a vrf is a virtual routing table we saw it working with static routes in part
one and now it's time to see it with dynamic routing we're going to configure
our vrf aware OSPF EIGRP and bgp we're going to take the first
apology we've worked on that's the one without the firewall and expand on it
customer a wants to run OSPF customer B wants to run AI GRP we're going to make
that happen we'll start on the core router by finding and removing static
routes of a customer a that we created in the last video now will enable the
OSPF process when we enter into the OSPF configuration we specify the vrf that we
want to interact with we also configure the router ID and advertise the transit
network this is part of the normal OSPF configuration it's nothing specific to
vrf now we can bring up the customer our and we'll work on the OSPF there the
first step is to change the OSPF network type on the loopback interfaces the
network type needs to be set to point-to-point this is because of some
strange OSPF behavior this is not the era of specific if we don't set the
network type on loopback interfaces only the / 32 address on the loop box will be
advertised not the entire slash 24 so this is not something that you'll
normally want to do in the real world this is more of a lab type thing now we
can start the OSPF process and advertiser networks
as soon as we advertise that transit network the neighbor relationship forms
with the core router now back on the core router we can see the customer
router as a neighbor no special vrf commands are required for this we can
also see the routes in the OSPF database and if we look in the global routing
table we can still see that it is empty as expected the vrf has loaned the
customer routes and finally we confirm connectivity we pin now it's time to get
customer be configured with EIGRP the first step is finding and removing the
old static routes
and we're going to ERG our PE configuration if I can get this command
right you'll probably notice that we're using EIGRP in named mode this is
relatively new and the way of the future so that's why I'm using it here in EIGRP
we specify the vrf under the address family in named mode we also need to use
an autonomous system number once we're in that sub configuration we can
advertise the transit network and we need to configure the customer
router as well as you expect there's no need for vrf config here we do however
still need the address family this is a requirement of name mode
as soon as we advertise the transit network we see the relationship coming
up and while here we also advertise the rest of the networks
we can verify that this is working back on the core router
here we can verify that the customer router is a neighbor we do need to
specify the vrf when we're using eigrp commands the topology database also has
the routes that we need these routes are also in the customers vrf and finally a
ping confirms that we have connectivity
customer B has just informed us they would like to connect it to their way in
we don't own the customers when router ourselves so we would like to use ebgp
to pair with it our a s number is 65,000 and there's a 65 double O one as usual
the basic configures done which you can download from the website
we'll start by looking at the way and router there are no V refs over here so
normal bgp config is required that includes bringing up the bgp process
configuring a neighbor and advertising the networks
the really interesting config happens back on the core router bgp is very
complex so to support it we need to set up a unique identifier on each vrf that
BGP interacts with this identifier is called a route distinguisher I'll
explain more about how this works later but for now just be aware that it makes
vrf routes unique in the BGP database we'll also create a loopback interface
so BGP can have a router ID now to configure BGP itself VR F's are also
configured as part of an address family when we configure a neighbor here the
peering comes up
as you would expect we also have to advertise the customer and transit
networks into the win
at this point the customer rouse I will be able to reach the win why because it
hasn't learned the routes yet to fix this we go back into EIGRP and
redistribute BGP as we're using named mode we need to go into the topology
base some configuration mode if you've redistributed routes into EIGRP before
you may previously have set the metric to all ones this doesn't work anymore in
named mode so we need to be a bit smarter with a metric if we want tracer
up to work we also need to advertise the when transit link now to verify let's
start by looking at the BGP neighbors this uses the show IP v GP VPN v4
command when V RFS are involved as far as bgp is concerned these are no longer
simply ipv4 routes remember how we added a route
distinguisher into the vera changes held the prefix looks in the BGP
database so now it is known as a VPN v4 prefix you know what we'll go into
detail on that in the next video well we can see that the neighbor is up and
we've received prefixes let's have a look at their routes just bear with me a
moment I'm having trouble remembering the exact syntax when V ahrefs are
involved uh-huh okay I've got it we don't use the IP keyword with V ref
as I was just saying these are not IP routes anymore they're VP and v4 routes
and you can tell this because the realist English reset which we can see
here
the routes have successfully been installed in the routing table
and ping is also fine we should also check that the customer has access to
the win the wine routes have been learned notice that their GRP external
routes as they were redistributed from BGP ping also works so we have
connectivity let's try a trace route when iOS users trace route it uses DNS
to look up each hop which makes it exceedingly slow I'm going to speed this
up a little bit by disabling DNS with the no IP domain lookup command
and now we can definitely see if that traffic is going through the core router
to the win as we've been going through this I've mentioned a few times that VR
F's are local one router does not even know if another router is using varus a
lot but what happens if your core network has many routers we can make it
a bit simpler by using BGP this is where route distinguishes and route targets
come in and guess what we're going to make that happen in the next video