IP Multicast in a Site-to-Site VPN
Site-to-Site VPN Overview
Additional information for tunnel allocation and sizing devices can be found in the Cisco AVVID Network Infrastructure Enterprise Site-to-Site VPN Design SRND.
Tunnel Aggregation for Resiliency
Branch Office devices
To plan for proper tunnel aggregation and load distribution in the case of a head-end device failure, the following process should be used:
Start with the number of total branch devices to be aggregated at the head-end. Divide this number by the number of head-end devices.
Multiply the result by 2 for primary and secondary tunnels. This is the total tunnels per head-end device.
Allocate the primary tunnels to each head-end device in the arrangement shown in Figure 2 above (in green).
For each group, allocate the secondary tunnels in a round-robin fashion to all head-end devices except the one serving as a primary for that group. This arrangement is also shown in Figure 2 above (in yellow).
Check to see that each head-end device is now allocated the same number of total tunnels per head-end device.
Cisco AVVID Network Infrastructure IP Multicast Design