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When you earned your CCNA, you thought you learned every little thing there is to know about RIP. Close, but not rather! There are some added specifics you want to know to pass the BSCI exam and get a single step closer to the CCNP exam, and one particular of these requires RIP update packet authentication.  [http://www.dailystrength.org/people/3014528/journal/6445966 disk security software]  You happen to be familiar with some advantages of making use of RIPv2 more than RIPv1, assistance for VLSM chief amongst them. But 1 advantage that you are not introduced to in your CCNA scientific studies is the ability to configure routing update packet authentication.  [http://www2s.biglobe.ne.jp/%257Esahmaro/Board/Board.cgi �f����]  You have two possibilities, clear text and MD5. Clear text is just that - a clear text password that is visible by anybody who can pick a packet off the wire. If you happen to be going to go to the trouble of configuring update authentication, you really should use MD5. The MD stands for &quot;Message Digest&quot;, and this is the algorithm that generates the hash value for the password that will be contained in the update packets. Not only should the routers agree on the password, they have to agree on the authentication method. If one router sends an MD5-hashed password to another router that is configured for clear-text authentication, the update will not be accepted. debug ip rip is a wonderful command for troubleshooting authenticated updates. R1, R2, and R3 are operating RIP over a frame relay cloud. Here is how RIP authentication would be configured on these 3 routers. R1#conf t R1(config)#important chain RIP &lt; The key chain can have any name.&gt; R1(config-keychain)#key 1 &lt; Key chains can have multiple keys. Number them carefully when using multiples.&gt;  [http://www.ucm.es/BUCM/wiki/index.php?title=Rose Rose - Wikipedia]  R1(config-keychain-crucial)#crucial-string CISCO &lt; This is the text string the key will use for authentication.&gt; R1(config)#int s0 R1(config-if)#ip rip authentication mode text &lt; The interface will use clear-text mode.&gt; R1(config-if)#ip rip authentication crucial-chain RIP &lt; The interface is using key chain RIP, configured earlier.&gt; R2#conf t R2(config)#crucial chain RIP R2(config-keychain)#important 1 R2(config-keychain-important)#crucial-string CISCO R2(config)#int s0.123 R2(config-subif)#ip rip authentication mode text R2(config-subif)#ip rip authentication important-chain RIP R3#conf t R3(config)#important chain RIP R3(config-keychain)#crucial 1 R3(config-keychain-crucial)#important-string CISCO  [http://www.stanford.edu/group/replusaction/cgi-bin/wordpress/activity/p/119067/ Re+Action: Scholar Activists, Social Activists &amp; Social Change Advocacy Resources]  R3(config)#int s0.31 R3(config-subif)#ip rip authentication mode text R3(config-subif)#ip rip authentication crucial-chain RIP To use MD5 authentication rather than clear-text, basically replace the word &quot;text&quot; in the ip rip authentication mode command with md5. Here's what a effectively authentication RIPv2 packet looks like, courtesy of debug ip rip. Clear-text authentication is in impact and the password is &quot;cisco&quot;. 3d04h: RIP: received packet with text authentication cisco 3d04h: RIP: received v2 update from 150.1.1.three on Ethernet0 3d04h: one hundred.../eight via ... in 1 hops 3d04h: 150.1.two./24 by means of ... in 1 hops Here's what it looks like when the remote device is set for MD5 authentication and the regional router is set for clear-text. You will also see this message if the password itself is incorrect. 3d04h: RIP: ignored v2 packet from 150.1.1.3 (invalid authentication) &quot;Debug ip rip&quot; may be a straightforward command as compared to the debugs for other protocols. but it's also a extremely effective debug. Commence utilizing debugs as early as possible in your Cisco scientific studies to find out how router commands actually operate!