# A Versatile Resilience Packet Ring Protocol Model for Homogeneous Networks
## 2 Related Work
### Route Failure and Spectrum Mobility  
In this subsection, we discuss various types of route failures due to different handovers. The appearance of a Mobile Node (MN) in a wireless active channel or node mobility usually results in spectrum mobility. This spectrum mobility is available to various non-interferingchannels inside the same spectrum band (intra-spectrum switching) or another type of spectrum band (inter-spectrum switching). _WN Co-ordinate Message Update = True; //control channel Neighbor discovery (Channel + Route) = True;_  
_Case 1. If (Route Failure = WN Node Mobility) Step 1 : if (TTL < Local Channel-route Re-construction Time) Local Channel-route Re-construction= True; Next hop= route + new channel selection; Control channel Spectrum mobility= True; Else Step 2: Local Channel-route Re-construction = False;_  
_Global re-route = True; New route = RREQ + RREP (Path +Channel) Control Channel Spectrum mobility = True Case 2. If (Route Failure == MN Appearances) CR current channel allocate = False; If (Spare channel-path for next hop WN == True) Re-route = False; // Use spare Channel-path to next hop Spectrum mobility = True;_  
_If (spare channel-path for next hop WN == False) if (TTL < Local channel-route Re-construction time) go to step 1 else go to step 2._  
Different types of Layers 2 handover delay factors are depicted in Table 1. There are two main types: mobile IP and protocols for micro-mobility support. In a network-layer handover, while moving from one Access Point (AP) to another AP, the IP address of the MN is changed [14; 15; 16]. This happens due to the mobile IP technique. Mobile IP is used for IPv4 (RFC 3344) and IPv6 (RFC 5944). In mobile IP, it uses two IP addresses: the home address and care-of address. When one MN moves from its home node to another node, it has one tunnel between the MN and the home link. In micro-mobility support, there are two types of methods. The first one is tunnel-based, and the second is routing-based. First, for the tunnel-based Hierarchical Mobile IP (HMIP), the Intra-Domain Mobility Management Protocol (IDMP) proposes a packet redirect technique inside a domain using a hierarchical mobile agent. Secondly, the routing-based Cellular IP (CIP) and Handoff-Aware Wireless Access Internet Infrastructure (HAWAII) use cross-layer techniques to generate paths to mobile nodes moving among access points. Table 2 shows the delay of handover. This technology focuses on 3 GPP, 802.21, UMA, and IMS. The essential method is IEEE 802.21, which is called MIH; its functionality is now widely adopted in different applications [9]. We will discuss this technology in detail in the next s \begin{table}
\begin{tabular}{c c} \hline
**Item** & **Time (ms)** \\ \hline
802.11 scan (passive) & 1000 (wait for beacon) \\
802.11 scan (active) & 40 to 300 \\
802.11 associate/re-associate & 2 \\
802.11 associate/re-associate & 1000 \\
802.1X authentication (fast resume) & 250 \\ Fast handover (4-way handshake only) & 60 \\ \hline \end{tabular}
\end{table} 
Table 1: Layer 2 handover delay [15]. \begin{table}
\begin{tabular}{c c} \hline
**Item** & **Time (ms)** \\ \hline Initial Router Solicitation (RS)/Router Advertisement (RA) & 5 \\ Wait for subsequent RA & 1500 \\ DHCPv4 & 1000 \\ Duplicate Address Detection (DAD) & 1000 \\ Optimistic DAD & 0 \\ MN-HA Binding Update & RTT(HA SA), 4 RTT (CoA SA) \\ MN-CN Binding Update & 2.5 RTT (RR) \\ \hline \end{tabular}
\end{table} 
Table 2: Layer 3 handover delay [15]. occurs in a different network, then it is called a heterogeneous (vertical) handover. Vertical handover is closer to our topic. In this process, one cell transfers its session to another network. It may be a wireless or wired network. There are different types of handovers; e.g., in a link-layer handover (802.11 and 802.11r), the MN moves from one AP to another AP in the same subnet. The IP address remains the same, so the outer AP does not know about this change, and communication goes in the link-layer protocol.