 model. As such, IPv6 can be transported over great variety of layer 2 protocols. From the IPv6 point of view, the layer 2 protocols and the physical link types they provide can be divided into two main categories: point-to-point and shared links. In this section, we will focus only on the physical link types, listed in Table 3.4, that are commonly used by the 3GPP networks and often supported by 3GPP capable mobile handsets. There are also specifications for transmitting IPv6 over various other kinds of link types, which we are not addressing in this book. These specifications might be of interest for readers and SO are listed in Table 3.5. In addition to transporting IPv6 over physical mediums, various solutions for transporting IPv6 over IPv4 or other protocols have been defined. In this book, we will further discuss tunneling based approaches in Chapter 5. Introduction to IPv6 Table 3.4 Link types commonly supported by 3GPP handsets Description Reference RFC 2464 Transmission of IPv6 Packets over Ethernet Networks RFC 5072 IP Version 6 over PPP [100] RFC 6459 IPv6 in 3GPP EPS [101] Table 3.5 Link types not covered by this book Description Reference RFC 2467 IPv6 over FDDI Networks [102] RFC 2470 IPv6 over Token Ring Networks [103] RFC 2491 IPv6 over Non-Broadcast Multiple Access (NBMA) networks RFC 2492 IPv6 over ATM Networks [104] RFC 2590 IPv6 over Frame Relay Networks [105] RFC 3146 IPv6 over IEEE 1394 Networks [106] RFC 4338 IPv6, IPv4, and ARP over Fibre Channel [107] RFC 4944 IPv6 over IEEE 802.15.4 Networks [108] RFC 5121 IPv6 over IPv6 Convergence Sublayer over IEEE 802.16 Networks [109] RFC 5692 IP over Ethernet over IEEE 802.16 Networks [110] Perhaps to make some self-parody of IETF community's interest in defining IPv6 over foo, where the foo is practically anything that could theoretically transport IPv6 packets, IETF has published April 1st RFCs about how to transport IPv6 over avian carriers [111] and social networks [112]. 3.6.1 IPv6 over Point-to-point Links In IPv6 protocol-wise the most sign