The growing demand for IP addresses has put a severe strain on the classful model. Most companies requesting Class B addresses have estimated that a Class B address would best accommodate their requirements because of the balance between the number of networks and the number of hosts. A Class A was overkill, with more than 16 million hosts, and a Class C had too few hosts per network. By 1991, it was becoming obvious that the Class B consumption was not slowing and actions ..
MPLS/VPN Architecture Overview
Virtual private networks (VPNs) have evolved using two major VPN models: overlay VPN and peer-to-peer VPN. The overlay VPN model, most commonly used in a service provider network, dictates that the design and provisioning of virtual circuits across the backbone must be complete prior to any traffic flow. In the case of an IP network, this means that even though the underlying technology is connectionless, it requires a connection-oriented approach to provision the service. F..
External LSA (Link-State Type 5)
External LSA describes destinations outside the OSPF domain. A route received via another routing protocol and redistributed into OSPF is considered external to OSPF. Any destination that is not originated by the local OSPF process is also considered external. Refer to Figure 9-14. Router R7 redistributes 140.10.0.0 into OSPF; 140.10.0.0 was not originated by the local OSPF process. In Figure 9-17, R7's link-state ID field is set to the external destination adve..
The development of routers can be characterized through three generations. The first generation consists of a single CPU controlling relatively unsophisticated line cards through a general- purpose shared I/O bus. Packet queues between line cards are maintained in central or shared memory by the CPU, which coordinates all packet forwarding. In the worst case, packets may traverse the I/O bus twice to complete the forwarding process. A second-generation switch su..
Cisco Router and Security Device Manager
Cisco Router and Security Device Manager (SDM) is an intuitive, secure, web-based embedded device manager of Cisco IOSenabled devices. SDM provides intelligent wizards, detects mis-configured devices, steps security managers through firewall and VPN configurations, and has been certified and recommended by some key organizations within Cisco, such as the Cisco Network Supported Accounts (NSA), a group of expert engineers within Cisco whose services are sold to high-end client..
