MPLS Packet Forwarding and Label Switched Paths
Each packet enters an MPLS network at an ingress LSR and exits the MPLS network at an egress LSR. This mechanism creates what is known as an Label Switched Path (LSP), which essentially describes the set of LSRs through which a labeled packet must traverse to reach the egress LSR for a particular FEC. This LSP is unidirectional, which means that a different LSP is used for return traffic from a particular FEC. Figure C-5 MPLS Label Imposition and Forwarding The..
Independent Forwarding and Control
With conventional IP packet forwarding, any change in the information that controls the forwarding of packets is communicated to all devices within the routing domain. This change always involves a period of convergence within the forwarding algorithm. A mechanism that can change how a packet is forwarded, without affecting other devices within the network, certainly is desirable. To implement such a mechanism, forwarding devices (routers) should not rely on IP header infor..
CBWFQ Basic Features and Configuration
The CBWFQ scheduler guarantees a minimum percentage of a link’s bandwidth to each class/queue. If all queues have a large number packets, each queue gets the percentage bandwidth implied by the configuration. However, if some queues are empty and do not need their bandwidth for a short period, the bandwidth is proportionally allocated across the other classes. (Cisco does not publish the details of how CBWFQ achieves these functions.) Table 15-5 summarizes some of the key ..
Standard and extended access lists filter IP traffic. An access list is basically a set of permit or deny statements. Standard access lists control IP traffic based on the source address only. Extended access lists can filter on source and destination addresses. Extended access lists can also filter on specific protocols and port numbers. This section covers how a Cisco router handles access lists. Access Lists on Cisco Routers By default, a Cisco router permits all IP and ..
Controlling Multicast Scope with Administratively Scoped Addressing
To configure regions of multicast scope using addressing rather than TTL, using the ip multicast boundary interface command: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#ip multicast-routing Router1(config)#access-list 15 deny 239.255.0.0 0.0.255.255 Router1(config)#access-list 15 permit any Router1(config)#interface FastEthernet0/0 Router1(config-if)#ip multicast boundary 15 Router1(config-if)#end Rout..
