The other day whilst reading up on some SP topics I came across a rarely used function available on some higher end Cisco models called half duplex VRF’s (or HD VRF’s in some places).
I know it is quite a common thing to see in service provider topologies where you have a radius / virtual-template driven platform such as a DSL LNS etc but up until now I wasn’t aware that it can also be used on other platforms on regular (non virtual) interfaces.
For the demo topology I am going to use a faily simple network of three 7200′s in GNS3. According to the Cisco documentation here this feature has been around since 12.4(20)T or 12.2(33)SRC for the SR train.
In the topolgy I am using R1 and R2 to emulate customer sites which will be a member of the same VRF on R3 which will play the role of our PE.
Well today I got the confirmation through from Cisco that my lab attempt has been paid for and therefore there is no turning back now! Once you are within 90-days of your lab exam there are no changes or cancellations allowed which can seem a little extreme but I think it is more because of the fact that there are very limited amount of seats available. For those interested I will be taking the lab exam in Brussels on the 8th November, I had considered keeping the attempt quiet but…
Today I have been going through some more of the INE Vol2 labs and thought I would do a quick post on reflexive ACL’s. Reflexive ACL’s Reflexive ACL’s can be used as a basic kind of ‘stateful’ table on devices to allow traffic back inbound on already established connections. The reflective part of this feature can only be used on normal traffic flows where the inbound traffic is the same as the traffic that flowed outbound, this means it cannot be used for things like traceroute, VoIP (SIP) calls, FTP…
Over the past couple of days I have reviewed the remainder of the INE Advanced Technology videos that I felt that I needed to brush up on. I felt that before going onto the next stage that I needed to brush up on mostly some of the legacy QoS (FRTS included) and also the Catalyst QoS, I already felt pretty happy with it but as I don’t use it a whole lot day to day I felt it best to get it out of the way. Starting tomorrow I am…
Before christmas I started my way through the INE Vol1 advanced tech labs and got through the first couple of books, I think I was at RIP. Unfortunately because of a temporary resource issue with the CCIE rack I have use of combined with christmas, work being hectic due to a new DC rollout and my January holiday over to the USA the studies got put to one side. Since then I’ve moved out from my parents house (yes, get all the living with your parents jokes out of the…
Well all that studying seems to have payed off a little, today I sat the CCIE R&S Written exam (350-001) and passed it! Without going into any NDA-breaking territory the exam was actually pretty easy, partially caused I think by studying some topics at a much deeper level than I perhaps needed. During my time studying for the written exam I mainly used the Cisco Press CCIE R&S OCG but also used the INE Adv Technologies videos for some of the topics that I felt I needed more details on….
My next topic for writing up my notes is the security section. For this post and all posts following I will be using the CCIE blueprint from Cisco here (you may need CCO access to access that document but that is free). My reasoning for structuring it like this is to make it easier both myself to reference and hopefully someone else will find it easier as well. Some of the information is a little basic and will have been covered at CCNA and CCNP levels but seen as CCIE…
With under a week to go until my CCIE written test it’s time to go over my notes and get some of them written up to get them fresh in my mind. Todays notes of choice are my multicast notes. The notes may be a little sparse in places so if you can add anything or spot any mistakes please let me know. Multicast notes Common Multicast addresses Multicast AddressDescription 224.0.0.1All host group which contains all devices on the same network 224.0.0.2All routers group which contains all routers on the…
Earlier today there was an issue raised on one of our new(ish) ME3400 switches that we have started to deploy to customer sites. We started getting SNMP traps from it complaining that its CPU was maxing out, not something that we would expect to see from a switch, let alone a switch that was WELL within its operating limits. After jumping on sure enough the switch was showing a pretty high utilization on the CPU with regular spikes up to the mid 90% range. After some regular diagnostics by the…
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…
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