TroubleShooting OSPFv3 Address Familes Configuration

                          With the OSPFv3 Address Families Configuration we can have one hierarchical Configuration that contains our OSPF Configurations for both IPv4 and IPv6 Routing and there gonna be a single database maintain, we can give a single command and we can get information about both IPv4 and IPv6 and along with address Families, we got a new set of commands we can use for Verification and Troubleshooting and the great news is we can still use older commands we can still say for example

v  R1#show ipv6 ospf neighbor

                      Just using addressing family doesn’t mean that older command don’t work but now we have got new set of commands we could say

v  R2#show ospfv3 neighbor

               And notice this gives us information about our different Address Families one for IPv4, one for IPv6 before we look into more on these commands though i want to show you and remind you what the Address Family Configuration looks like, let’s do a

v  R2#show run | s router ospfv3

                We have got this one hierarchical Configuration structure

Router OSPFv3 and process ID of 1

And notice we have got two Address Families, one for IPv4 unicast, One for IPv6 unicast and it’s under these Address Families where we can configure the various OSPF parameter that we might want to tweak for example, i said that Area 1 is gonna be a STUB area but that’s only for IPv6 now let’s take a look at some more commands, we can use to get information from this combined database, similar to the

v  R2#show ipv6 ospf

Now we got a

v  R2#show ospfv3

That’s gonna give us similar information and there is not a replacement for the

v  R2#show ip protocols

v  R2#show ipv6 protocols

That’s not a replacement for that we can still use those if we want now let’s take a look at our interfaces that can say

v  R2#show ospv3 interface brief

                  And we can see for the different Address Families IPv4 and IPv6, we can see what interface is participating in specific ospf Areas but notice we all using the same Process ID of 1 its all into a single hierarchical configuration if we want to get more information about a specific interface, we can do that

v  R2#show ospfv3 interface f0/0

Ø  And we get thing like Timer Information

Ø  Router ID information

Ø  OSPF network type information, to look at our neighbors we can say

If we wanna look at Link State database, we can say

v  R2#show ospfv3 database

               And we first get to see the Link State database for the IPv4 Address Family and after scrolling down

                 We can see the IPv6 Address Families with all of its LSA’s and that the quick look of handful show command, we can use when Verifying and Troubleshooting OSPFv3 using to Address Families Configuration

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TroubleShooting OSPFv2 Routing Issues

                    In this topic, we wanna talk about some common reasons that Routes might not be appearing as expected in our IP Routing Table when we running OSPF on that Router. One Reason is that the Area to which an interface belongs where we trying to advertise the network for that interface maybe that interface is in an Area that is not adjacent to Backbone Area

                Remember, with OSPF we supposed to have a Backbone Area to which all other Areas connect we call it Area 0 or sometimes people configured as Area 0.0.0.0 but we just call it Area 0, any other Area needs to be adjacent that Area for example, we had an interface participating in Area 2 and in order to get from Area 2 to Area 0, we had to go through Area 1 Area 1 was a transit Area that’s not a valid Configuration because Area 2 is discontigues from the Backbone, that it’s not a best practice is not something you want to design in from the beginning but it’s a work around, i want you to know about we can have something called a Virtual Link

                       “A Virtual link allow us to logically span a Transit Area” we can go into the ABR’s, the Area Border Routers on each side of this Transit Area and we can configure them for a Virtual Link, so in example i was giving Area 2 can appear to be adjacent to Area 0 it’s gonna go over this Virtual Link which makes its look like a Direct Connection into Area 0 Virtual Link is a work around but not a best practice.

                          Maybe we have a more believable Routing Source if OSPF Says, here’s how to get to this network and EIGRP say’s here is how to get to this same network, the Router by default is gonna believe EIGRP because it has a Lower Administrative Distance remember, the default Administrative Distance of EIGRP 90 with OSPF it’s 110 it’s not as believable and

Ø  We might have a Directly Connected network

Ø  We might have a Statically configured network

                          That can also be more believable then OSPF, now keep in mind that we can go in and alter the Administrative Distance of Routing Protocol if we want to, we can go into Router EIGRP Configuration Mode or Router OSFP Configuration Mode and we can give the Distance command and we could set the Administrative Distance to non-default value but that’s one reason that Route might not be showing up as expected it’s not is believable as another Route pointing to very same network.

