CCNP Certification / BSCI Exam Tutorial: EIGRP Stuck-In-Active Routes

Passing the BSCI exam and earning your CCNP is all about knowing the details, and when it comes to EIGRP SIA routes, there are plenty of details to know. A quick check in a search engine for “troubleshoot SIA” will bring up quite a few matches. Troubleshooting SIA routes is very challengin in that there’s no one reason they occur.

View the EIGRP topology table with the show ip eigrp topology command, and you’ll see a code next to every successor and feasible successor. A popular misconception is that we want these routes to have an “A” next to them – so they’re active. That’s what we want, right? Active routes sound good, right?

Well, they sound good, but they’re not. If a route shows as Active in the EIGRP topology table, that means that DUAL is currently calculating that route, and it’s currently unusable. When a route is Passive (“P), that means it’s not being recalculated and it’s a usable route.

Generally, a route shown as Active is going to be there for a very short period of time by the time you repeat the command, hopefully that Active route has gone Passive. Sometimes that doesn’t happen, though, and the route becomes SIA – Stuck In Active.

A route becomes SIA when a query goes unanswered for so long that the neighbor relationship is reset. From experience, I can tell you that troubleshooting SIA routes is more of an art form than a science, but there are four main reasons a route becomes SIA:

The link is unidirectional, so the query can’t possibly be answered.

The queried router’s resources are unavailable, generally due to high CPU utilization.

The queried router’s memory is corrupt or otherwise unable to allow the router to answer the query.

The link between the two routers is of low quality, allowing just enough packets through to keep the neighbor relationship intact, but not good enough to allow the replies through.

To sum it up, routes generally become SIA when a neighbor either doesn’t answer a query, or either the query or reply took a wrong turn somewhere. I told you it wasn’t the easiest thing to troubleshoot!

What NOT to Do on the AP US History Exam

The APUSH Exam is statistically the most difficult AP exam given by the College Board. Passing can mean some hardcore studying but knowing what not to study and what not to do on the AP exam can lower the amount of time you do spend studying. Here are 5 tips that every AP United States History student SHOULDN’T do on the AP Exam.

1. Rush Through the AP Exam
Take your time when you are taking the APUSH Exam. Rushing can be a real killer to your score, especially since the college board likes to set up traps for students that are rushing. Try to pace yourself. Don’t take too much time. Try to find a balance between the two.

2. Trying to Answer Every Question
One BIG thing I among other AP teachers preach is skipping questions that are giving you trouble. If you come across a difficult question skip and save it for later. When you have time, go back and try to answer it. You lose too much time and possible points when you try to answer these hard questions up front. That’s why its best to skip them and answer the easier questions first.

3. Not Eating Breakfast
There have been numerous studies that show that by eating breakfast you perform better when taking tests. Make sure you have enough time in the morning to eat a delicious breakfast. The extra boost of energy could make the difference between failing and passing.

4. Writing like a Maniac
Try your very best to write legibly. If you write like a crazy man it might be difficult for the AP graders to really understand what your trying to write about. When people come across a paper they can decipher then it knocks down their view of that paper. They have specific instructions to treat each paper as equals (racism is bad!), but sometimes you just cant help it. Bad impressions are hard to shake. Moral of the story is… trying to write legible = Happy AP graders.

5. Leaving Questions Blank
As of 2011 guessing on the AP U.S. History Exam does not effect your score what so ever. It used to be that if you got a question wrong you would lose points, but the college board saw their evil ways and decided to revert to the traditional grading system. This does however increase the questions you have to get right, but that’s alright, you’re a smart kid. So if you’re running out time on the AP exam don’t hesitate to guess on the questions you haven’t answered.