This topic is to discuss the following lesson:
Very Good Explanation!
If we are connected different clients with a L3 Switch , we can used this command (Passive Interface) to stop hello packet to clients.
My question is , if make Passive Interface Defaults on all interface (directly connected to other router) should Adjacency will be there or will be stop ?
The adjacency will be killed. If you use passive-interface on all interfaces then you need to use no passive-interface for the interfaces that require an EIGRP neighbor adjacency.
tnks rene bedant
Great and easy to understand lesson. I would only make one request on this for something to be added.
in my lab of this lesson everything went smoothly. Only thing I had some hiccups on that I had to search was the following.
I knew how to setup from the lesson the default command for passive interface. However, for some reason I was thinking “incorrectly” that I needed to setup the no passive-interface command under the interfaces… I tried a few times but it was not working for obvious reasons as that was the wrong place. Its small thing and I quickly did a search and found out what I was doing wrong. However, that would be nice to specify that went under the Eigrp router command.
(Just a note you do explain this fully under OSPF passive interface lesson so I should have known better but I tend to forget as much as I learn at times lol)
I know being able to think for ourselves and not having our hand held and figure out some small things on our own is good life experience but just figured I would mention it. Also I love posting on these forums in particular as this website is the best website to learn routing and switching I have came across in my lifetime.
In EIGRP just like in OSPF, it is possible to set the default state of an interface as passive with the
passive-interface default command under the
router eigrp configuration. This is explicitly explained in the OSPF passive interface lesson found below, but not in the EIGRP passive interface lesson.
I will inform Rene about your suggestion to add it explicitly in this lesson as well.
I’m very pleased that you find this forum useful for you in your studies and your endeavors to obtaining your CCNP and beyond. We’re glad that we can be of help!!
In your introduction video to EIGRP and every other book that I read, it says that
EIGRP hello messages are sent using multicast address 220.127.116.11
but this debug says otherwise. Can you please clarify?
R1#debug eigrp packets hello
EIGRP Packets debugging is on
EIGRP: Sending HELLO on FastEthernet0/0 AS 12, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 EIGRP: Sending HELLO on FastEthernet0/1 AS 12, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0
Update: find out why
R1#debug ip packet IP packet debugging is on R1# *Feb 3 18:31:23.715: IP: s=192.168.13.1 (local), d=18.104.22.168 (FastEthernet0/1), len 60, sending broad/multicast *Feb 3 18:31:23.715: IP: s=192.168.13.1 (local), d=22.214.171.124 (FastEthernet0/1), len 60, sending full packet
Great to see that you’ve solved the issue. Thanks very much for sharing your findings with everyone, it’s always helpful and adds to the richness of the forum.
I still don’t get how can u advertise an interface without making it send hellos massages.
if perhaps as u said in the lesson I’ll put a passive interface on Fa0/1 how would R2 know how to get to 192.168.10.0 ?
Let’s say you have a router R1 with the following configuration:
FastEthernet 0/1 has an IP address of 192.168.10.1/24
FastEthernet 0/2 has an IP address of 10.10.10.1/24
FastEthernet 0/3 has an IP address of 172.16.2.1/24
Here’s the topology:
Now let’s say that we’ve included all three subnets in the EIGRP process using the
network command. This means that all updates R1 sends will contain all three subnets. Now by default, EIGRP will sent out hello and update packets out of all of its interfaces. But as you can see in the diagram, there’s no point i sending these updates out of Fe0/2 and Fe0/3 because there are no routers attached to these subnets. So, we can make these two interfaces passive.
Now this doesn’t exclude the networks on these interfaces from participating in EIGRP, but it just says that these physical interfaces will not send out EIGRP hello and update packets. From this you can easily see that R2 will still get an update that contains all three networks. So even networks on passive interfaces are advertised, just not via those interfaces themselves.
I hope this has been helpful!