Caveats Regarding OSPF Network Types over NBMA Networks
When configuring OSPF over Frame Relay, the OSPF network type concept can become a bit troublesome. In fact, many CCIE Routing and Switching lab preparation texts and lab books focus on the variety of combinations of OSPF network types used with Frame Relay for various interfaces/subinterfaces. The following list contains many of the key items you should check when looking at an OSPF configuration over Frame Relay, when the OSPF network types used on the various routers do no..
The final PIM-DM message covered in this chapter is the PIM Assert message. The Assert message is used to prevent wasted effort when more than one router attaches to the same LAN. Rather than sending multiple copies of each multicast packet onto the LAN, the PIM Assert message allows the routers to negotiate. The winner gets the right to be responsible for forwarding multicasts onto the LAN. Figure 20-12 shows an example of the need for the Assert message. R2 and R3 both atta..
LDP Control-Plane and Forwarding-Plane Components
The state of an LSP that is established through LDP can be divided into two components: the LDP state (which is maintained in the control plane), and the MPLS forwarding state (which is maintained in the forwarding plane). The exact format of the LDP state or the MPLS forwarding state of an LSP in an LSR depends on whether the LSR is ingress, egress, or transit for that LSP. For example, LSP ingress LSR uses a FEC-to-NHLFE (FTN) entry to map the associated FEC to one or more..
A device being managed by SNMP runs a process called an SNMP agent. A Network Management System (NMS) can then query the agent for information, using the SNMP protocol. SNMP version 3 (that is, SNMPv3) supports encryption and authentication of SNMP messages; however, the most popular SNMP version deployed today is SNMPv2c. SNMPv2c uses community strings for security. Specifically, for an NMS to be allowed to read data from a device running an SNMP agent, the NMS must be confi..
OSPF defines an ASBR as a router that redistributes routes into OSPF from some other routing source. When redistributing the routes, the ASBR creates a Type 5 External LSA for each redistributed subnet, listing the subnet number as the LSID and listing the mask as one of the fields in the LSA. The LSA also lists the ASBR’s RID as the advertising router and a cost metric for the route. For the purposes of route summarization, you can think of a Type 5 LSA as working much lik..
