Narrow Metric: We all know that by default the metric value for the ISIS route is 10 and it keeps on adding 10 on crossing every single link. For example, if the prefix has reached the router by crossing three links them the metric value associated with the prefix should be 40. See below example… Read More ISIS Metric types. Experimenting with wide and narrow metrics.
Hello Folks, Welcome to my blog, in this blog, I am going to discuss the method which I always apply to check if the ISIS protocol is working perfectly on the router or not. The same process will also give some tips to troubleshoot the protocol. So let’s get started. In case you want to… Read More GNS3 LAB: Cisco ISIS, How to verify and troubleshoot.
Convergence time is a problem that humankind is trying to resolve since the day IGPs were discovered. Every vendor keeps on pushing less convergence time. With low “hold time” intervals we somehow manage to decrease the convergence time but this also has a limit, and the chances of raising bigger problems increase when we keep… Read More GNS3 LAB : LFA(Loop free alternate) and RLFA(Remote-LFA) on Cisco Routers.
I have this topology along with 6 tasks published in my previous blogs regarding ISIS. Check here , ISIS Blog 1, ISIS Blog 2, ISIS Blog 3 . Now when I have covered the basics of ISIS I feel the need to explain the lab topology and tasks…below is the same ..have fun!! Task… Read More Cisco ISIS GNS3 lab tasks and few other details ….
ISIS Hello has information like as shown below in screen capture. Below are few of them which are frequently used. Circuit type L1 or L2 or L1 and L2 ? In this case it is L1 and L2 System ID: This 48 bit value is taken from the NET string we entered (49.0001.0000.0001.00) System ID… Read More ISIS Continued(Wireshark walkthrough)…..
Some more details about ISIS: Packet types in ISIS : Hello Packets : Just like other IGPs ISIS also uses hello packets to form the adjacency and as a keepalive mechanism. ISIS has many hello packets intermediate system to intermediate system hello(IIHs), End system to intermediate system hellos(EIHs- sent to mac 09-00-2B-00-00-05), Intermediate system to… Read More ISIS Continued…
WHY ISIS : As we all know that ISIS is making a comeback in form of entirely different forwarding technologies like Fabric path(Cisco), SPB(Avaya,Alcatel etc),Qfabric(juniper). Specially in the world of data center in coming few days you would see the necessity to learn ISIS. Considering this even Cisco has introduced ISIS in its CCIE RnS… Read More IS-IS basic implementation