EIGRP Intermediate

Hi Rene,
Advertise these networks in EIGRP, the routing table on R1,R2 and R4 should only show a single entry for these networks: 172.16.1.0/22

Shouldn't it be 172.16.0.0/22??

Thanks,
Satya

Hi Satya,

You are totally right...I just changed it in the lab, thanks for mentioning this!

Rene

is that means to create static route for 1.1.1.1 from R4.

What is the command for metric change?
Is that ip route 0.0.0.0 0.0.0.0 next hop/interface

How to change the bandwidth on R2 on Interface fa0/0?

Thank You!!

sorry that static route command is for 1st one not for the EIGRP metric

You can use the metrics to influence routing decisions, for EIGRP it's bandwidth and delay.

You need to change this under the EIGRP process, use "metric weights tos k1 k2 k3 k4 k5" for this.

U need the "bandwidth" command on the interface for this.

Create a default route on R1, if you look at the routing table on R2,R3 or R4 it should show the default route pointing to R1.

How do we do this?

@Rene

Is there any config file included on this lab?

One way to advertise a default route with EIGRP is as following:

1) Create a static route 0.0.0.0/0 towards the Null0 interface.
2) Advertise or Redistribute this into EIGRP.

I think we have to redistribute.

by going through R2, the other one through R3. only use EIGRP commands to achieve this."

should i use the variance command?
if so i used it and even set all routers to a value of 128 and i'm still not getting 2 entries.
any advice?

@Avi I Just changed the goal so you can use bandwidth as well if you like. In order to have 2 entries in the routing table you'll need to use the variance command. The other path however has to be a feasible successor...make sure you see both entries in the EIGRP topology table.

Rene

Hi Rene,

i can't make the other path feasible succesor.
i've tried changing BW on R3 int fa 0/0 and it just won't work but when the BW is equal i get 2 succesors.
how can i make the other way a feasible succesor?
thx

Hi Avi,

Let me try to explain the feasible successor rule:

1) The best path is called the "successor".

2) The backup path is called the "feasible successor"...but it has to pass a certain rule.

3) The "total distance" from your router to the destination is called the "feasible distance".

4) Your EIGRP neighbors will tell you how far it is for them to reach the destination, this is called the "Advertised Distance".

5) In order to become a "feasible successor" the "advertised distance" has to be lower than the "feasible distance" of the successor". Or in plain english...the eigrp neighbor you want to use as a backup has to be closer to the destination than your best route. Otherwise it's possible that this backup path goes through you...(keep in mind, EIGRP is a distance vector protocol).

Take a piece of paper and write down some routers and metrics, see if you can determine on paper which router will be the successor / feasible successors and then try it on your real setup. The metric numbers on real routers are very high so kinda annoying to work with.

Have fun

i already knew the rules of EIGRP and did things correctly so i searched the web and i found out that some more people had the same problem and they needed to do the clear ip eigrp neighbors command so i did it and it works fine!

another question i have is about stub.
i configured R3 as stub but R1 still sends query messages can you explain this?
thanks for your time

Hi Avi,

Great that it works... About the stub...that's weird, If you configure R3 as a stub you see it kills the neighbor adjacency between R1 and R3?

Post the config for R1 and R3 if you can (EIGRP relevant part) and the output of the debug. On the forum you can add attachments if you want to show the full config, might be easier than the comments here. I'll take a look at it.

Rene

Re: "Advertise these networks in EIGRP, the routing table on R1,R2 and R4 should only show a single entry for these networks: 172.16.0.0/22"

On R3, I advertised the 4 loopbacks with (using the wildcard mask to get the /22):
R3(config-router)#network 172.16.0.0 0.0.3.255

On R1,R2,R4, when I Rx#show IP route (output from R4 shown):
172.16.0.0/24 is subnetted, 4 subnets
D 172.16.0.0 [90/156160] via 192.168.34.3, 000:29, FastEthernet0/0
D 172.16.1.0 [90/156160] via 192.168.34.3, 000:29, FastEthernet0/0
D 172.16.2.0 [90/156160] via 192.168.34.3, 000:29, FastEthernet0/0
D 172.16.3.0 [90/156160] via 192.168.34.3, 000:29, FastEthernet0/0

Any thoughts why I am not seeing just the 172.16.0.0/22 single entry?

