MLS Configuration

The upcoming MLS configuration example is designed to show all of the configuration options. The network design is shown in Figures 7-4 and 7-5. In Figure 7-4, the physical topology is shown, with routed ports, VLAN trunks, a routed PortChannel, and access links. Figure 7-5 shows the same network, with a Layer 3 view of the subnets used in the network. Figure 7-4 Physical Topology: Example Using MLS   Figure 7-5 Layer 3 Topology View: Example Using MLS   A few de..

Using IS-IS Pseudonode

Instead of treating a broadcast network as a fully connected topology, IS-IS treats a broadcast network as a pseudonode with links to each attached system.   NOTE   To reduce the number of full mesh adjacencies between nodes, multiaccess links are modeled as pseudonodes. As the name implies, this is a virtual node. One of the ISs on the link is designated to be the pseudonode; this node is called the designated intermediate system (DIS). All routers on..

Multicast Addresses for GLOP Addressing

IANA has reserved the range 233.0.0.0 through 233.255.255.255 (RFC 2770), called GLOP addressing, on an experimental basis. It can be used by anyone who owns a registered autonomous system number (ASN) to create 256 global multicast addresses that can be owned and used by the entity. IANA reserves addresses to ensure global uniqueness of addresses; for similar reasons, each autonomous system should be using an assigned unique ASN. By using a value of 233 for the first octet,..

Using HSRP on Token Ring

You can use HSRP on a Token Ring LAN exactly the same if the only protocol on the segment is IP. However, if you have any other protocols, and particularly if the ring uses any source-route bridging, you must use a slightly different configuration: Router1#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. Router1(config)#interface Tokenring0 Router1(config-if)#ip address 172.22.1.3 Router1(config-if)#standby ip 172.22.1.1 Router1(con..

Filtering Based on Noncontiguous Ports

To filter noncontiguous ports, use the following commands: Router2#configure terminal Enter configuration commands, one per line.  End with CNTL/Z.Router2(config)#ip access-list extended OREILLYRouter2(config-ext-nacl)#permit tcp any host 172.25.100.100 eq 80 23 25 110 514 21Router2(config-ext-nacl)#endRouter2#   Cisco introduced the ability to filter noncontiguous ports in IOS Version 12.3(7)T.   Historically, Ci..