Valter Popeskic
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Valter Popeskic
Source-based routing in IPv4 and IPv6 networks
How does the internet work - We know what is networking
In my current studies I did some work about security inside networking data paths. In my recent work I tried to get some experiments done that needed to use source based routing in order to be completed. Like most of scientific work that tries to get from paper to experiment and then to something useful, it failed […]
BGP communities
How does the internet work - We know what is networking
O men, when you start to write about BGP it is probably the time then you seriously start questioning yourself where did I go with myself. That is probably the moment in which you realize that there is a network geek sitting somewhere inside you. At least that is what happened to me when I […]
VXLAN – Virtual Extensible LAN
How does the internet work - We know what is networking
As the time goes by and the network with more and more virtualised servers and other devices are making that network more complicated, overlay technologies are rising to save the day for network administrators. Virtual Extensible LAN – VXLAN is a new encapsulation technology used to run an overlay network on current Layer 3 communication […]
Redundant Default Gateway solutions in IPv4 networks
How does the internet work - We know what is networking
This article is an introduction to different default gateway solutions. Those technologies are enabling devices on IPv4 local subnets to have more than one Default gateway configured or at least some configuration that make them work half the way of ideal redundant solution. Idea behind this article is to be an introduction to a set […]
ICMP – Internet Control Message Protocol
How does the internet work - We know what is networking
ICMP protocol is a bunch of error, queries and response messages that are helping us every day to troubleshoot and manage our networks. At least if you found yourself in a networking engineer role. Network protocol “ICMP” is known as a control protocol because it is used for the purpose of administration and management within an […]
IPv6 Anycast Address type
How does the internet work - We know what is networking
IPv6 Anycast Address As the name says it’s an address that can exist more than once anywhere in the network. It is maybe better to say that it can exist in multiple places all over the Internet. This kind of address is basically enabling us to have servers and services physically closer to us as […]
Troubleshooting EIGRP Neighbor Relationships
How does the internet work - We know what is networking
EIGRP internals and getting hands dirty in debugging routing adjacency and solving EIGRP neighboring issues. What is sequence TLV and Conditional Receive CR-mode and CR flag Couple of days ago I got a strange network behavior in my CCIE lab. Something was wrong between a router and L3 switch connection and there was EIGRP neighbor […]
Packet capture in Cisco IOS
How does the internet work - We know what is networking
This will be a brief article but a good one. It will save you some walking time to server room. I have the need to capture traffic on the switch or on the router several times every week. That action needed from me to be physically near the switch and to configure SPAN port so that I can […]
CCIE RS v5 blueprint will be announced this month?
How does the internet work - We know what is networking
Please note that this article is more or less pure speculation. The fact is that CCIE R&S v5 blueprint will be presented 28th January 2014 on Milan’s Cisco live event everything else is yet to be announced. From Milan’s Cisco live 28.1.2014 there is an CCIE R&S v5 blueprint event scheduled. When Cisco wants to […]
GNS3 topology for INE Workbook
How does the internet work - We know what is networking
Now that my topology in GNS3 is exactly as in INE Workbook 1 I can share it with you if you don’t want to do all the basic configurations and connections by yourself. After spending too much money on different rack rentals in the past few months I decided that I will definitely need to […]
Forwarding UDP broadcast traffic mechanisms
How does the internet work - We know what is networking
We will speak here about some basics about Forwarding UDP broadcast traffic. If you were wondering what Forwarding UDP broadcast traffic actually is I will try to explain it here in few words. If you have more that one broadcast domains in your local network, let’s say that you have three VLANs. In normal networking theory it’s normal […]
IPv6 First-Hop Security
How does the internet work - We know what is networking
All methods to mitigate IPv6 security issues Real life security intro I the process of configuring our corporate network test segment for IPv6 support there was direct demand to pay particular attention to security. In few weeks it was my mayor role to go trough all materials I could get in order to learn more […]
MPTCP – Multipath TCP
How does the internet work - We know what is networking
Intro Multipath TCP is an extension of TCP that will soon be standardized by IETF. It is a succesful attempt to resolve major TCP shortcomings emerged from the change in the way we use our devices to communicate. There’s particularly the change in the way our new devices like iPhones and laptops are talking across network. All the devices […]
Administrative Distance for Static Route is 1 or 0?
How does the internet work - We know what is networking
There are different documents and books which are claiming that Administrative distance for static routes configured using exit interface is 1 and for the static route configured using next-hop IP address Administrative distance is 0. R1(config)#ip route 20.0.0.0 255.255.255.0 10.10.2.1 R1(config)#ip route 20.0.0.0 255.255.255.0 fastEthernet 0/0 This is not true. Both of them are having AD […]
Difference between defining static routes with next-hop address or exit interface
How does the internet work - We know what is networking
There were a bit of confusion in my head about this case. It was not clear to me what is the difference between setting the static route using next hop interface IP address or using exit interface syntax. It seems that both methods are the same and that you have basically two different ways to […]
Difference between defining static routes with next-hop address or exit interface
IPv6 Implementation beyond theory & How playing with RA messages may be issue-istic
How does the internet work - We know what is networking
Some of this things I read in books and some of them took me few days of troubleshooting and sweating to get to them so I give them for free here to save you fellow networker some time: SLAAC The mighty SLAAC is the prefered method of IPv6 allocation, but is it so mighty? Or it […]
IPv6 Implementation beyond theory & How playing with RA messages may be issue-istic
Cisco VIRL – Virtual Internet Routing Lab
How does the internet work - We know what is networking
Virtualisation In a world in which every day I hear virtualization at least 50 times it would be very strange that there is some part of our digital environment which is not yet virtualised. Today we can see that almost every piece of our server equipment is going to the cloud hence is being virtualised. That is not a […]
IPv6 RA Router Advertisement and all the flags inside
How does the internet work - We know what is networking
I can say at the beginning that more and more fellows is visiting this blog. Finally networking knowledge project did succeed to get some fans from out there so I felt the need to thank you all for visiting this place. As you can see here from the blog post list I didn’t follow this movement myself these […]
CCIE R&S v5 blueprint announcement?
How does the internet work - We know what is networking
UPDATE on 2.11.2013 – There will be an update in February 2014! Read all about the new announcement in the latest article here! with all new topics added and removed from CCIE lab exam v5. UPDATE on 23.07.2013 – There will be not update this year to v5 at least not for now… […]
DCCP – Datagram Congestion Control Protocol
How does the internet work - We know what is networking
DCCP transport layer protocol is used to control the datagram congestion. It provides an excellent procedure to stop the internet fall down, if it is caused by the congestion. In fact, this protocol is a brilliant competitor to be used as a substitute of UDP protocol. DCCP account DCCP congestion control trait by means of a reliable acknowledgments delivery (in form […]