CCNA学习资料.ppt

Slide 1 of 1 Purpose: Emphasize: Slide 2 of 2 Purpose: Emphasize: Layer 2—Adds the general form of the interface command. This links the previously specified interface to a group that will handle its packet for the protocol in the manner specified by the global access list statements. It can help student understanding to learn a generalized command as a simplified template common to most access list processes. However, the details for specific access lists vary widely. As you present the global access list command material that follows in this chapter, return to the template term “test conditions” if it helps your students associate variations to the general elements of this model. Emphasize that “test conditions” is an abstraction for this course. Use this abstraction as a generalization to assist teaching and learning. The words “test conditions” are not a Cisco IOS argument or parameter. Cisco IOS software also offers many variations for the second interface command. As you present these variations, refer your students to the template term “access group” and emphasize how each variation performs a link of the access list test conditions met and the interfaces that packets can use as a result. Slide 1 of 2 Purpose: Emphasize: Introduce the wildcard bit process. Tell students the wildcard bit matching process is different than the IP subnet addressing mask covered earlier. This graphic describes the binary wildcard masking process. Illustrate how wildcard masking works using the examples shown in the graphic table. The term wildcard masking is a nickname for this access list mask-bit-matching process. This nickname comes from an analogy of a wildcard that matches any other card in a poker game. Emphasize the contrast between wildcard masks and subnet masks stated in the student guide note. The confusion over wildcard and subnet masks can be a key obstacle to learning if students fail to understand the different uses of binary 0 and binary 1 in the t