H3C Technologies H3C S7500E Series Switches - Manual (Page 154)

5-9
LAN IIHs; and the Level-2 routers use the Level-2 LAN IIHs. The P2P IIHs are used on point-to-point
networks.
Figure 5-7 illustrates the hello packet format in broadcast networks, where the blue fields are the
common header.
Figure 5-7 L1/L2 LAN IIH format
z Reserved/Circuit Type: The first 6 bits are reserved with a value of 0. The last 2 bits indicate the
router type. 00 means reserved, 01 indicates L1, 10 indicates L2, and 11 indicates L1/2.
z Source ID: System ID of the router advertising the hello packet.
z Holding Time: If no hello packets are received from the neighbor within the holding time, the
neighbor is considered down.
z PDU Length: Total length of the PDU in bytes.
z Priority: DIS priority.
z LAN ID: Includes the system ID and a one-byte pseudonode ID.
Figure 5-8 shows the hello packet format on the point-to-point networks.