FTP clients and servers use the typical TCP/IP client/server model for the FTP control connection, with the client initiating a TCP connection to well-known FTP port 21. FTP transfers commands and command acknowledgements over the this TCP control connection. However, at some point, data needs to be transferred—and FTP uses a separate but correlated TCP connection for the actual data transfer. FTP clients use one of two modes, passive or active, to define the details of ho..
The point-to-multipoint model is very similar to the point-to-point model. It provides one subnet for an entire cloud, and it maintains host routes to all the routers within the cloud. This also allows the use of non-meshed routers. TIP A new command was recently introduced to overcome the problem of sending multicast OSPF packets on the media that form dynamic connections, such as ATM SVC. By default, OSPF sends multicast packets to discover neigh..
Enhanced IGRP can simultaneously use unequal cost paths to the same destination, which indicates that traffic can be distributed among multiple (up to four, by default) unequal cost paths to provide greater overall throughput and reliability. An alternate path is used if the variance condition is met. The variance condition depends on two factors: The local metric must be greater than the metric of the next router, so the next hop router must be closer to the destinat..
Using Auto-QoS to Simplify a Configuration
You can also configure Cisco switches to support a variety of other QoS mechanisms and parameters. The list of features and configuration commands can be overwhelming, and the actual configuration can be quite complex. This is one reason why the bulk of QoS topics are no longer covered on the SWITCH exam. Courses and testing aside, you will sometimes need to configure some advanced QoS features on a switch. To reduce the complexity, Cisco introduced the Auto-QoS feature on m..
As an example of trunk configuration, consider two switches, Switch D and Switch A, which are distribution-layer and access-layer switches, respectively. The two switches are connected by a link between their Gigabit Ethernet 2/1 interfaces. This link should be configured to be a trunk carrying only VLAN numbers 100 through 105, although more VLANs exist and are used. The trunk link should use 802.1Q encapsulation, with VLAN 100 as the native VLAN. First, configure Switch-D t..