@MikeG, you need to create a manual summary advertisement to avoid seeing the individual subnets.

Route from R3 to 1.1.1.1 is obviously good, but why doesn't it pass it on to R4. Tried dropping bandwidth down on R4 f1/0 no effect except larger metrics for same route.

Ive actually tried shutting down f0/0 on R4 and although there neighborship there is no route for 1.1.1.1 . Can you help me out on this as I really can't see why its behaving like this ?

I see I don't have a video for this one yet, time to create one...

@MikeG using the network command only determines what you are going to advertise. It will only advertise whatever you have on the interface, it's not going to summarize anything for you...that's what you have the summary command for. Since you have a network command with a wildcard that matches those networks they are advertised. Are you following me?

@Oliver is the entry not even in the EIGRP topology table? Does it pass the feasible successor rule? (AD Feasible Successor < FD Successor route?)

Re: "Advertise these networks in EIGRP, the routing table on R1,R2 and R4 should only show a single entry for these networks: 172.16.0.0/22"
Thanks Whoolio & Rene for your comments. I believe I've got it.

On R3, I kept the same advertisement for the 4 loopbacks (just to remind me about wildcard masks):
R3(config-router)#network 172.16.0.0 0.0.3.255

As anticipated, I got same result with classful advertisement:
R3(config-router)#network 172.16.0.0

On R3-F0/0, I added the manual summary for the 4 172.16.0.1-172.16.3.1 loopbacks:
R3(config-if)#ip summary-address eigrp 65000 172.16.0.1 255.255.252.0

Note that the actual command that showed up in Running-Config was:
ip summary-address eigrp 65000 172.16.0.0 255.255.252.0 5
With summaries, I thought I had to specify my lowest addr, but looks like I didn't need the .1
Note, too, that the IOS added a 5 to the end of the command, the default EIGRP Summary admin dist.

Because I had not added the summary to R3-F1/0 yet, I had this interesting result on R1:
R1# show IP route
172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
D 172.16.0.0/24 [90/161280] via 192.168.12.2, 0008, FastEthernet0/0
D 172.16.0.0/22 [90/156160] via 192.168.13.3, 00:197, FastEthernet1/0
D 172.16.1.0/24 [90/161280] via 192.168.12.2, 0008, FastEthernet0/0
D 172.16.2.0/24 [90/161280] via 192.168.12.2, 0008, FastEthernet0/0
D 172.16.3.0/24 [90/161280] via 192.168.12.2, 0008, FastEthernet0/0
Note the left over routes coming the long way around thru R4 & R2-F0/0 (higher metric).

On R3-F1/0, I added the same manual summary for the 4 172.16.0.1-172.16.3.1 loopbacks:
R3(config-if)#ip summary-address eigrp 65000 172.16.0.1 255.255.252.0

And finally, the desired result on R1 & R4:
R1# show IP route
172.16.0.0/22 is subnetted, 1 subnets
D 172.16.0.0 [90/156160] via 192.168.13.3, 00:26:20, FastEthernet1/0
R4# show IP route
172.16.0.0/22 is subnetted, 1 subnets
D 172.16.0.0 [90/156160] via 192.168.34.3, 001:26, FastEthernet0/0

One last question on this topic, Shouldn't I see an admin dist of 5 on R1,R2,R4 because of the default EIGRP Summary admin dist of 5?

Hi Mike,

Let me give you an answer to your questions/comments. I think this is useful for everyone studying EIGRP.

The network command is a bit funky so let me explain it a bit. It does 2 things:

A) Activate EIGRP on the interface.
Advertise the network that is configured on the interface.

