Mnemonics for Memorizing the Decision Process
Many people do not bother to memorize the BGP decision process steps. However, memorizing the list is very useful for both the CCIE Routing Switching written and lab exams. This section provides a set of mnemonic devices to aid you in memorizing the list. Please feel free to learn the mnemonic or skip to the next heading, at your discretion. Table 13-8 BGP Decision Process Mnemonic: N WLLA OMNI The first mnemonic step is to memorize the nine trigger letters—single..
Configuring Bandwidth over a Hybrid Multipoint Network
If the multipoint network has differing speeds allocated to the VCs, a more complex solution is needed. There are two main approaches: • Take the lowest CIR and multiply it by the number of circuits. Apply the product as the bandwidth of the physical interface. The problem with this configuration is that EIGRP will underutilize the higher-bandwidth links. • If possible, it is much easier to configure and manage an environment that has used subinterfaces, whe..
Complete sequence number PDU (CSNP) has a fixed header with TLV appended. Each of these TLVs represents an LSP in the link-state database. The following summary information is carried regarding each LSP: The LSP ID The sequence number The LSP checksum The remaining lifetime CSNP is like a database description packet, as in OSPF. Because IS-IS does not have difficulty with synchronization, as OSPF does, the DIS sends a CSNP every 10 seconds o..
Disabling Link Up/Down Traps per Interface
To disable SNMP link-status change traps for a particular interface, use the following configuration command: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#interface Serial0/0 Router(config-if)#no snmp trap link-status Router(config-if)#exit Router(config)#end Router# By default, the router forwards SNMP link up or down traps whenever an interface changes states. Normally, you want to receive traps when an inter..
Spanning-Tree Communication: Bridge Protocol Data Units
STP operates as switches communicate with one another. Data messages are exchanged in the form of bridge protocol data units (BPDU). A switch sends a BPDU frame out a port, using the unique MAC address of the port itself as a source address. The switch is unaware of the other switches around it, so BPDU frames are sent with a destination address of the well-known STP multicast address 01-80-c2-00-00-00. Two types of BPDU exist: ■ Configuration BPDU, used for spanning-tree..
