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Showing posts from October, 2007

CCIE IP Precedence Vs DSCP Values

The Table bellow Represent the TOS filed in the IP HeaderIPP IPP IPP DropP DropP 0 ECN ECN Drop P = Drop Precedence IPP = IP Precedence The Drop Precedence means the probability that the packet will be dropped, the higher the value it is more likely to be dropped. IP Precedence is the importance value of a packet, the higher the value the packet is more valuable. In IP Precedence we have 0 – 7 values and you can see that by looking into the amount of fields that we have Routing (Best Effort) - 000 Priority - 001 Immediate - 010 Flash – 011 => mainly used for Voice Signaling or for Video Flash-Override - 100 Critical – 101 => mainly used for Voice RTP Internet - 110 Network - 111 You do not need to remember the name value of each one, you can simply see it with: TermServ(config)#access-list 100 permit ip any any precedence ?(0-7) Precedence valuecritical Match packets with critical precedence (5)flash Match packets with flash precedence (3)flash-override Match packets with …

CCIE INTERNETWROKEXPERT

I would like to express my grate appreciation to the contribution that Internetworkexpert brings to the Technical Community, although they are a commercial company they do give away free seminars and do help people that are in need to learn and do not have a lot of financial resources to do that.So Thank you InternetworkExpertHere is a recent v-sminar that was added on IPv6 http://classroom.internetworkexpert.com/p23982603/Soon they will release a v-seminar that was transferred yesterday for free on Catalyst QoS.Also grate thanks to there top notch instructors:Brian Dennis, CCIE #2210 (R&S/ISP Dial/Security/Service Provider)Brian McGahan, CCIE #8593 (R&S/Service Provider/Security)THANK YOU!

CCIE SecureCRT Tip

As you all know the mostly used terminal in the CCIE lab exam is the old SecureCRT from http://www.vandyke.com/ without the tabs addition. but what you do have is the key mapping.you can set for example:F6 to be the CTRL SHIFT 6+x by simply setting the send sting in the key map to \036xF7 to be CTRL SHIFT 66 sequence of braking in the middle of a trace or a ping when you connected with the Access Server by mapping \0366 I my self practicing without the shortcuts but each person with its own methods and tactics. I believe the quest is like a preparation for theOlympics so practice practice practice.

CCIE VERIFY RPF FAIL

One of the major issues with Multicast is finding the RPF and making sure that there is no Failure in it, as if we do have a fail we can patch it by adding ip mroute (like a static route but only to pass the RPF, not actually changing the path of the packet). So how we can find such fail we have several tools the first one is to find if we have rp mapping. R6#sh ip pim rp ma PIM Group-to-RP Mappings Group(s) 224.0.0.0/4 RP 150.1.5.5 (?), v2v1 Info source: 150.1.3.3 (?), elected via Auto-RP Uptime: 00:14:48, expires: 00:00:02 R6# we see here in that example that we do have RP Mapping so we defiantly passed the RPF. I have made an RPF fail and we now will try to trace it: R6#sh ip mroute count IP Multicast Statistics 3 routes using 1962 bytes of memory 3 groups, 0.00 average sources per group Forwarding Counts: Pkt Count/Pkts(neg(-) = Drops) per second/Avg Pkt Size/Kilobits per second Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc) Group: 227.0.0.1, Source co…

CCIE PIM AUTO RP

In that section I would like to talk about Auto-RP, well not until recently I have had little to say about multicasting as it was something I know but like most I didn’t really understand or have struggled to really see how it works, I only know that when you enable it, you basically save bandwidth by using one stream instead of unicasting to each and every station, and on the basic it is true but the how it works is more important for us candidates. So here I will show you how the Auto-RP works and what tools do we have to make it work. Well we should all know that we have today 3 basic operation modes of PIM Sparse Mode – or as it called source tree and it is mostly used today Multicast Networks using a Pull Technology meaning if you do not ask I will not send it Dense Mode – or as it called shared tree and this is the very basic of Multicast using Push Technology meaning I will always send and if you say you do not need it I will Prune back but after a certain time out I will ag…