topic Re: Layer 3 Switch cant communicate with Router (PT LAB) in Switching

Layer 3 Switch cant communicate with Router (PT LAB)

BrogsB12 — Wed, 15 Sep 2021 00:09:26 GMT

Hello world, newbie here,

I am working on a lab studying for the CCNA which is related to OSPF. The lab has 3 sites, AZ, NV and FL which when usingRouter on a Stick everything works to perfection. However, the instructor on his video doesn't have any sub-interfaces on the routers which led me to believe that he is using SVI's on the L3 switch(s) that connects to the edge router (topography attached) i could have let this go at theRouter on a Stick config w/ OSPF but i'm curious and want to learn how to config withoutRouter on a Stick (if possible) and now its been DAYS messing with configs on AZ with no result of the L3 switch communicating/ forming an adjacency with the router.

On my lab when using only SVIs on the AZ site, VLANS can communicate with each other but they don't get passed the default gateway i set for them on the L3 switch SVI and OSPF adjacencies are formed between the two core L3 switches but not the router on AZ.... YET, adjacencies are formed with all site routers and i can ping devices from NV to FL without issues; again i kept Router on a Stick there since a L2 switch is the main device there per the lab. Can anyone advise me on why this could be and yes i have enabled Ip routing on the switch and have the correct default gateway for the computers to get to.. just that after trace route the computers get to their respective gateway and stop there...

I tried various other things such as a new SVI to connect to the router for communication but its not working... i will add as details emerge ..

Re: Layer 3 Switch cant communicate with Router (PT LAB)

Georg Pauwen — Wed, 15 Sep 2021 02:12:47 GMT

Hello,

post the zipped Packet Tracer project (.pkt) file...

Re: Layer 3 Switch cant communicate with Router (PT LAB)

paul driver — Wed, 15 Sep 2021 05:16:23 GMT

You have 4 subnets and two of them overlap *
10.0.0.0/21 Arizona -10.0.0.1 to 10.0.7.254 *
10.0.7.0/28 Metro -10.0.7.1 - 10.0.7.14 *

10.0.8.0/21 Nevada -10.0.8.1 to 10.0.15.254
10.0.16.0/21 Florida -10.0.16.1 to 10.0.23.254

Regards using L3 on the switches you would create a svi for each subnet taken from there respective assigned ip range and then have either a default static route pointing upstream towards there related site rtr or enable dynamic routing between rtr and switch (OSPF)

Arizona - AZW1
svi 10-17

Nevada - NVSW1
svi 10-17

Florida - FLSW1
svi 10-17

On the site rtrs they should share a public address subnet (METRO -other than 10.0.7.0/28 and no NAT) so they can OSPF peer with each other (p2mp network type) and advertise their related site subnets.

Arizona -AZ-RT-1 -metro 172.16.1.1/29 (10.0.0.0/21)
Nevada -NV-RT-1 -metro 172.16.1.2/29 (10.0.8.0/21)
Florida - FL-RT-1 -metro 172.16.1.3/29 (10.0.16.0/21)

Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Sat, 01 Oct 2022 09:29:34 GMT

hi guys i need help urgently i have three routers and a switch between ,the router in the other side were not able to learn the two other router using OSPF and the other routers has the same issues i would send the packetracer task which would one do me a favor and see what is in the hands because im studying for CCNA exam.

Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Sun, 02 Oct 2022 11:42:14 GMT

can someone help me urgently for the topics posted above im very thankful to you

Re: Layer 3 Switch cant communicate with Router (PT LAB)

NetworkDave — Sun, 02 Oct 2022 12:24:23 GMT

Mahdi,

Which Packet Tracer are you having trouble with? Please provide an image of the topology, the instructions file, and the Packet Tracer file.

Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Sun, 02 Oct 2022 13:14:24 GMT

Hi Dave thanks for your reply I meant I have uploaded the .pkt from packet tracer above my the last question it's ospftrouble.txt

Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Sun, 02 Oct 2022 13:31:20 GMT

hi Dave I have post the questions with explanation and the entire tasks ,with the issue exactly where exist, I'm doing traineeship in a company but my supervisor he is not helpful man so would you mind helping me try open it in your packet tracer and you will see the problem thanks in advance Dave I really appreciate you help imjust a beginner in this world

Re: Layer 3 Switch cant communicate with Router (PT LAB)

NetworkDave — Sun, 02 Oct 2022 13:45:55 GMT

Mahdi,

There is only a text file that shows output of the running-config. Please attach the actual .PKA or .PKT file along with the instructions. Also, which packet Tracer is it? Example 11.5.6 OSPF?

Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Sun, 02 Oct 2022 14:05:20 GMT

hi dave i have packet tracer 8.1.1 version but i would attach the file .pkt right know and as i said try open it with packet tracer , and the left side of the topology there is three router (router 0, router 1, and router 13 and a switch 3 in between) they are not able to make an ospf connection learn each other even .i m not able to attach the .pkt file in this communoty do you have an email? where can is end the the .pkt format thanks in advance?

Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Sun, 02 Oct 2022 14:24:38 GMT

Ihi dave would you mind do me a favor for making things easier send me your email where i will be able to attach my .pkt tracer tasks because in this comuunity im not able to attach anything .

you sincerley

Mahdi

Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Sun, 02 Oct 2022 15:06:55 GMT

hi dave ihave send you the email with tasks

Re: Layer 3 Switch cant communicate with Router (PT LAB)

NetworkDave — Mon, 03 Oct 2022 08:53:05 GMT

Mahdi,

Solution
--------
On R13, add Sub-interface FastEthernet0/0.5
interface FastEthernet0/0
no ip address 10.5.0.3 255.255.255.0
exit
interface FastEthernet0/0.5
encapsulation dot1Q 5
ip address 10.5.0.3 255.255.255.0

On R13, change ospf 1 network 10.5.0.0 0.0.0.255 to area 1 (from area 0)
router ospf 1
network 10.5.0.0 0.0.0.255 area 1

Verify: show ospf neighbors and show ip route.

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Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Mon, 03 Oct 2022 09:43:04 GMT

hi dave thanks for your solution concerning this part , its work perfectly ospf , but there is one problem i im not able to ping from pc1 to the internet or even to the the router 12 where i got unreachable what is the reason thanks in advance .

your sincelery \mahdi

Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Mon, 03 Oct 2022 13:44:32 GMT

hi dave

im not able to ping from host1 to router and vice versa while the ospf works perfectly do you have any idea about this what would be the main issue?

mahdi

Re: Layer 3 Switch cant communicate with Router (PT LAB)

NetworkDave — Mon, 03 Oct 2022 16:31:27 GMT

Mahid,

Thanks for the update, I'm glad you were able to implement the solution successfully!

You mentioned the internet; There is no internet cloud in this topology?

Please be specific when describing the problem. Examples:
Unable to ping from PC1 to PC7, Unable to ping from R1 to R12., or R13 Link to S3 is will not come up.

There are multiple problems. So, they need to be worked on one by one. The main issue is that some invalid networks are being advertised and some networks are not configured to be advertised. It would be really helpful if there was a list of valid networks and IP address assignments. Please provide the problems that you are aware of...remember, be specific.

I'll be looking into why you can't ping from PC1 to R12

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Re: Layer 3 Switch cant communicate with Router (PT LAB)

NetworkDave — Tue, 04 Oct 2022 09:40:45 GMT

Mahdi,

I've expanded the scope of the problem that you mentioned (PC1 to R12 - Ping failure).

Problem (expanded): No Connectivity from 10.3.x.x to 10.6.x.x / 10.7.x.x / 10.8.x.x networks.
example: PC1 to PC3, PC4, PC5, PC6, and PC7.

Solutions:
Shutdown R12 F0/0 interface
Next hop R2 advertising duplicate networks via OSPF.
Other issues (Ip addressing, links down, etc.)
Configure R1 to advertise 10.3.x.x network.
Assign default gateways on PC6 and PC7
PC6 (10.8.0.253) = Default Gateway 10.8.0.1
PC7 (10.7.0.253) = Default Gateway 10.7.0.1

Connectivity established between 10.3.x.x / 10.6.x.x / 10.7.x.x / 10.8.x.x networks.
example: PC1 to PC3, PC4, PC5, PC6, and PC7.

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Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Tue, 04 Oct 2022 11:34:28 GMT

hi dave

i have a question you said Configure R1 to advertise 10.3.x.x network.

means that i should add this interface (ip address) under the router ospf 1

ospf configuration

your sincerly Mahdi

Re: Layer 3 Switch cant communicate with Router (PT LAB)

NetworkDave — Tue, 04 Oct 2022 11:53:20 GMT

Mahdi,

Configure Router R1 to advertise network 10.3.x.x. via OSPF.
Router(config)#router ospf 1
Router(config-router)#network 10.3.0.0 0.0.0.255 area 1
Router(config-router)#end
Router#

show running-config
!
router ospf 1
log-adjacency-changes
auto-cost reference-bandwidth 1000
network 10.5.0.0 0.0.0.255 area 1
network 10.2.0.0 0.0.0.255 area 1
network 10.3.0.0 0.0.0.255 area 1
!

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Re: Layer 3 Switch cant communicate with Router (PT LAB)

mahdi benameur — Tue, 04 Oct 2022 13:08:01 GMT

hi dave

thanks for your help

when i wrote show ip route i didn t see any ospf changement .

i see only this

Router#show ip ro

Router#show ip route

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

* - candidate default, U - per-user static route, o - ODR

P - periodic downloaded static route

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 8 subnets, 2 masks

C 10.2.0.0/24 is directly connected, GigabitEthernet0/0/0.2

L 10.2.0.253/32 is directly connected, GigabitEthernet0/0/0.2

C 10.3.0.0/24 is directly connected, GigabitEthernet0/0/0.3

L 10.3.0.253/32 is directly connected, GigabitEthernet0/0/0.3

C 10.4.0.0/24 is directly connected, GigabitEthernet0/0/0.4

L 10.4.0.253/32 is directly connected, GigabitEthernet0/0/0.4

C 10.5.0.0/24 is directly connected, GigabitEthernet0/0/1.5

L 10.5.0.4/32 is directly connected, GigabitEthernet0/0/1.5