SPB-PIM Gateway Controller Node (Controller) shares stream information between the local SPB domain and a foreign domain. The foreign domain is the PIM network Rendezvous point (RP) or another SPB domain Controller.
The following list outlines Controller functionality:
Note
PIM source discovery is either through MSDP or static configuration of foreign streams at the Controller.
The Controller advertises local SPB originated streams through MSDP to another PIM domain or another SPB domain.
The Controller refrences the Unicast IP route table to determine which Gateway has the best route to the PIM source. The Controller then assigns the stream to the selected Gateway.
The Controller Node has the following components:
Source Discovery (MSDP and static configuration)
Gateway Selection Controller
MSDP resides in the Controller BEB or Controller BCB and PIM network RP that want to advertise multicast source information between domains.
The multicast source resides in the Protocol Independent Sparse Module (PIM-SM) domain. The multicast source must be discovered by MSDP residing on the Gateway Controller in the SPB domain.
The multicast source resides in the SPB domain. The multicast source must be advertised to the neighboring PIM domain through MSDP peers.
Note
You can also configure multicast sources statically on the Controller. Static configuration is useful for SSM multicast group range streams in the foreign domain, which are not advertised by MSDP. Static configuration is also useful for when two SPB domains are connected through a PIM Gateway, and want to only advertise a subset of streams to each other, without enabling MSDP.
Sender IP address (S)
Group IP address (G)
VRF ID of the stream
RP of the source (optional)
The Gateway Selection Controller uses Layer 3 reachability information to reach S, which is retrieved from the ISIS IP Shortcuts (IPSC) database.
The VSN identifier (I-SID) is determined by using the VRF ID provided by MSDP.
Note
If multiple BEBs have a route to S, the BEB with the lowest Layer 3 metric is selected as the Gateway.
Note
If a Gateway link fails or the cost of the route changes, the selection process identifies the link failure as a route change and selects another best Gateway BEB.
Note
Among all the routes to the source of the foreign stream announced by different BEBs through ISIS, the route announced by the selected Gateway has the longest prefix match and has the lowest external route metric.
If multiple BEBs meet the Gateway selection criteria, a deterministic hash function of system ID, source IP address, and group IP address is used. The deterministic hash function is computed for each of the BEBs that meet the Gateway selection criteria. The BEB that generates the lowest hash value is selected as the Gateway for the stream.