## 1 Introduction  
The deployment of the 5 th generation mobile networks (5G) will lead to a revolutionary transformation of telecommunication networks [1]. By enabling access to new wireless services, including enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra-reliable and low-latency communications (URLLC), 5G networks will have a profound impact on different aspects of people's activity [2]. Provisioning of these services in 5G networks will require implementation of centralized and virtualized radio access network architectures [3]. In a centralized radio access network (C-RAN), baseband processing of radio frequency (RF) signals, referred to as a baseband unit (BBU), is separated from the base station/antenna site and moved to a central location, at which the BBUs from different sites are supported. Concurrently, in a virtualized radio access network (vRANs), the BBU processing functions are virtualized and performed on general-purpose processors in a cloud environment. 5G C-RANs will require cost-effective solutions in order to assure connectivity between a large number of antenna sites and centralized BBUs in the so-called fronthaul network [4]. Since current fronthaul technologies are not scalable and flexible in a sufficient way to meet the requirements of 5G services, the research community and industry have worked on developing suitable fronthaul solutions for 5G [5; 6]. Among them, the IEEE P1914.1 standard for packet-based fronthaul transport networks [7], which defines the next generation fronthaul interface (NGFI) architecture, is a very most promising one. IEEE has also proposed the IEEE 802.1 CM standard specifying time-sensitive networking (TSN) for packet-switched fronthaul networks [8]. In the IEEE 802.1 CM standard, Ethernet technology supported by deterministic TSN features is considered for fronthaul networks. In this paper, we focus on the network scenario implementing both mentioned IEEE standards, which we refer to as the NGFI network (see Figure 1). In NGFI, the radio frequency processing functions are split and performed in radio (RU), distributed (DU), and central (CU) units. In this architecture, the RUs realize low-level physical functions at the antenna sites, while DUs and CUs perform the BBU functions. The DU and CU entities are virtualized, which allows to perform RF processing on general-purpose processors in a processing pool facility [9]. The radio frequency functions that are time-critical are performed at the DU that is located at a processing pool (PP) node in proximity of the RU. This allows to reduce bandwidth requirements of the traffic carried between the DU and CU, whenever the CU is placed in a different PP node. The radio frequency processing is completed in the CU, from which the resulting IP traffic is sent towards the core network for further 5G core and content processing in a data center. The specification and requirements of the virtualized and centralized (RU-DU-CU) radio access network architecture are currently under development within the open ran (O-RAN) initiative founded by major network operators cooperating in the O-RAN Alliance [10]. In the NGFI architecture, three distinct sections can be distinguished, namely fronthaul (FH), midhaul (MH), and backhaul (BH). Fronthaul is the part of the network between the RU and DU, midhaul spans from DU to CU, and backhaul is between the CU and a data center (DC). In the NGFI scenario considered, the data between the RUs, DUs, CUs, and data centers are encapsulated and transmitted as Ethernet frames (packets)--in this paper, terms packet and frame are used interchangeably. The NGFI network allows for convergent transport of different types of flows, including FH, MH, and BH flows, over a shared network. The frames belonging to particular data flows are switched using Ethernet switches (bridges) and routed over a common packet-switched  
Figure 1: 5G network implementing packet-switched next generation fronthaul interface (NGFI) network architecture.