CCNP Recertification

Posted on Friday, 1st April 2005 by sean

I’ve done a bit of work on NAT lately: NAT Overview NAT ip nat outside source I’m just going to finish up with the use of a route-map in NAT instead of the traditional access-list. As an administrative note, while adding new contact information on the lower right (Skype and AIM), I noticed that my [...]

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Posted on Thursday, 31st March 2005 by sean

Continuing on with the last article on NAT, I’m going to look at the ip nat outside source command. The network in question is: Bob is on the outside, and r1 is on the inside. I’d like R1 to connect to bob using the address of 5.5.5.5. That means an inside host will be using [...]

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Posted on Wednesday, 23rd March 2005 by sean

Getting back into things, I thought I’d do some practical work with NAT. I’ll go over the basic source NAT with overload, and then allowing an inside server to be accessed on the outside. First, pinging the server from R1 times out. Looking at it from the server (Bob): [root@bob ~]# tcpdump icmp tcpdump: verbose [...]

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Posted on Monday, 25th October 2004 by sean

While Network Address Translation, or NAT, doesn’t appear on the exam outline, I have heard from several sources that it appears on the composite exam. It’s also one of those topics that I’d expect to be tested on in the simulator. NAT is conceptually pretty easy — you’re manipulating addresses and possibly ports in order [...]

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Posted on Thursday, 23rd September 2004 by sean

I was going to start into BGP, but realized that I’d have to take a diversion into policy-maps at some point. Since policy routing is on the exam, I think this is a much better place to start. Identify the steps to configure policy-based routing using route maps It’s likely that your first exposure to [...]

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Posted on Monday, 23rd August 2004 by sean

In the last article about EIGRP, I’ll go over some of the show and debug commands relevant to the operation of EIGRP. Show the established neighbours: r0#show ip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq Type (sec) (ms) Cnt Num 1 192.168.1.136 Et0 13 00:00:29 404 [...]

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Posted on Thursday, 19th August 2004 by sean

There are many things that can be done to alter the behaviour of EIGRP. As we saw before, delay can be changed to make one link look worse than the other. Likewise, bandwidth can be changed, but since EIGRP uses the lowest bandwidth and the sum of delays, it makes more sense to play with [...]

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Posted on Sunday, 15th August 2004 by sean

When talking about DUAL, the stuck in active problem often comes up. One of the final things I showed in the last article was the behaviour of a router trying to find a lost route when there was no successor. The router “went active” on the route to find a new successor. Cisco has a [...]

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Posted on Saturday, 14th August 2004 by sean

EIGRP is easy to configure, but has a lot of options and can end up being very complex. Keep in mind that even though it looks and feels like a link state protocol, it is a distance vector protocol. Here’s the network for the next few examples (pardon the hand drawing): In addition, R2 and [...]

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Posted on Wednesday, 5th May 2004 by sean

Continuing on with the EIGRP articles, I’ll look at the EIGRP metric calculation. EIGRP uses a composite metric, meaning it’s made up of several smaller metrics: Bandwidth (minimum along path) Delay (cumulative along path) Reliability Load MTU A good way to remember them is Big Dogs Really Like Me. These correspond to numbers that come [...]

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