NLPID: 0x8e
    IPv6 Interface address(es) (t=232, l=16)
        Type: 232
        Length: 16
        IPv6 interface address: fe80::3a39:ccff:fe01:100
    IPv6 Global Interface Address (t=233, l=16)
        Type: 233
        Length: 16
        IPv6 Global interface address: 2000:12::1
    Multi Topology (t=229, l=2)
        Type: 229
        Length: 2
        IPv4 Unicast Topology (0x000)
    Restart Signaling (t=211, l=3)
        Type: 211
        Length: 3
        Restart Signaling Flags: 0x00
            .... .0.. = Suppress Adjacency: False
            .... ..0. = Restart Acknowledgment: False
            .... ...0 = Restart Request: False
    Padding (t=8, l=255)
        Type: 8
        Length: 255
    Padding (t=8, l=255)
        Type: 8
        Length: 255
    Padding (t=8, l=255)
        Type: 8
        Length: 255
    Padding (t=8, l=255)
        Type: 8
        Length: 255
    Padding (t=8, l=255)
        Type: 8
        Length: 255
    Padding (t=8, l=129)
        Type: 8
        Length: 129