200-301 official cert guide volume 2

200-301 official cert guide volume 2.The ping command that works in Example 4-2 also requires a data link and valid physical layer detail information. The serial link must also be valid: the router interface must be up/up, indicating that the link can transmit data. On the LAN, R2's LAN interface must be up/up. In addition, since the ping command needs to confirm that packets can be transmitted through R1 to host B and back, anything related to the Ethernet LAN should be valid. In particular, the following are the cases.The switch interface in use is in the up/up connection state.. Port security will not filter out frames sent by R2 or Host B.STP has put the correct port in the forwarding state.Tip: This diagram shows a smaller LAN with only one switch,For larger LANs with numerous switches. a valid ping command can confirm that STP has indeed converged to a valid topology. "The ping 172.16.2.101 in Example 4-2 also confirms that the IP access control list (ACL) is not filtering out ICMP messages. As a hint, ACLs on routers do not filter packets created on the same router, so R1 does not filter its own ICMP response request messages. Other ICMP messages are already filtered in or out of the router's interface. Figure 4-9 shows where the IPACL filters messages generated by R1's ping172.16.2.101 command.Figure 4-9 Location of IPACL filtering ping messages4.2 Base Content 95Finally, the ping 172.16.2.101 working on R1 can also be used to reasonably predict that ARP is working on R2 and Host B, and that Switch SW2 has been informed of the address of its MAC address table.R2 and Host B need to know each other's MAC addresses in order to encapsulate IP packets in Ethernet frames, which means that both must have matching ARP table entries. When sending an ARP message or sending a frame with an IP packet, the switch knows the MAC addresses used by the circle and Host B. Figure 4-10 shows the types of information that might be present in these tables.giit R2ARP table abundance machine BARP table next point [iPittk________ MAC Lantau __________ IP Lantau MAC Mtlt 172.16.2.101 0200.2222.2222