FastEther Channel (FEC) is a Cisco method that bundles 100 Mbps FAST ETHERNET ports into a logical link. Because any redundant paths between two switches mean some ports will be in a blocking state and bandwidth will be reduced, Cisco developed FEC to maximize bandwidth use. Figure 2-4 displays a switched network with two 100-Mbps connections between them. Because of STP, the link will be in a blocking state after the election of a root bridge, Switch A, in this case. Switc..
Defining the Router ID and Loopback Interfaces
The router needs an ID to participate in the OSPF domain. The router ID is used to identify LSAs in the OSPF database. The router ID can be defined by an administrator or left to the discretion of the router. Most people define the ID so that it is easier to track events in the network, for internal documentation, and for other system-administration purposes. The OSPF router ID can be defined by the router-id command. If the router-id command is not present, then the ..
Understanding Level 1 and Level 2 Routing
In level 1, IS nodes are based on the ID portion of the address. All level 1 routers route within their own area. They recognize the destination within their area by reading the destination address. If the destination is within the same area, the packet is routed to the destination. If the destination is not within the same area, it is sent to the closest level 2 router. In IS-IS, all level 1 areas are stub areas, so no information is sent to level 1 routers tha..
Multicast Addresses for Permanent Groups
IANA has reserved two ranges of permanent multicast IP addresses. The main distinction between these two ranges of addresses is that the first range is used for packets that should not be forwarded by routers, and the second group is used when packets should be forwarded by routers. The range of addresses used for local (not routed) purposes is 224.0.0.0 through 224.0.0.255. These addresses should be somewhat familiar from the routing protocol discussions earlier in the boo..
MPLS Nonstop Forwarding Architecture
MPLS control-plane SSO requires two instances (active and standby) of IP routing protocols and label-distribution protocols. The active instances reside on the active control processor that controls the system. The standby instance resides on the standby control processor that maintains state for the stateful components and waits to become active following a control-plane switchover. The active instances of IP routing protocols and label-distribution protocols establish sessi..
