Tunnel Services PICs and Multicast
On Juniper Networks routers, data packets are encapsulated and de-encapsulated into tunnels by means of hardware and not the software running on the router processor. The hardware used to create tunnel interfaces on M Series and T Series routers is a Tunnel Services PIC. If Juniper Networks M Series Multiservice Edge Routers and Juniper Networks T Series Core Routers are configured as rendezvous points or IP version 4 (IPv4) PIM sparse-mode DRs connected to a source, a Tunnel Services PIC is required. Juniper Networks MX Series Ethernet Services Routers do not require Tunnel Services PICs. However, on MX Series routers, you must enable tunnel services with the tunnel-services statement on one or more online FPC and PIC combinations at the [edit chassis fpc number pic number] hierarchy level.
 | Caution: For redundancy, we strongly recommend that each routing device has multiple Tunnel Services PICs. In the case of MX Series routers, the recommendation is to configure multiple tunnel-services statements. We also recommend that the Tunnel PICs be installed (or configured) on different FPCs. If you have only one Tunnel PIC or if you have multiple Tunnel PICs installed on a single FPC and then that FPC is removed, the multicast session will not come up. Having redundant Tunnel PICs on separate FPCs can help ensure that at least one Tunnel PIC is availble and that multicast will continue working. On MX Series routers, the redundant configuration looks like the following example: [edit chassis]user@mx-host# set fpc 1 pic 0 tunnel-services bandwidth 1g user@mx-host# set fpc 2 pic 0 tunnel-services bandwidth 1g |
In PIM sparse mode, the source DR takes the initial multicast packets and encapsulates them in PIM register messages. The source DR then unicasts the packets to the PIM sparse-mode RP router, where the PIM register message is de-encapsulated.
When a router is configured as a PIM sparse-mode RP router (by specifying an address using the address statement at the [edit protocols pim rp local] hierarchy level) and a Tunnel PIC is present on the router, a PIM register de-encapsulation interface, or pd interface, is automatically created. The pd interface receives PIM register messages and de-encapsulates them by means of the hardware.
If PIM sparse mode is enabled and a Tunnel Services PIC is present on the router, a PIM register encapsulation interface (pe interface) is automatically created for each RP address. The pe interface is used to encapsulate source data packets and send the packets to RP addresses on the PIM DR and the PIM RP. The pe interface receives PIM register messages and encapsulates the packets by means of the hardware.
Do not confuse the configurable pe and pd hardware interfaces with the nonconfigurable pime and pimd software interfaces. Both pairs encapsulate and de-encapsulate multicast packets, and are created automatically. However, the pe and pd interfaces appear only if a Tunnel Services PIC is present. The pime and pimd interfaces are not useful in situations requiring the pe and pd interfaces.
If the source DR is the RP, then there is no need for PIM register messages and consequently no need for a Tunnel Services PIC.
When PIM sparse mode is used with IP version 6 (IPv6), a Tunnel PIC is required on the RP, but not on the IPv6 PIM DR. The lack of a Tunnel PIC requirement on the IPv6 DR applies only to IPv6 PIM sparse mode and is not to be confused with IPv4 PIM sparse-mode requirements.
Table 1 shows the complete matrix of IPv4 and IPv6 PIM Tunnel PIC requirements.
Table 1: Tunnel PIC Requirements for IPv4 and IPv6 Multicast
IP Version | Tunnel PIC on RP | Tunnel PIC on DR |
|---|---|---|
IPv4 | Yes | Yes |
IPv6 | Yes | No |
