An IPv6 anycast address is a global unicast address that is assigned to two or more devices. Other devices route to the closest active device with the anycast address; the routing protocol metric determines which is closest. Figure 20-5 shows an example network topology from which there are two connections to an ISP. Both border routers have been configured with the same IPv6 anycast address; the internal routers simply route the client to the closest one (Route..
For various reasons, switching performance being one, the MPLS label must be inserted in front of the labeled data in a frame-mode implementation of the MPLS architecture. The MPLS label thus is inserted between the Layer 2 header and the Layer 3 contents of the Layer 2 frame, as displayed in Figure C-11. Figure C-11 Position of the MPLS Label in a Layer 2 Frame Due to the way an MPLS label is inserted between the Layer 3 packet and the Layer 2 header, the MPLS label..
Bridges, operating at a layer higher than repeaters, add functionality to the network, which is not present in repeaters. Bridges perform all repeater functions, and more, by creating new collision domains. Likewise, routers, which operate at Layer 3, add functionality beyond bridges. Routers extend networks like bridges, but they create both collision and broadcast domains. Routers prevent broadcasts from propagating across networks. This broadcast isolation creates individu..
We should start by stressing that the Secure Socket Layer (SSL) WebVPN options available on an IOS router are severely limited compared to those available on dedicated VPN concentrator devices, such as the Cisco VPN 3000 series devices. In particular, the IOS version of WebVPN only supports SSL Version 3, and not Transport Layer Security (TLS), it doesn't support Cisco Security Desktop (CSD) or Cisco SSL VPN Client software, and it doesn't support Macromedia Flash URLs. On t..
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 ..
