ificant implications of point-to-point links are the ones caused to IPv6 Neighbor Discovery procedures. Specifically, as by definition a point-to- point link has only two peers, link-layer addresses are not necessary and hence do not need to be discovered either. Furthermore, multicasting loses some meaning in these types of links - the sent packets always end up with the other peer. Of course, nodes keep on listen- ing to multicast addresses, and packets can be sent to 'all-nodes', 'all-routers', and similar multicast addresses. Support for multicast is required to allow IPv6 stacks to behave in link type agnostic manner. The lack of need for link-layer address discovery on these type of links has led, in some cases, to implementation optimizations as described in RFC 3316 [3]. Namely, implementations have been able to cut down on address resolution and next-hop determination logic. This has caused some issues that we discuss in Section 4.9.1. The point-to-point link setup protocols often come with features for negotiating some higher layer parameters. For PPP the possible parameters are listed below, and for the 3GPP network's links in Section 4.4.7. The IKEv2 can also be used to negotiate a point- to-point link, with client and RDNSS addresses, as we discussed in Section 3.5.3. Deploying IPv6 in 3GPP Networks Point-to-Point Protocol The 3GPP bearer model is point-to-point. This link type significantly resembles IPv6 over PPP [100] and is described in depth by 3GPP 23.060 [113] and 23.401 [114]. In fact, the 3GPP specifications did actually support PPP type of Packet Data Protocol (PDP) context until Release-8, but it saw very little to no real use. However, IPv6 over PPP [100] could be used on circuit switched data connections. While the Internet Protocol Control Protocol (IPCP) [115] of PPP allows negotiation of an IPv4 address itself, the IPv6 Control Protocol (IPv6CP) [100] is used only negotiate IPv6 IIDs. The IID negotiations allow skipping of DAD procedures for IPv6 addresses constructed using negotiated