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Showing posts from October, 2008


Well I know this is not Cisco but I have just passed 30 min ago my JNCIA-ER exam with score of 90, to be honest that was one of the shortest test's I have ever had, usually I stay no meter what to the last minute but because I was pretty sure on my answers I have left after ~20 min.The resources provided from the site are excellent and answer 100% to the test questions. almost to good to be true.I must say that the last 3 weeks I have been playing with the junos (under my vmware setup) it seem to be realy nice and powerful OS.So for you professionals and experts I think it should be very nice knowledge edition, I am still thinking if I want to proceed with the JNCIS-ER exam or stop here with juniper, I will update you later.All of you have a nice weekend :-)

Spanning Tree Basics

Spanning Tree is one of the topics that most people a really scared as it is almost fully automatic feature People don’t bother to dig into it; my idea here is to give you a simple way to understand the protocol basics And also get a glance on its complex. First thing when I learn a new protocol I would like to look how it is working on the low level, so here I have drown you the BPDU structure, you can see that all implementations have a common ground and thus there is full backward support: Filed Description: PID = Protocol ID Always 0x0000 VID = Version ID 1) STP 0x00 2) R-PVST 0x02 BT = BPDU Type 1) STP 0x00 2) R-PVST / MST 0x02 TCN / TCN Ack is used only with IEEE 802.1D or with interoperation with RSTP. Proposal and agreement handshake are bits used to prevent loops, proposal sent from a designated port And agreement is sent from the root port. Unlike IEEE 802.1D in which any transition between the blocking and the forwarding state causes a topology change, Only transitions…