Cloud Definable Networking: Mobile Content Distribution Network
Mobile Content Distribution Network (MCDN) is expected to deliver the content to the terminal users in an optimal manner through any kind of wireless network or mobile network [9]. As same as the traditional CDN, MCDN aims to provide the terminal users with the content ensuring the high availability and high performance.
Furthermore, MCDN can optimize the content delivering to the mobile devices through some particular wireless network, such as the limited network capacity and lower resolution. By enhancing the detection around the intelligent equipment, MCDN can solve the instinct challenges of the mobile network including the long delay, high packet loss rate, and large downloads [42].
MCDN is able to relief the traffic pressure of the core network by deploying CDN service nodes in the core mobile network or the lineside of wireless network. In the implementation of MCDN for the mobile network, the point is how to get the users’ IP data grouping for analysis and respond in advance. Therefore, it is possible to deploy the cache equipment at NE for MCDN, such as Evolved Node B (eNode B), Serving GPRS Support Node (SGSN), and Gateway GPRS Support Node (GGSN) in the core network, as shown in Fig. 4.2.4.2 Mobile Content Distribution Network
It is not appropriate to place MCDN storage node behind each eNode B, considering to the large number and wide distribution of eNode B. For the specific area containing a great many users, it is available to add Local Gateway (LGW) behind eNode B as a regional equipment, and the CDN is collaborative deployed behind LGW, as shown in Fig. 4.3. The existing network architecture keeps the same that the Packet Data Network Gateway (PGW) still serves as the provincial anchor equipment and the Mobility Management Entity (MME)/Serving Gateway (SGW) serves as the municipal anchor equipment. The function of the added LGW is the combination of SGW and PGW. Similar to SGW, LGW is under the control of MME, and LGW can include one or several eNode B. In the 3GPP draft, the LGW has been defined to realize the sideway CDN, but it hasn’t become a common accepted standard. This solution just needs a little change in the existing network, because the MME in the existing network supports the essential LGW and SGW.
Therefore, the new equipment can smoothly deploy in the network without new interface. LGW can be treated as a weakened version of the combination of SGW and PGW, which is suitable for some specific regions such as the busy commercial places and schools.
When the MCDN storage node is placed behind SGW, SGW can get the user’s complete IP data grouping. Moreover, SGW is always a municipal NE, which is appropriate to set MCDN cache. As shown in Fig. 4.4, the user’s NE is SGW in Evolved Packet Core (EPC) while the edge NE is PGW. After SGW gets the user’s IP request from the protocol stack, it can connect with MCDN cache equipment directly through Ethernet interface to transfer IP data grouping.
When the MCDN storage node is placed behind PGW, because the position of storage is near the coboundary of EPC, the traffic burden of core network is decreased a little after placing the cache node. In some degree, it is just like a usual CDN system.