TACACS+ authentication takes place via three distinct packet exchanges between the NAS and the TACACS+ daemon. TACACS+ authentication uses the following three types of packets: START REPLY CONTINUE Authentication starts when the NAS receives a connection request that needs to be authenticated. The NAS at this point sends a START message to the TACACS+ server. This message contains information regarding the type of authentication to be performed. It can also contain furthe..
Routers sharing a common data link layer become IS-IS neighbors if the Hello packets that they exchange meet the criteria for forming an adjacency. Although the process of finding a neighbor differs slightly depending on the media, the information sent in the Hellos is essentially the same. Each Hello states the originator of the Hello and the capabilities of its interface. If the Hellos are exchanged and the criteria are met, an adjacency is formed and the Integrated I..
When building a wireless LAN based on Cisco SWAN, a company must choose components designed to fit into the architecture. Cisco SWAN includes the components described in Table 23-2. Table 23-2 Cisco SWAN Hardware
Currently, IS-IS is being used as an IGP by some of the largest ISPs. In most cases, a well- defined ISP network should not have a large IGP routing table, but due to extensive redundancy, scaling does become a problem. In addition, even if the IGP has a strong addressing structure, sometimes it must find specific routes to the next hop according to strict policy requirements. For this reason, route summarization is not always possible. Experience in working wit..
This section illustrates the operation of the Cisco IS-IS restart mechanism, using the network diagram shown in Figure 5-8. Both R1 and R2 are Cisco IS-IS restart/NSF-capable and are interconnected via point-to-point links. • Assume using normal IS-IS procedures, R1 and R2 have synchronized their databases and are ready for forwarding. Suppose a forwarding path exists from "source" to "destination" passing through R1 and R2, and data traffic is being forw..
