IPv6 support

Prerequisite for MC IPv6 Redundancy is to synchronize PPPoEv6 and IPoEv6 subscribers between the nodes by MCS.

In PPPoE environment, SRRP is used to refresh the forwarding path (MAC addresses) in the access aggregation network (by gratuitous ARP). SRRP ensures that the upstream traffic is steered to the active BNG node (SRRP master state). In the downstream direction, the standby BNG directs traffic over to the active BNG node via a redundant-interface.

The IPv6 functionality currently relies on IPv4 based SRRP and IPv4 based redundant-interface. In other words, IPv4 is required to run on the access side as well as on the redundant-interface.

The redundant-interface is used in the downstream direction. Traffic arriving on the network links on the standby node is shunted over to the active node over the redundant-interface. This is required to ensure consistent QoS and accounting functionality across the nodes (upstream and downstream traffic on the access links for a subscriber must traverse the same BNG node). There is no IPv6 related CLI associated with the redundant-interface.

All IPv6 subscriber traffic that arrives on the standby node in the downstream direction is automatically shunted over the IPv4 redundant-interface to the active node. When IPv6 traffic arrives over the redundant-interface on the active node, it is either PPPoEv6 encapsulated or left as plain IPoEv6 before it is forwarded to the subscriber.

In the upstream direction (AN->BNG) the behavior is the following:

        config>service>ies | vprn>
            subscriber-interface <ip-int-name>
                ipv6
                    [no] link-local-address <ipv6-address>
            <ipv6-address>       : ipv6-address   - x:x:x:x:x:x:x:x
                                                    x:x:x:x:x:x:d.d.d.d
                                                     x [0..FFFF]H
                                                     d [0..255]D

Note that the current version of SRRP relies only on IPv4 routes. The connection between SRRP and IPv4 routes is done with the subnets with gw IP addresses defined under the subscriber-interfaces in the ESM context. This connection is needed so that SRRP can send Gratuitous ARP properly.

These are the cases for PPPoEv6 MC Redundancy that are supported:

numbered IPv6 only subscriber-interfaces (config>service>sub-if>ipv6 hierarchy) is not supported