CIDR, Private Addresses, and NAT
The sky was falling in the early 1990s in that the commercialization of the Internet was rapidly depleting the IP Version 4 address space. Also, Internet routers’ routing tables were doubling annually (at least). Without some changes, the incredible growth of the Internet in the 1990s would have been stifled. To solve the problems associated with this rapid growth, several short-term solutions were created, as well as an ultimate long-term solution. The short-term solution..
Overriding the Defaults for Login Security
The console, vty, and aux (routers only) lines can override the use of the default login authentication methods. To do so, in line configuration mode, the login authentication name command is used to point to a named set of configuration methods. Example 21-6 shows a named group of configuration methods called for-console, for-vty, and for-aux, with each applied to the related login method. Each of the named groups defines a different set of authentication methods. Example 2..
Making Interface Table Numbers Permanent
To ensure that SNMP interface numbers remain permanent after a router power cycle, use the following command. This is a global command that affects all interfaces: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#snmp-server ifindex persist Router(config)#end Router# You can also fix the SNMP interface number of a single interface as follows: Router#configure terminal Enter configuration commands, one per line. ..
Multicast over Frame Relay or ATM WANs
When using PIM-SM on an nonbroadcast multiple access (NBMA) network, such as a Frame Relay or ATM WAN, you must configure the ip pim nbma-mode interface command: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#ip multicast-routing Router1(config)#interface Serial0/0 Router1(config-if)#encapsulation frame-relay Router1(config-if)#ip pim sparse-mode Router1(config-if)#ip pim nbma-mode Router1(config-if)#end ..
End-to-end VLANs, also called campuswide VLANs, span the entire switch fabric of a network. They are positioned to support maximum flexibility and mobility of end devices. Users can be assigned to VLANs regardless of their physical location. As a user moves around the campus, that user’s VLAN membership stays the same. This means that each VLAN must be made available at the access layer in every switch block. End-to-end VLANs should group users according to common req..
