Cisco Nexus 7K – Secret decoder ring
Back when I first starting using the 7K’s I thought the naming of the line cards followed the same logical naming scheme of all other Cisco equipment (by that I mean there is no logic to it at all!). It was when I was watching one of this years Cisco Live presentations on the 7K architecture that it all became a lot clearer. So without further ado here is how to use the magical Nexus 7K linecard decoder ring: N7K-M224XP-23L N7K – Signifies that the card is for a Nexus…
Cisco RIB operations – AD comparisons
A post over at the IEOC forums got me thinking to something I picked up a long time ago but I can’t really remember where…
When a prefix arrives at a device from two different sources the AD is compared and the lower AD wins out, simple CCNA level stuff right? Well what if the AD is the same due to AD manipulation?
EDNS0 – DNS Extensions and their issues with ASA’s
EDNS0 – DNS Extensions History There are a growing number of issues that we have seen relating to this quite old however only recently used extension to DNS called EDNS0. The extension was originally outlined in RFC2671 which was published in 1999. The idea behind these extensions was that the DNS packet itself had a hard limit to its size when originally implemented and nowadays with more and more being done via DNS we had exhausted this hard limit. One solution would have been to simply extend the size of…
IPv6 MLD Snooping
I have finally finished my first read through of the CCIE R&S Written OCG and now is time to lab out some of my weaker points, read through a pile of RFC’s and then eventually book and take the exam. I thought today I would do a post on MLD snooping on Cisco switches. If you have ever configured IGMP snooping for IPv4 then this is pretty much identical! For this test I used the below topology which comprises of 4 routers (7206VXR’s in this case on Dynagen) and 1…
FRTS Fun…. (Frame Relay Traffic Shaping)
Over the past week or so I have been going over FRTS for my CCIE studies. It’s something that I have covered before when studying for my QoS exam and skimmed over when studying for my ROUTE exam but up until now it has never actually stuck. As others on Twitter have suggested maybe it’s because FRTS is an old technology and not really used anymore, that may be the case but I still remember all the intricacies of frame-relay and those have no problem staying in. In this post…
Another one bites the dust – BGP+MPLS (642-691) PASSED!
It has been some time since I last updated the blog but that isn’t to say that I haven’t been working/studying away. After finishing Internet Routing Architectures by Sam Halabi which alongside what I have learned both during my CCNP studies and whilst at my day-to-day job was going to serve as my reading to then go ahead and do the CCIP BGP exam. Before taking the BGP exam I started reading MPLS Fundamentals by Luc D Ghein and then decided that I felt that I would be comfortable enough…
MPLS QoS Marking : The rebuttal
Earlier today Ivan Pepelnjak over at IOS Hints (url / @ioshints) posted a piece on his blog in which he mentioned the behaviour of MPLS QoS markings and how they don’t copy over upon label imposition at the edge-LSR (the post is here). Having only looked at this very same topic a couple of weeks ago I was almost certain that this was not the case, and so I set out to lab it out and either prove myself or Ivan wrong…. My setup for this lab is as follows:
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