Each router creates and floods a type 1 LSA for itself. These LSAs describe the router, its interfaces (in that area), and a list of neighboring routers (in that area) on each interface. The LSA itself is identified by a link-state ID (LSID) equal to that router’s RID. Type 2 LSAs represent a transit subnet for which a DR has been elected. The LSID is the RID of the DR on that subnet. Note that type 2 LSAs are not created for subnets on which no DR has been elected. Armed ..
OSPF runs on several media types. On some media, such as multiaccess and point-to-point media, the OSPF default network type is used. Therefore, there is no need to configure any network type on those media. This section goes into detail on each medium type in OSPF and what network type to use for each medium. For OSPF, media can be divided into four categories: • Multiaccess media • Point-to-point media • Nonbroadcast multiaccess media • Dema..
Managing Distribution of Multicast Traffic with IGMP
Refer to Figure 19-4. Assume that R2 has started receiving multicast traffic from the server. R2 has to make a decision about forwarding this traffic on the Ethernet links. R2 needs to know the answers to the following questions: ■ Is there any host connected to any of my Ethernet links that has shown interest in receiving this traffic? ■ If none of the hosts has shown any interest in receiving this traffic, why should I forward it on the Ethernet links and waste bandw..
Now plan a road trip from Chicago to San Jose. Assume you have just moved to Chicago, you are not yet familiar with the area, and you need help getting out of the city. Before you plan your route, you first need to know where you are going and where you are coming from. Does that sound familiar? This is not unlike using the source and destination addresses in your postal system. Certainly to begin planning the route, you must know where you are starting; but after you begin t..
The router will keep NAT entries in the translation table for a configurable length of time. For TCP connections, the default timeout period is 86,400 seconds, or 24 hours. Because UDP is not connection based, the default timeout period is much shorteronly 300 seconds, or 5 minutes. The router will remove translation table entries for DNS queries after only 60 seconds. You can adjust these parameters using the ip nat translation command, which accepts arguments in seconds: ..