It doesn't summarize for us (that's what we have summarization commands for). If you type in a network command then it will activate/advertise EIGRP on all interfaces that fall within the range of the network command. I think you got this Mike so this is more for everyone else that's wondering

Look closely at the subnetmask you configured:

255.255.252.0

If you use this subnetmask it means we have the following subnets in the 172.16.0.0 range:

Subnet #1 172.16.0.0
Subnet #2 172.16.4.0
Subnet #3 172.16.8.0
Subnet #4 172.16.12.0

etc etc.

172.16.0.1 is an IP address that falls within the first subnet. By typing in the IP address and subnetmask your router knows which subnet you are talking about and instead of giving you an error it will put the correct one in the config.

administrative distance is always local. It's not a value that is advertised between routers.

Quote:

Because I had not added the summary to R3-F1/0 yet, I had this interesting result on R1:
R1# show IP route
172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
D 172.16.0.0/24 [90/161280] via 192.168.12.2, 0008, FastEthernet0/0
D 172.16.0.0/22 [90/156160] via 192.168.13.3, 00:197, FastEthernet1/0
D 172.16.1.0/24 [90/161280] via 192.168.12.2, 0008, FastEthernet0/0
D 172.16.2.0/24 [90/161280] via 192.168.12.2, 0008, FastEthernet0/0
D 172.16.3.0/24 [90/161280] via 192.168.12.2, 0008, FastEthernet0/0
Note the left over routes coming the long way around thru R4 & R2-F0/0 (higher metric).

This is a good example of most specific routing. You are receiving the summary on one interface and the more specific routes through the other interface.

Administrative distance is only local for each router.

@MikeG,

Regarding your query..

You need to summarise under the outgoing interface for the other routers to see 172.16.0.0/22

these should do the trick
int f0/0
ip summary-address eigrp (asn no.) 172.16.0.0 255.255.252.0

and again for
int f1/0
ip summary-address eigrp (asn no.) 172.16.0.0 255.255.252.0

hi

also i got a problem about the goal which should use "variance"
i changed bnadwidth of the R2 f0/0 to 100 after i cant see the way through the 1.1.1.1 over R2 even in the "show ip eigrp top all-links"

as i know i should see the all links in the topology even it s not feasible router for the destination

do u have any idea ?

I'll upload the solution to this lab this week so you can check it. If you are unsure about variance you can watch some of the other EIGRP videos I have...I explain variance in them as well.

1.Without modifying R2, make sure R4 has 2 entries for the 1.1.1.0 network, one by going through R2, the other one through R3. only use EIGRP or bandwidth commands to achieve this.

2.Make sure that when you type 'shutdown' on Loopback1 at R2, R1 will not send a QUERY to R3. (hint: to check this, do a 'debug eigrp packets query reply)

Also when doing authentication do you need to do the ip authentication mode eigrp # command on the interfaces?

Thanks.

Hello Howard,

By default EIGRP will only place one successor router (best path) in it's routing table. If there are two equal paths it will do load-balancing and you'll see two entries in the routing table. Besides checking for the successor EIGRP will look if there's a feasible successor (backup path). You won't find the feasible successor in the routing table until the successor fails.

EIGRP however can do "unequal load-balancing" which means it can load balance over the successor and one or more feasible successors. You'll have to use the variance command to enable unequal load-balancing. If you configure this correctly R4 will have two paths to reach 1.1.1.0 /24.

When EIGRP loses a successor route and has no feasible successors it will send a query to its neighbors for the lost prefix. Take a look at the EIGRP Stub feature to see how it influences the query process.

Here's an example for EIGRP MD5 Authentication:

http://gns3vault.com/EIGRP/eigrp-md5-authentication.html

You need a key-chain and two interface commands:

key chain YOURKEYCHAINNAME
key 1
key-string PASSWORD

Interface Serial0/0
ip authentication mode eigrp 12 md5
ip authentication key-chain eigrp 12 YOURKEYCHAINNAME

Router EIGRP 12
network x.x.x.x

I hope this helps you!

Rene

Thanks Rene, great site.

