When a router is configured as an ABR, it generates summary LSAs and floods them into the backbone area. Adjacencies within an area are advertised using Type 1 or Type 2 LSAs, and these prefixes are passed to the backbone using Type 3 summaries. These summaries are then injected by other ABRs into their own areas (except for totally stubby areas). External routes and summaries from other areas are received by the ABR and passed back into the local area. The flow and pr..
Single-Rate, Three-Color Policer (Two Buckets)
When you want the policer to police at a particular rate, but to also support a Be, the policer uses two token buckets. It also uses all three categories for packets—conform, exceed, and violate. Combining those concepts together, such policing is typically called single-rate, three-color policing. As before, CB Policing fills the buckets in reaction to packet arrival. (For lack of a better set of terms, this discussions calls the first bucket the Bc bucket, because it is ..
Virtual Private Dial-Up Networks (VPDN)
A VPDN is a network that extends remote access dialup clients to a private network. VPDN tunnels use either Layer 2 forwarding (L2F) or Layer 2 Tunnel Protocol (L2TP). Cisco introduced L2F in RFC 2341. It is also used to forward PPP sessions for Multichassis Multilink PPP. L2TP, introduced in RFC 2661, combines the best of the Cisco L2F protocol and Microsoft Point-to-Point Tunneling Protocol (PPTP). Moreover, L2F supports only dial-in VPDN, while L2TP supports both dial-in..
Viewing OSPF Status with Domain Names
You can configure OSPF to resolve IP addresses into router names with the following global configuration command: Router3#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router3(config)#ip ospf name-lookup Router3(config)#end Router3# When you configure OSPF name-lookup, the router will use its locally configured host table, if it has one, or DNS to resolve the names. If both are present, the router will check the local host table fir..
Differences Between Frame Relay Traffic Shaping and Generic Traffic Shaping
This section explains the differences between generic traffic shaping and Frame Relay Traffic Shaping. Generic traffic shaping shapes traffic by reducing outbound traffic flow to avoid congestion. Generic traffic shaping is applied on a per-interface basis, and access lists can be used to selectively filter the type of traffic to shape. Generic traffic shaping works with Frame Relay, ATM, Switched Multimegabit Data Service (SMDS), and Ethernet. Both generic traffic shaping an..
