SPBM multicast address
Each SPBM node has a multicast address for each SPB VSI. This multicast address consists of one shortest path source identifier (SPSource ID) and one I-SID. The I-SID identifies an SPB VSI, and the SPSource ID identifies the node as a multicast source in the SPB VSI.
Figure 6: SPBM multicast address format
Table 2: SPBM multicast address fields
Field | Description |
|---|---|
M | 1-bit multicast flag. Its value is fixed at 1. |
L | 1-bit local flag bit. Its value is fixed at 1. |
TYP | 2-bit SPSource ID type. Its value is fixed at 0. |
SPSource ID | 20-bit SPSource ID. |
I-SID | 24-bit SPB VSI identifier. |
In Figure 6, LSB represents the lower 4 bits of a byte, and MSB represents the higher 4 bits of a byte. The first byte of an SPBM multicast address is identical to the combination of the first 4 bits of the SPSource ID field, the TYP field, the L field, and the M field. For example, the hexadecimal form of the first byte (E3) in the SPBM multicast address E386070006E9 is 11100011. This byte consists of 1110 (first 4 bits of SPSource ID), 00 (TYP), 1 (L), and 1 (M).