January 2002
Beginner
238 pages
6h 20m
English
Content preview from IP Routing
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
NBMA Networks
Remember how a DR is elected -- basic to DR election is the broadcast or multicast capability of the underlying network. NBMA networks such as Frame Relay or X.25 have no inherent broadcast or multicast capability, but they can simulate a broadcast network if fully meshed. However, a fully meshed network with n nodes requires n x (n-1)/2 virtual circuits. The cost of n x (n-1)/2 virtual circuits may be unpalatable, and besides, the failure of a single virtual circuit would disrupt this full mesh.
One option around a fully meshed network is to (statically) configure the DR for the network. The DR will then advertise the NBMA network as a multi-access network using a single IP subnet in a network LSA.
Another option is to configure the network as a set of point-to-point networks. This is simpler to configure, manage, and understand. However, each point-to-point network wastes an IP subnet. So what? You can use VLSM in OSPF, with a two-bit subnet for each point-to-point network. That is a good argument. However, the trade-off is the processing overhead of an LSA for each point-to-point network.
Let’s look at examples of each of these options.
NewYork2 is set up with a serial interface to support Frame Relay PVCs to offices in Miami and New Orleans, as shown in Figure 6-12.
Figure 6-12. TraderMary’s Frame Relay network
The command ip ospf network broadcast (lines 52, 53, and ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.