Process Switching, Fast Switching, and Cisco Express Forwarding
Steps 3 and 4 from the generic routing logic shown in the preceding section are the most computation-intensive tasks in the routing process. A router must find the best route to use for every packet, requiring some form of table lookup of routing information. Also, a new Data Link header and trailer must be created, and the information to put in the header (like the destination Data Link address) must be found in another table. Cisco has created several different methods to o..
NLSP is a link state interior gateway protocol for IPX networks. NLSP, which is based on the OSI Intermediate System-to-Intermediate System (IS-IS) protocol, has features similar to those of other link state protocols, such as OSPF. Like other link state protocols, NLSP supports hierarchical addressing and fast convergence. NLSP has the capability to use hierarchical routing techniques to aggregate and summarize IPX network numbers. Route aggregation and summarization are us..
Pure Point-to-Point NBMA Networks
The pure point-to-point network is the simplest of all the setups, and it allows maximum control over the network. Each point -to-point subinterface can be configured to maintain a separate bandwidth, if each VC has a separate capacity. Again, recall the three basic rules: Enhanced IGRP traffic should not exceed the capacity of the virtual circuit. Total Enhanced IGRP traffic for all the virtual circuits cannot exceed the actual line speed. Bandwidth configured for Enha..
Each router participating in the GLBP group can become an AVF, if the AVG assigns it that role, along with a virtual MAC address. The virtual MAC addresses always have the form 0007.b4xx.xxyy. The 16-bit value denoted by xx.xx represents six zero bits followed by a 10-bit GLBP group number. The 8-bit yy value is the virtual forwarder number. By default, GLBP uses the periodic hello messages to detect AVF failures, too. Each router within a GLBP group must send hellos to ever..
InterVLAN routing first requires that routing be enabled for the Layer 3 protocol. In the case of IP, you would enable IP routing. In addition, you must configure static routes or a dynamic routing protocol. These topics are covered fully in the CCNP ROUTE course. By default, every switch port on most Catalyst switch platforms is a Layer 2 interface, whereas every switch port on a Catalyst 6500 is a Layer 3 interface. If an interface needs to operate in a different mode, you ..
