tailieunhanh - CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 90

Cisco Networking Academy Program CCNA 1 and 2 Companion Guide, Revised part 90 is the Cisco approved textbook to use alongside version of the Cisco Networking Academy Program CCNA 1 and CCNA 2 web-based courses. The topics covered provide you with the necessary knowledge to begin your preparation for the CCNA certification exam (640-801, or 640-821 and 640-811) and to enter the field of network administration. | Page 859 Tuesday May 20 2003 2 53 PM Extended ACLs 859 Table 20-3 Extended ACL Parameters Continued Parameter Description log The message includes the access list number whether the packet was permitted or denied the protocol whether it was TCP UDP ICMP or a number and if appropriate the source and destination addresses and source and destination port numbers. By default the message is generated for the first packet that matches and then at five-minute intervals including the number of packets permitted or denied in the previous five-minute interval. Use the ip access-list log-update command to generate logging messages when the number of matches reaches a configurable threshold instead of waiting for a 5-minute interval . See the ip access-list logupdate command for more information. The logging facility might drop some logging message packets if there are too many to be handled or if there is more than one logging message to be handled in one second. This behavior prevents the router from crashing because of too many logging packets. Therefore the logging facility should not be used as a billing tool or an accurate source of the number of matches to an access list. log-input Optional Includes the input interface and source MAC address or VC in the logging output. time-range time-range-name Optional Name of the time range that applies to this statement. The name of the time range and its restrictions are specified by the time-range command. icmp-type Optional ICMP packets can be filtered by ICMP message type. The type is a number from 0 to 255. icmp-code Optional ICMP packets that are filtered by ICMP message type also can be filtered by the ICMP message code. The code is a number from 0 to 255. icmp-message Optional ICMP packets can be filtered by an ICMP message type name or ICMP message type and code name. continues Page 860 Tuesday May 20 2003 2 53 PM 860 Chapter 20 Access Control Lists Table 20-3 Extended ACL Parameters Continued Parameter