Network Certification Preparation

Module - 5 Basic troubleshooting of IP addressing issues Basic troubleshooting of RIP and IGRP Basic troubleshooting of switched networks, VLANs etc Understanding access control lists and its types Configure and troubleshoot ACL issues

Basic troubleshooting of IP addressing issues Check the same subnet or network Check if it is valid IP address Verify the IP address configured is the correct one Use troubleshooting commands i.e. show ip interface brief Use ping utility Check if ARP is resolved

Basic troubleshooting of RIP and IGRP Verify if the required networks are advertised in routing protocols. For RIP the max hop count is 15, otherwise the route is unreachable and ping/traffic will fail. Make sure no route filtering is enabled Interface is not down where routes are supposedly advertised/received. Interface is passive interface hence not advertising.

ACL – Access Control List ACL is a list of permissions or denial attached to an object. An ACL specifies which users or system processes are granted access to objects, as well as what operations are allowed on given objects. Masks are used with IP addresses in IP ACLs to specify what should be permitted and denied. Masks for IP ACLs are the reverse, for example, mask This is sometimes called an inverse mask or a wildcard mask. 0 indicates that the address bits must be considered (exact match); and 1 in the mask is a "don't care". Router#(config)access-list TEST permit ip

ACL – Access Control List Types of ACL Standard ACL Extended ACL Standard ACL: Standard Access Control Lists: Range is from 1 to 99. A Standard Access List allows you to permit or deny traffic FROM specific IP addresses. The destination of the packet and the ports involved can be anything. This is the command syntax format of a standard ACL. access-list access-list-number {permit|deny}{host|source source- wildcard|any} Example: access-list 10 permit show access-list 10 The output looks like: access-list 10 permit access-list 10 deny any

ACL – Access Control List Extended ACL Allows you to permit or deny traffic from specific IP addresses to a specific destination IP address and port. It also allows you to have granular control by specifying controls for different types of protocols such as ICMP, TCP, UDP, etc within the ACL statements. Extended IP ACLs range from 100 to 199. In Cisco IOS Software Release , extended ACLs began to use additional numbers (2000 to 2699). The syntax for IP Extended ACL is given below: access-list access-list-number {deny | permit} protocol source source-wildcard destination destination-wildcard [precedence precedence] Example : access-list 110 permit tcp any eq 80 ACL 110 permits traffic originating from any address on the network. The 'any' statement means that the traffic is allowed to have any destination address with the limitation of going to port 80. The value of / can be specified as 'any'.