# A Survey on Efforts to Evolve the Control Plane of Inter-Domain Routing
## 2 Related Surveys  
This section depicts the scope of this survey, as well as the related surveys on approaches to change the inter-domain routing control plane. Table 1 compiles the major surveys related to this work. The main idea here is to explain how this survey is different and complements other related surveys to provide a more understandable and comprehensive state-of-the-art revision for the control plane of inter-domain routing. First, currently, the inter-domain routing control plane of the Internet is distributed through different ASs and embedded into the router devices. In general, the control plane of the device is anything that is necessary in order to make all the network protocols work. This includes the drivers for each network interface, as well as the Network Operational System (NOS). Specifically, the BGP control plane is the software responsible for establishing a connection to other BGP devices, creating the inter-domain high-level topology, computing paths to reachable networks and applying filters and advertise routes to allow other networks to share the global state of this AS-level topology and connectivity. Because the BGP is currently the main inter-domain routing protocol, it is natural to assign the control plane of the BGP as the control plane of the Internet itself. However, this statement \begin{table}
\begin{tabular}{c c} \hline \hline
**Proposal and Authors** & **Main Focus** \\ \hline [PERSON] et al. [19] & Issues in inter-domain routing \\ [PERSON] and [PERSON] [22] & BGP convergence \\ [PERSON] et al. [17] & BGP security \\ [PERSON], [PERSON] and [PERSON] [15] & Multipath routing and provisioning \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Compilation of related surveys. BGP, Border Gateway Protocol. does not hold, since there are other inter-domain routing protocols also composing the Internet. For example, a domain that uses the Path Computation Element (PCE) architecture can use Resource Reservation Protocol (RSVP-Traffic Engineering (TE)) to exchange inter-domain routing information between domains [23]. Furthermore, this survey will not cover obsolete protocols for inter-domain routing, such as the Exterior Gateway Protocol (EGP) [24] and Inter-Domain Routing Protocol (IDRP) [25]. Although those protocols share fundamental properties with the BGP [26], e.g., distributed path selection computation and the control plane embedded into network appliances, they never reach the wide deployment and the success of the BGP. Thereby, it is worth restricting the scope of this survey to tackle the approaches to evolve the control plane of inter-domain routing with special attention to BGP and also \"clean-slate\" architecture designs and innovative technologies. Regarding related surveys, [PERSON] et al. [19] organized and presented several distinct issues on inter-domain routing works, where for each issue description, one main effort was presented to resolve it. The authors considered multi-homing scalability issues, lack of multipath routing, limited traffic engineering capabilities, convergence time, and others. The majority of those issues still remain open, and one of the reasons for that is the currently widely-deployed Version 4 of the BGP (defined in 2006 [6]) embedded into network appliances. Hence, the addition of new capabilities, functionalities or modification of the BGP often takes years from the first draft specification until it reaches the production environment. This difficult and long process of making changes in inter-domain routing with the BGP is called \"ossification\" of the protocol, and it is depicted in Section 4.1. [PERSON] and [PERSON] [22] focused on the long convergence time required by the BGP. They presented a good and detailed survey about approaches to reduce the delay of the BGP inter-domain routing convergence on the Internet.