Auto-discovery
NG-MVPN uses BGP for PE auto-discovery (AD) and BGP MVPN routes for customer multicast signaling (C-Multicast Routes).
The BGP-based auto-discovery is implemented with a dedicated address family defined in RFC 4760 MP_REACH_NLRI/MP_UNREACH_NLRI attributes. There are two address families: MVPN-IPv4 for IPv4 <S,G>s and MVPN-IPv6 for IPv6 <S,G>s.
In NG-MVPN, the PMSI tunnel type defines the transport mechanism connecting Provider Edge (PE) routers. A PE uses this attribute to advertise its MVPN presence to other PEs. Available tunnel options include PIM (ASM/SSM), mLDP, RSVP-TE P2MP, BIER, and SR-P2MP.
Any PE connecting to an MVPN must send a BGP update message with an NLRI in the address family and specific attributes. The PE router uses route targets to define MVPN import and export routes. The route target can match or differ from the corresponding unicast VPN route target. The PE router may also assign separate import route targets for sender and receiver sites within a specific MVPN. The route distinguisher (RD) that is used for the corresponding unicast VPN can also be used for the MVPN.
The exchange of multicast information can be carried out using different protocols, such as PIM or BGP, depending on the deployment model, as summarized in the following table. SR Linux supports Option 6 as defined in RFC 6513 and RFC 6514.
| Protocol options | PMSI | Auto-discovery | C-multicast signaling | S-PMSI creation |
|---|---|---|---|---|
| Option 1 | PIM ASM | PIM (requires PIM Hello messages) | PIM join/leave | PIM SSM with S-PMSI join TLV |
| Option 2 | PIM ASM | BGP A/D route (no PIM Hello message required) | PIM join/leave | PIM SSM with S-PMSI join TLV |
| Option 3 | PIM SSM | BGP A/D route (no PIM Hello message required) | PIM join/leave | PIM SSM with S-PMSI join TLV |
| Option 4 | PIM ASM | BGP A/D route (no PIM Hello message required) | BGP source or shared join | BGP S-PMSI A/D route |
| Option 5 | PIM SSM | BGP A/D route (no PIM Hello message required) | BGP source or shared join | BGP S-PMSI A/D route |
| Option 6 | mLDP | BGP A/D route (P2MP or MP2MP) | BGP source or shared join | BGP S-PMSI A/D route (P2MP) |
| Option 7 | RSVP-TE P2MP | BGP A/D route (P2MP) | BGP source or shared join | BGP S-PMSI A/D route (P2MP) |
| Option 8 | BIER | BGP A/D route (P2MP) | BGP source or shared join | BGP S-PMSI A/D route (P2MP) |
| Option 9 | SR-P2MP | BGP A/D route (P2MP) | BGP source or shared join | BGP S-PMSI A/D route (P2MP) |