Posts

CEF: show commands

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this demonstrates that IP CEF is not enabled, until SVIs are created: Once SVI is created, CEF tables are created too, and stay there even if we delete the vlan and the SVI: Now we set back vlan 101 and its SVI. We display the FIB table: We do a ping to the attached host (in the vlan). A new entry is added to FIB: We create SVI 103. FIB is updated. Then we ping from host1 to SVI 103: Now let’s show the adjacency table AT:

QoS: Beyond The Term "Quality of Service"

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In this post, we will learn the following things about qos: why it is important to have a QoS policy, the traffic profile requirements for data, voice and video, how to define and implement a QoS policy. What is QoS, really? QoS can be defined as a way to ensure a quality of service of a transport system and to control its performance, especially in congestion time. It encompasses the following techniques: Classification Marking Congestion Management Congestion Avoidance Policing and Shaping Link Efficiency QoS helps network engineers reduce or eliminate the famous traffic performance enemies: delay, jitter and packet loss. But in no case can QoS substitute a bandwidth upgrade. For example, with QoS, we can select which packets to be dropped and which to be queued, thus even if packets are to be dropped, they won’t affect the most important traffics we have. Traffic profiles You might have learned in the past that there are data applications and multimedia applications. Here, we will t...

Vlan ACLs

A good Cisco document here I found an answer to all my VACL-related questions. A good thing to note here, is the way the author configures the “remaining traffic”. Here he defines another router ACL that says “permit any any” and uses it as a matching criteria for the remaining traffic. It also adds another VACL statement for that.

Conversation With a CCIE

One of my collegues is an old CCIE, from the days of Cisco WAN certifications. He worked with Telefonica, a big Spanish Telco company. He managed to take a bunch of spare routers to build a lab on his office desk. He studied for the written exam during three months, then took a year to pass the lab exam on his second try (from January to December). He studied during his free time at work, and during weekends. He also participated in a bootcamp. He said that it was helpful, because some guys have taken a first shot, and they have a feedback already on the lab exam. Tomorrow, a fresh CCIE is visiting the company. I’ll be glad to ask him some questions.

Almost 28 Days Later

The CEO rejected my resignation. He had a very strong personality and self-confidence, I admit it. In my one-and-a-half year of working at SATEC, I only discussed with him twice. In a second attempt to quit my job early, he refused. One of my collegues was blaming me. Some may be making fun of me. He told me that I made big mistakes. I don’t believe it. They are just mistakes, and I learned from them. At least, I’m courageous enough to get rejected twice despite what some people here may think. At least, I’m trying and growing. So what now? my future employer told me that it’s OK to wait for me until the 1st of March. Good news. Besides, I won’t care for the future of this company anymore. Everyday I’ll come here, have some chat, learn some Cisco stuff and leave. That’ll be the schedule until the end of this month. They wanted it that way, they’ll get it. A good thing too is that all of the Support team are cool. I enjoy their presence a l...

Almost Finished BCMSN first review

I have read and practiced almost all subjects. Now I need to review the ones I forgot. Yeah I am conscious that I’ve forgotten many concepts and configuration commands. So I need a second and maybe a third and fourth review. At the same time, I’m fed up with my job. No real challenges. I’m impatient to see who’s going to take my place as part of the current contract.

Trunking Notes

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There can be switchport trunk encapsulation negotiate on one side, and switchport trunk encapsulation isl | dot1q on the other end: