BIERv6 I-PMSI Tunnel Establishment

PMSI tunnels are logical channels established between PEs to transmit C-multicast data over the public network. An I-PMSI tunnel connects all PEs in the same MVPN and is typically used as the default tunnel for data forwarding.

Figure 1 shows the process of establishing a BIERv6 I-PMSI tunnel. PE1 is the sender PE, and PE2 and PE3 are receiver PEs.

Figure 1 Process of establishing a BIERv6 I-PMSI tunnel

Table 1 describes the process of establishing a BIERv6 I-PMSI tunnel.

**Table 1** BIERv6 I-PMSI tunnel establishment process
Step	Device	Description
1	PE1, PE2, and PE3	Complete basic network configurations, including BIERv6 network configurations.
2	PE1, PE2, and PE3	Configure BGP and MVPN.
3	PE1	Configure PE1 as a sender PE and set the I-PMSI tunnel type to BIER in the IPv6 MVPN I-PMSI view.
4	PE1	PE1 sends an Intra-AS I-PMSI A-D route to PE2 and PE3 through BGP peer relationships. The route carries the following information: MVPN RT: controls A-D route advertisement. The value is the export MVPN target configured on PE1. PTA: Tunnel Type: The tunnel type is BIER. Sub-domain-id: sub-domain ID of PE1. BFR-ID: BFR-ID of PE1. BFR-prefix: BFR-prefix of PE1. In G-BIER scenarios, in addition to MVPN RT and PMSI tunnel attribute information, the routes advertised by PE1 carry the MSID attribute, which contains the following information: IPv6 Address: MVPN Src.DTX SID Prefix Length: Src.DTX SID locator prefix length MSID Length: Src.DTX SID locator (128 - prefix length – args length)
5	PE2 and PE3	After receiving the route from PE1, PE2 and PE3 reply with a Leaf A-D route. The route carries the following information: Sub-domain-id: sub-domain ID of PE2 or PE3. The value must be the same as the sub-domain-ID of PE1. BFR-ID: BFR-ID of PE2 or PE3. BFR-prefix: BFR-prefix of PE2 or PE3.
6	PE1	After receiving the routes from PE2 and PE3, PE1 records PE2 and PE3 as MVPN members and sets their bit positions in the BIERv6 BitString corresponding to the tunnel to 1. Consequently, PE2 and PE3 join the BIERv6 I-PMSI tunnel.