Another reason we might have OSPF Routing issue is we Filtering Routes

                      And Filtering works a bit different with OSPF that it does with EIGRP, now it’s good time to discuss OSPF Route Filtering and then we jump into a Trouble Ticket.

                  Let’s think about, why we might want to do OSPF Route Filtering we might want to do it for security reasons for example

Ø  Maybe we don’t want a Router to have a reachability to a particular network

Ø  Maybe we trying to reduce the size of the IP Routing Table in a Router by eliminating any unnecessary Routes

Ø  Maybe we trying to prevent a Routing Loops

                                 And the question comes up, how do we Filter these Routes and there are 3 primary ways we can do this and to illustrate these approach’s, let’s imagine a topology where we got a Backbone Area, Area 0 we got Area 1 and one of the Routers in Area1 is also connected to EIGRP Autonomous System

                   And remember, couple of these Routers have special Names, the Router that has one interface in Area 0 and another interface in Area 1 it’s called an ABR

                        It’s an Area Border Router, we also have a Router that’s an ASBR, an Autonomous System Boundary Router.

                        “It has at least one interface in an OSPF Area and at least one interface in another Autonomous System in this case its EIGRP Autonomous System” and when we doing Route Filtering with OSPF, typically we do either at the ASBR as a Routes coming in that external Autonomous System or we do at the ABR between our Areas, lets imagine that we got a network in Area 1

And that network is being advertised into Area0

And let’s ask yourself, how is that network going to show up in Area 0?

                 its gonna show up as “Type 3 LSA” which generated by ABR, let’s say we got a network in EIGRP Autonomous System

And it’s being advertised into OSPF, it’s gonna be advertised via “Type 5 LSA”

                  That’s generated by the ASBR and because of the way this works and ABR might be very appropriate place to Filter a “Type 3 LSA”, we can do that with a Filter List and ASBR it could be an appropriate place to Filter “Type 5 LSA” and that’s gonna be done is part of Redistribution Configuration

                           Something we talk more about in next our module but there is another approach let’s say that we want a Filter a Route from just one of those Router inside of Area 0, is that even possible with OSPF, can we tell OSPF to have a different Link-State Database for just 1 Router in Area.

                           NO! we cannot, that’s not allowed infect that violates one of basic concepts of OSPF we were saying that every Router in an Area needs to share the same Link-State Database about that Area, they need to agree on what to topology looks like, what’s the network on that Area, we not going to able selectively Filter Routes out of an OSPF Database for just 1 Router in an Area, however but if we did this

                         What we, let OSPF go head and learn that network, that we running to Filter Out, OSPF knows about in its RIB (Routing information base) remember that just because OSPF knows the Routes that’s no guaranty that Routes is gonna be injected into the Router IP Routing Table, the Route learn by OSPF is just a candidate to be injected into the IP Routing Table, so what if did this before OSPF could inject that Route into the IP Routing Table we blocked it, specifically we can configure something called a Distribute List and that can be used to block that Route from being injected into the IP Routing Table

                    Well letting that Route stay in the OSPF Database, OSPF knows about the Routes but the IP Routing Table does not. Those are 3 Primary approaches to OSPF Route Filtering that we might need to keep in mind, is we doing a Troubleshooting if we trying to determined whether or not a Routes is Filtered now let’s go to interface and Troubleshoot on OSPF Routing issue.

