Example of OSPF Network Types and NBMA
On NBMA networks with an OSPF network type that requires that a DR be elected, you must take care to make sure the correct DR is elected. The reason is that the DR and BDR must each have a PVC connecting it to all the DROther routers—otherwise, LSA flooding will not be possible. So, with partial meshes, the election should be influenced by configuring the routers’ priority and RIDs such that the hub site of a hub-and-spoke partial mesh becomes the DR. Figure 10-3 shows an..
This section concludes the coverage of PIM-DM. Table 20-2 lists the key PIM-DM messages covered in this chapter, along with a brief definition of their use. Table 20-2 Summary of PIM-DM Messages The next two short sections introduce two other dense-mode protocols, DVMRP and MOSPF
Mitigating Detrimental Effects of the LDP Restart
As discussed previously, when the LDP control-plane component of an LSR restarts, it causes the failure of LDP sessions between that LSR and its peers. As soon as a peer detects the failure of an LDP session with the restarting neighbor, that peer immediately terminates the concerned LDP session and releases FEC-to-label mappings and the MPLS forwarding state for all LSPs associated with the failed LDP session. Therefore this control-plane restart behavior results in disrupti..
A variable-length subnet mask (VLSM) is designed to allow greater use of IP address space by borrowing bits from the subnet mask and allocating them to host devices. To allow a greater number of devices to connect to the Internet and intranets, the standards bodies of various routing protocols designed an IP routing algorithm to cater to IP networks with a different subnet mask than the default used in classful networks. Note Routing algorithms that support VLSM are as foll..
With the emergence of voice traffic into data networks, the need to differentiate between the various classes of service has become greater. PQ/CBWFQ, most commonly known as LLQ, is a new feature that provides a strict priority queue for voice traffic and a weighted fair queue for each of the other classes of traffic. LLQ brings strict priority queuing to the CBWFQ scheme. Figure 18-4 illustrates the basic concepts of how LLQ works. Figure 18-4. How LLQ Works Without ..
