Nikolay Abromov blog

source http://evilrouters.net/2011/01/18/cisco-iou-faq/ What is IOU? From the Cisco Engineering Education web site (a long time ago): IOS on Unix (IOU) is a fully working version of IOS that runs as a user mode UNIX (Solaris) process. IOU is built as a native Solaris image and run just like any other program. IOU supports all platform independent protocols and features. What operating systems does IOU run on? It is my understanding that, initially, IOU was Solaris (SPARC) only. Nowadays, however, there are also builds for OS X and Linux. Similar to dynamips, IOU allows you to build out a network topology on a computer, without the need for physical routers. This is useful for validating designs, proof-of-concept testing, and certification self-study. Is my system compatible with IOU? You will need to be running the operating system that your IOU image were built for, obviously. Other than that, there are no special requirements to run IOU. It is not very CPU- or memory-intensive, unlik...

Just got another book for my collection. I am not big fen of MPLS/VPLS,however, this topic is mandatory in routing and switching lab. MPLS Configuration on Cisco IOS Software: A complete configuration manual for MPLS, MPLS VPNs, MPLS TE, Any Transport over MPLS (AToM), and VPLS (Networking Technology) [Paperback] Paperback: 720 pages Publisher: Cisco Press; 1 edition (10 Jun 2010) Language English ISBN-10: 1587142503 ISBN-13: 978-1587142505

I've been trying to find a good explanations on some of the Internetwork Expert tasks and why they decided to use the solutions they used in some of the tasks. I tagged all posts related to the labs with tag "ccienotes". The one bellow is related to IE lab 11; task 1.3. 1) General overview of STP convergence process 2) How STP converges if a directly connected link fails 3) How STP converges when it detects indirect link failure 4) Topology changes and their effect See more detailed overview at: http://blog.ine.com/wp-content/uploads/2010/04/understanding-stp-rstp-convergence.pdf STP Convergence in General As we know, STP protocol follows certain simple procedure to calculate the loop-free subset of the network topology. STP protocol could be compared to RIP in some sense. Both execute a version of Bellman-Ford iterative algorithm, which could be described as “gradient” (meaning it iteratively looks for the optimal solution, selecting the “closest” candidate every time). ...

--- cut --- By default, EIGRP will choose the path with the lowest metric. For this topology, the Point to point link between R1-R3 is 1.536 Mbps, frame-relay link between R2-R3 is 1.28 Mbps and the frame-relay link between R1-R2 is 256Kbps. In this scenario, R1 will choose Path 1 to reach VLAN 26. At this point if we configure the variance of 5, then the traffic will be load balanced between the two paths at a ratio of 80:23 as shown in the output below. RSRack1R1#sh ip route 164.1.26.6 Routing entry for 164.1.26.0/24 Known via “eigrp 100″, distance 90, metric 3026432, type internal Redistributing via eigrp 100 Last update from 164.1.12.2 on Serial0/0, 00:00:56 ago Routing Descriptor Blocks: * 164.1.13.3, from 164.1.13.3, 00:00:56 ago, via Serial0/1 Route metric is 3026432, traffic share count is 80 Total delay is 40100 microseconds, minimum bandwidth is 1280 Kbit Reliability 255/255, minimum MTU 1500 bytes Loading 1/255, Hops 2 164.1.12.2, ...