Thursday, February 16, 2017


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
                                      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 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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