                    If we got neighborship, that’s not a guaranty that my Routing is working as expected for example, i notice on that Router R3 i am unable to ping the fastetherent 0/0 interface on Router R1, let’s try

Ø  R3#ping 192.168.1.1

                       That’s not looking good, we do seem to have a path to R1, i can get to its other interface lets confirm that

Ø  R3#ping 192.168.2.1

                      We do indeed have a connectivity to Router R1 so what’s going on here, we have got OSPF configured on all if my Routers, i thought that i told OSPF to make all of my interfaces participate in the OSPF Routing Process, here is the way in Router R3 that we can peer into the OSPF RIB, the Routing Information Base to see exactly what it has learned, what network is it know about, let’s do

Ø  R3#show ip ospf rib

       We actually do know about that, we know about that, we don’t seem to able to get to it, let’s look at IP Routing Table

Ø  R3#show ip route

                           There is a different Route in the IP Routing Table that says, here is how you get to 192.168.1.0/24 network it’s directly connected to Null0, which goes nowhere Oh! that’s the statically configured Routes

Ø  Maybe we did that to prevent traffic

Ø  Maybe for Security Reasons

Ø  Maybe we wanna to prevent traffic from R3 to that network

                               But let’s say that we determined, that’s what we don’t want to do, we actually want to be able to get that network we need to delete that Static Route remember,  those reasons we discussed earlier, we might not be able to learn a Route because we were Filtering a Route we talked about some other reason, one of those reasons was there is more believable Routing Source in this case that more believable Routing Source is this Static Route, lets fix this, let’s look at Static Routes

Ø  R3#show run | include ip route

That’s the command we want to remove off

Ø  R3(config)#no ip route 192.168.1.0 255.255.255.0 null0

Now let’s see if we know the better Route via OSPF

Ø  R3#show ip route

                              That looks much better, its say’s that we now know how to get there via OSPF, do we have connectivity now

Ø  R3#ping 192.168.1.1

And we resolved our Connectivity issue, our Routing issue

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TroubleShooting Named EIGRP

                        In this session, we wanna take a look at some commands we can use when troubleshooting Named EIGRP that’s a newer approach to configuring EIGRP

                                       The same underlying issues are essentially the same for named EIGRP as they were for EIGRP, for IPv4 and EIGRP for IPv6, we have some additional verification commands that i want to share with you in this topic, first let’s review some of basics of Named EIGRP and let’s understand why we might want to use in a first place, think about it with IPv4 it could be fairly easy to setup in EIGRP configuration we could say

Ø  Router eigrp given an AS Number and then say

Ø  Network 0.0.0.0

                                      And suddenly all of our interfaces that are administratively up they all participating now in this EIGRP process that was easy however, things start to get more complicated when we adding something for IPv6

Ø  We give some command under Interface Configuration Mode

Ø  Maybe we need to go into EIGRP for IPv4 Configuration Mode

Ø  If want to tweak any parameter for EIGRP for IPv6, we gonna go into that Configuration Mode

                          We got all these Different Configuration Modes we bouncing back and forth between and that can give bit of complexity but the great news is Named EIGRP lets us consolidate all of this under one Configuration Mode.

                  With Named EIGRP we take the function that we would normally have to configure under Interface Configuration Mode, EIGRP for IPv4 Configuration Mode, EIGRP for IPv6 Configuration Mode and we consolidate them together in what’s called EIGRP Virtual Instance

                        This EIGRP Virtual Instance is made up of One Configuration Mode and under this one Hierarchical Configuration Mode we can do everything we need to do, instead of going into lots of different Configuration Modes under this Virtual Instance, we can define an EIGRP Address-Family

                         We might create an Address-Family for IPv4 and we can create another Address-Family for IPv6 and its under Address-family Configuration Mode, we gonna setup the more general EIGRP parameter like our Router ID, we can say whether or not Router is in EIGRP Stub Router

                          Something else we can do from Address-Family Configuration Mode is enter an “Address-Family-Interface Configuration Mode” and as just a couple of examples things we can do here, we could set up an interface being a passive interface, we could set up EIGRP Timers here as well

                         There is also an “Address-Family-Topology Configuration Mode” here we give commands that has a Direct impact on router EIGRP topology Table, it’s here we could setup things like the Variance option where we could load-balance across Paths that have unequal metric

