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This is one of multiple SPF videos.

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I was asked to explain Oh SPF multiple areas and this is one of multiple videos helping explain how

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SPF works when you have multiple areas configured so we've now configured rather one and rather two

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rather one is once again only running.

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Yeah.

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GOP as shown here.

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Brought it to is running multiple writing protocols so we are running both EAI GOP

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and always P.F..

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So let me just do that a sure run it's running both yea GOP as well as always P.F. this command redistributes

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Oh SPF into each job he or translates if you like oh SPF into E.R. GOP in the same way that you would

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translate French into English and it sets what's called the seed metric or beginning metric to try and

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set an initial value for the root when it's redistributed.

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That's because we have to translate or convert over SPF which only supports bandwidth into EAI GOP which

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supports bandwidth and delay as part of its calculation okay.

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So let's configure wrote a three I a three in this topology is a area border rather it has an interface

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an area one and an interface in areas zero so hostname router 3 interface gigabit 00 no shut IP address

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10 1 2 2

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select 24 mosque interface gigabit 0 1 no shut IP address 10 1 3 1 slash 24 interface loop back zero

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IP address could ripple 3.

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Now here's another question for you.

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Can you run SPF without a backbone area.

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Someone enable a P.F..

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I'm only gonna enable SPF on gigabit 00 in Area 1.

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Will that work.

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Notice neighbor relationship has gone to full.

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So show IP SPF neighbor router 3 has a neighbor relationship with Robert 2 and we are receiving always

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preference what are called E2 grants or external runs from broader one and we can ping the loop back

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of wrought one on rather one debug IP.

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Icmp ping that loop back notice we see the echo replies sent from right one back to rather three.

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The traffic is definitely getting to write of one.

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So this is the thing to remember.

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You can and this is not an exam answer.

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This is a real world answer.

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You can.

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Not that you typically want to do it but technically you can run away SPF in an area that's not area

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zero.

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If this is the big if if you only have one area at the moment it works fine because we only have area

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one configured but as soon as we want to configure multiple areas we need to configure the backbone

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area or area zero.

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So what we'll do now is enable 0 SPF on the loop back in area 0 and on gigabit 0 1.

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We'll put both of those interfaces into area zero.

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So now show IPO SPF interface brief the loop back and gigabit 0 1 are in area 0 gigabit.

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0 0 is an area 1 so that's the configuration of router 3.

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What you'll notice as well is Rado 1 running EAI GOP is learning about the loop back of rudder 3 because

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router 3 is advertising the loop back to rudder to using a SPF and that's redistributed into EAI GOP

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and advertised to run a 1 Okay.

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So we've configured router 3.

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Now let's configure rudder 4 which has a backbone rather so bypass the initial configuration dialog.

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We don't want to configure the rudder that way host strata for interface gigabit 00 no shut IP address

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10 1 3 2

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so that's the IP address once again interface gigabit 0 1 IP address 10 1 4 1 no shut that credit loop

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back.

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This is gonna have a slash 32 mosque so do show IP interface breach.

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They are the IP addresses configured this road is fairly simple to configure.

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All we're going to do is configure OS SPF on all interfaces.

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Using this command some simply to enable 0 SPF everywhere.

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So show IP of SPF interface brief notice 0 SPF is running on all interfaces of the Rada.

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Notice a neighbour relationship was formed to write a three says show IPO SPF neighbor.

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We have a neighbour relationship to write a three show IP rort.

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We are learning multiple types of OSP France.

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We have got what are called intra area routes.

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Those are rorts that exist in the local area.

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In this case area zero we have what are called into area routes.

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Those are routes that exist in a different area and then we have external rots.

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Those are routes that originated from a different writing protocol so show IP SPF database will show

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us more details.

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We have two routers at the moment configured in area zero rudder three and rudder four have interfaces

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in area zero.

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We have one designated rudder that's rudder three for this link.

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We have type three routes.

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These are summary link state advertisements or summary LSD so type 1 LSA is a Rada LSA type to LSD are

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advertised by designated riders and advertise segments such as the segment 10 1 3 0.

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They are type 2 LSD.

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These are top 3 LSD or summery LSD.

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They advertise rots from different areas into 0 P.F..

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We also have a type for LSA.

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This is an LSA identifying the autonomous system border rather which is right too.

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We don't see this in area 1.

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It's a sharpie or SPF database because that road exists in Area 1 but for other areas to get to the

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ESB are a summary EPR advertisement is pumped in by the AP are so essentially right 3 is telling rather

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for how to get to the autonomous system border rather and then we have what are called Type 5 LSD.

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These are LSD that come from outside of our SPF so those rods come from EAI GOP and we can see them

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in the running table as this and this the local Rada should be able to ping the loop back of right of

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one which it can we can see the debug shown on Route 1 so that's right for configured let's configure

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out of 5.

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Hope you found his video useful if it's been of benefit to you.

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Please like it.

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And please subscribe to my YouTube channel.

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I wish you all the very best.