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