                              For example, let’s say that we have got two different ways to get to destination network one way has a metric of 1 million another way has a metric of 1.5 million, well normally we just gonna go with the best Route, i am gonna go with the Lowest Feasible Distance however, if we set our Variance to let’s say suddenly we can use that other Route, here is a way that calculation done we take the variance which is an integer we said 2 in this example, we could say 2 times the Feasible Distance we said that was 1 million so, 2 times 1 million is 2 million, by doing that we have now set the range of acceptable values, we are saying that if the metric is anywhere in the range of 1 million to 2 million, we can load balance across it and we said that alternate path had a metric of 1.5 million, Great news we can use that by setting the Variance and something else we can configure under “Address-Family-Topology Configuration Mode” is Redistribution maybe we got a couple of Routing Protocols running on Router and we want those Routing Protocols to exchange to Route information

                           And now the we reviewed some of the Theory of Named EIGRP, let’s take a look at topology.

                       Here in this topology on Picture, i have got all my Routers configured with Named EIGRP and when it comes to troubleshooting the same basic set of issues that we talked about last session dealing with neighborship and Routing issue, those some underlying causes still apply here as well but i want to do a separate session on Named EIGRP to show you some new Show Commands that we can use with this brand-new type of Configuration

First let’s take a look at our Named EIGRP Configuration, let’s do a

Ø  R2#show run | section router eigrp

                     And here you see, we defining this EIGRP Virtual Instance and i have got couple of Address-family, One for IPv4, One for IPv6 and i have set thigs up like

                    Variance of 2 for IPv4 and i given a network statement of 0.0.0.0 to make all of my UP/UP interfaces participate in the IPv4 EIGRP Routing Process

There is not really much to configure for IPv6 you just give the One Command

address-family ipv6 unicast autonomous System 2

                       And suddenly your interfaces that are UP/UP have an IPv6 address there participating in the Process but i want to show you some new commands, first remember the Command that

Ø  R2#show ip protocols

That we could use with IPv4 and

Ø  R2#show ipv6 protocols

We could use with IPv6, there is a similar command we have here is

Ø  R2#show eigrp protocols

                And notice, the output from this command gives us information about IPv4 and the IPv6 Process and we got information like K Values those have to match between our neighbors, Variance of 2 set here for IPv4 something that missing those specifically for IPv6 when we did a

Ø  #show ipv6 protocols

                 We got a list of interfaces that were participating in EIGRP for IPv6, we don’t get that here and the output of

Ø  R2#show eigrp protocols

                     And that reason many people prefer to go with older command however, there is a way to see what interfaces participating in this IPv6 Routing Process, we could say

Ø  R2#show eigrp address-family ipv6 interfaces

Ø  R2#show eigrp address-family ipv4 interfaces

                We could see what interfaces are participating and i can get additional information by adding the “detail” keyword to end of this command

Ø  R2#show eigrp address-family ipv4 interfaces detail

                      This is gonna show us things like “Hold Time and the Hello Time” by the way the Timers do not necessarily have to match between EIGRP speaking neighbors, with OSPF that’s something that does have to match between our neighbor’s timers have to match and its good practice Timers to match with EIGRP, you can form a neighborship with different Timers with EIGRP, something to keep in mind we also see the Split-Horizon enabled

Do you remember what split-horizon does?

Split-horizon says, “if i learn a Route coming into an interface i am not going to advertise that very same Route out of that interface” “if somebody tells me their Resume why? would i tell their Resume back to them that doesn’t make sense” however, if we were in a Point-to-Multipoint network maybe like a Frame-relay network where we got a Hub and Spoke topology, it’s possible that we might need turns this off so Route advertisement coming in from one of our Spoke Routers gets advertised back out of same interface to go to another Spoke Router and just like we can look at the interface Table that eigrp maintains we can look at the neighbors Table and Topology Table

Ø  R2#show eigrp address-family ipv4 neighbors

And we can see what IPv4 neighbors we have, we can do the same thing with IPv6

Ø  R2#show eigrp address-family ipv6 neighbors

We can take a look first for IPv6

Ø  R2#show eigrp address-family ipv6 topology

Those are the network known to EIGRP and we can do the same thing for IPv4

               That’s the look at few new commands that we can use to get information from our Routers that’s configured for Named EIGRP but please keep in mind, the older commands that we saw on Prior topic there gonna work to if we prefer to do those.

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