The following considerations apply to signaling Rosen MVPN PIM packets over a BIER core.
The MTU of Rosen MVPN tunnels is hardcoded to 1468. For each MVPN, the PIM joins are packed into a single packet up to a size of 1468 bytes. MVPN signaling does not take into account the BIER header size when the Rosen tunnels are signaled over the BIER domain.
The configure service vprn pim mtu-over-head mtu-value command reduces the Rosen tunnel MTU to allow a BIER header to be added without exceeding the network MTU. The tunnel MTU is reduced by the number of bytes specified by the mtu-value parameter of the mtu-over-head command.