The unique Chinese need for multi-operator access is the high school campus network. Students can use the Internet to export in their dormitories, or to choose between telecommunications, connectivity, or mobile broadband exports. Different types of telecommunication strategies and bandwidth standards are used for different exports.——If you have a problem at any point, the student complains that the network is not working quickly, and then the operator and school settle disputes.
The technology architecture in multi-operability business settings is centred on the BRAS equipment and RADIUS protocol. Users not only enter a password for their account on the Portal authentication page, but also select operators from a dropdown menu. This option is passed to backstage certification servers through the RADIUS protocol. Standard practice is to use the private property field of RADIUS to transmit domain names. After BRAS receives access-Accept messages, import user traffic into corresponding VPN examples or VRFs based on domain name fields. The export links of different operators are tied to different VPN examples, and the user's up-and-down flow is isolated into different logical channels without interference. This program is well developed in a network at the operator level, with direct re-use of the campus network.
The structure seems clear, but there are details that can be encountered in actual deployment. Most typically DNS deconstruct conflicts. Different operators may have a differentiated resolution strategy for DNS servers, and the telecommunications DNS parsing back to an IP of a telecommunications CDN, and connected DNS returning to an IP of the connected CDN. If users choose a telecommunications export at the time of authentication, but the end equipment DNS settings still point to public DNSs built by their schools, the DNS deconstructing results may not be the best node for telecommunications, leading to a lack of access experience and actual exports. The solution is to distribute the DNS corresponding address according to the operator selected by the user during the DHCP release phase, or to act as a DNS transparency agent on BRAS, and to forcibly forward the user's DNS request to the counterpart operator's relay DNS server. Either approach requires networking between networks, systems and certifications, with communication costs not low.
The billing is another complication. Multi-operator exports mean that the settlement of the bill requires a tripartite reconciliation——The cost models of the different operators are different: flow-based, time- and long-term, and package-month, plus extra speed. Certification systems need to support separate fees based on export strategies. For example, users select a telecommunications export; the traffic generated through VRFs is measured by telecommunications, while the traffic from access to the school resource pool and free addresses of educational networks should not be counted as a package for operators. This requires BRAS to have the ability to account for target-based address-based countervailing capabilities, distinguishing between "fee flows" and "free traffic" in the RADIUS Report. Further, if users visit both in-school and offline resources, the flow of the same user needs to be split into two separate paths at a billing level, which is much more complex than technically speaking.
The private connection and account sharing are particularly sensitive in multi-operability business environments. Operators use the actual number of users and school clearing bandwidth costs. If a large number of students access through shared accounts, operators actually carry far more than contracted users, export bandwidth is squeezed, and complaints and disputes follow.——TTL value detection, UA diversity analysis and simultaneous IP limit——Some systems also complement judgement by combining the DPI in-depth package tests, such as detection of different account IDs with multiple instantaneous communication software under one account number and are largely recognized as sharing. But DPI deployment and maintenance costs are high, and they involve user privacy boundaries, requiring a balance between technology and compliance.
The model itself is evolving. Early multi-export programs were schools renting their own operators bandwidth and then reselling it to students, who took full risk of doing the bandwidth business.——The purchase of bandwidth is not spent on a lossable amount, which exceeds the operator’s speed limit. A model of operator-led investment was then developed whereby operators directly invest in campus network access equipment and are responsible for bandwidth operations, with schools providing space and user resources, divided proportionally. The certification system under this mode needs to support the proxy function at the operator’s side, that is, users certified on school Portal, but actual PPP sessions end up on the operator BRAS. This places higher demands on the interface capacity of the certification system.——To connect to the AAAA, Telecommunication AAAA, connection AAAA and move AAA backstages, the domain retransmission logic of the RADIAS message must be accurate and, once it has been sent to the wrong AAAA, users may be wrongly rejected or wrongly released.
The other scenario is the integrated package. Operators pack and sell school broadband and cellular card packages, and students deliver cellular cards to their dorms.——This real-time query has a hard requirement for the reliability and speed of response to interfaces. Once the search is over, user authentication is blocked on the login page, which experience extreme disadvantages. In practice, a cache plus step compensation strategy is used: first release the user by cache data, backstage off steps to the operator system for updates on the setup status if an anomaly is found to trigger a break or limit.
Multi-operator certification and billing do not technically have insurmountable thresholds, and the real challenge is coordination. Schools, operators, and certification manufacturers have a variety of concerns and interests, and programme design stages are constrained if not fully aligned.
(approximately 1810)