RE:Make sure that when you type 'shutdown' on Loopback1 at R2, R1 will not send a QUERY to R3. (hint: to check this, do a 'debug eigrp packets query reply)

I am not able to find a solution to this. Can you please assist? My guess was to configure R3 as a stub, but when I shut down the loopback of R1 I find that R3 still "Ensues" an EIGRP QUERY.

@Howard Thanks Howard!

@Tim565ty Configuring R3 as a stub *should* be the answer to this question. An EIGRP stub router shouldn't receive any queries when a neighbor loses a successor router.

If you do a debug on R3 what do you exactly see?

R3(config)#int lo0
R3(config-if)#shut


R2#sh ip eigrp neighbors de fa0/0
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
0 192.168.12.1 Fa0/0 10 000:30 57 1458 0 60
Version 12.4/1.2, Retrans: 0, Retries: 0, Prefixes: 2
Stub Peer Advertising ( CONNECTED SUMMARY ) Routes
Suppressing queries


=====
R1#sh run | b router
router eigrp 1
redistribute connected
network 0.0.0.0
metric weights 0 1 0 1 1 1
no auto-summary
eigrp stub connected summary

============================
!On R1

*Mar 1 00:351.159: EIGRP: Enqueueing QUERY on FastEthernet1/0 iidbQ un/rely 0/1 serno 53-53
*Mar 1 00:351.163: EIGRP: Enqueueing QUERY on FastEthernet1/0 nbr 192.168.13.3 iidbQ un/rely 0/0 peerQ un/rely 0/0 serno 53-53
*Mar 1 00:351.171: EIGRP: Sending QUERY on FastEthernet1/0
*Mar 1 00:351.171: AS 1, Flags 0x0, Seq 62/0 idbQ 0/0 iidbQ un/rely 0/0 serno 53-53
*Mar 1 00:351.179: EIGRP: Enqueueing QUERY on FastEthernet0/0 iidbQ un/rely 0/1 serno 53-53
*Mar 1 00:351.183: EIGRP: Enqueueing QUERY on FastEthernet0/0 nbr 192.168.12.2 iidbQ un/rely 0/0 peerQ un/rely 0/0 serno 53-53
*Mar 1 00:351.183: EIGRP: Sending QUERY on FastEthernet0/0

I'll take a look at this. Your stub is configured to advertise the connected and summary routes.

Once I'll record the video I'll debug it and see what is going on....to be continued!

Hello, i have a problem i can open the topologie because i hav'nt the IOS of the router 3640 (c3640-jk9s-mz.124-16.bin)

Hi Mouhi,

You don't have to use the exact same IOS version...any other 3640 image *should* do the job.

Rene

can anyone help me. I'm trying to config r3 as a stub router.

If i do
R1#show ip eigrp neighbor detail
IP-EIGRP neighbors for process 100
H Address Interface Hold Uptime SRTT RTO Q Seq Type
(sec) (ms) Cnt Num
0 192.168.13.3 Fa1/0 10 000:55 521 3126 0 96
Version 12.2/1.2, Retrans: 1, Retries: 0
Stub Peer Advertising ( CONNECTED SUMMARY ) Routes
1 192.168.12.2 Fa0/0 12 00:20:46 32 200 0 111
Version 12.2/1.2, Retrans: 4, Retries: 0

R1 sees that R3 is a stub but If I shut R2 loopback interface I still get queries...Its strange.

0182: EIGRP: Enqueueing QUERY on FastEthernet0/0 iidbQ un/rely 0/1 serno 146-146
0182: EIGRP: Sending QUERY on FastEthernet0/0
0182: AS 100, Flags 0x0, Seq 104/0 idbQ 0/0 iidbQ un/rely 0/0 serno 146-146
0182: EIGRP: Received REPLY on FastEthernet0/0 nbr 192.168.13.1
0182: AS 100, Flags 0x0, Seq 159/104 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0

R3#show run | inc eigrp
router eigrp 100
eigrp stub connected summary

Why is R3 still getting queries from the f0/0 interface?

hey Rene
do you have the solution for this lab??
would you mind uploading it

thank you and sorry for my english

Yes I will do it asap.