The weight, more fully titled administrative weight, allows a single router to examine inbound BGP Updates and decide which routes to prefer. The weight is not a BGP PA, but simply a Ciscoproprietary setting on a local router. In fact, it cannot be included in a BGP Update sent to another router, because there is no place in the Update message to include the weight. Table 13-10 summarizes the key points regarding BGP weight. Table 13-10 Key Features of Administrative Weight ..
NEXT_HOP Behavior Over Nonbroadcast Multiaccess Media
Media such as Frame Relay and ATM are referred to as nonbroadcast multiaccess media. Themany-to-many direct interaction between routers is not guaranteed unless virtual circuits areconfigured from each router to all other routers. This is referred to as a full-mesh topology,and it is not always implemented for a number of reasons. In practice, Frame Relay or ATMvirtual circuits are provided by the access carrier at a certain dollar amount per circuit, andadditional circuits t..
MPLS Packet Forwarding and Label Switched Paths
Each packet enters an MPLS network at an ingress LSR and exits the MPLS network at an egress LSR. This mechanism creates what is known as an Label Switched Path (LSP), which essentially describes the set of LSRs through which a labeled packet must traverse to reach the egress LSR for a particular FEC. This LSP is unidirectional, which means that a different LSP is used for return traffic from a particular FEC. Figure C-5 MPLS Label Imposition and Forwarding The..
WFQ requires very little configuration—in fact, it is on by default on E1-and-slower serial links. So, with default settings, WFQ literally requires no configuration commands. Table 15-4 lists the commands related to WFQ. Of particular importance, note that the fair-queue command allows setting of the CDT, number of queues, and number of RSVP queues, and the hold-queue command sets the number of packets allowed in all queues on the interface. Table 15-4 Command Reference ..
So far in this section, the database exchange process has focused on exchanging the database between neighbors. However, LSAs need to be flooded throughout an area. To do so, when a router learns new LSAs from one neighbor, that router then knows that its other neighbors in that same area may not know of that LSA. Similarly, when an LSA changes, for example, when an interface changes state, a router may learn the same old LSA but with a new sequence number, and again need to ..
