DHCPv6 stateful configuration on multilayer switch 3650

matzki · ‎07-12-2023

hello,

my name is martin and i am trying to configure a multilayer switch in packet tracer 8.2 for a project in openclassroom.

i have searched the internet but i cannot find any relevant information. so you are my last hope. there is plenty of information how to do it with a router (which i succeed to configure) but not on a L3switch.

For explanation : there is a lan with 1 router isr4331 and 3 L3 switchs (3650). on 2 of the switches i have to configure dhcp and dhcpv6 (stateful). the dhcpv4 configuration is no probleme, but my dhcpv6 configuration on the layer 3 switch (Multilayer Switch3-2) doesen't seem to be effective. the clients continue to receive theire address from the router (i think it is called slaac) and ignore my dhcpv6 configuration. i am joining the configuration files for the router and the concerned switch.

There is no special configuration to do, i just want to assigne dhcpv6 addresses and dns server with stateful addressing to my clients.

i am very desperate because i try to resolve this since 2 month. maybe i am just missing one little detail. any help is realy appreciated.

I am sorry for my bad english, it is not my first language (answers in german and french are also welcome). many thanks in advance, martin

Flavio Miranda · ‎07-13-2023

Hi @matzki

Can you share your PacketTracer Project? It would be easier and it would be a opportunity to test in a another computer. It can be a problem in your file.

You need to zip the pkt file first

matzki · ‎07-13-2023

Helo Flavio,

thank you for answering me. here is my project. i am out this afternoon because i have some appointements. i will check back later.

martin

Flavio Miranda · ‎07-13-2023

Hey @matzki

Well, sorry if I misunderstood your project but I am considering that the PC 0 connect to the switch SW_COMRH was the test PC.

When I first opened the PC, it had no IP whatsoever.

then, I saw that the PC interface on the switch was in trunk.

After changing that, I got both IPv4 and IPv6 via DHCP

Please, let me know if the problem was something else and I understood wronly. If so, we can try to troubleshooting it together.

matzki · ‎07-13-2023

Hi @Flavio Miranda

I'm sorry if my explanations weren't very clear

1. You considered right in that the PC 0 is my test pc. I connect it to the different switches to test all the vlans (10, 20, 30, 40).

2. It is very strange that the switch port is in trunk mode, because here it really is in access mode for vlan 40. I rechecked the copy i've joined earlier.

3. There is no probleme with dhcp IPv4. After loading the file it takes a while for dhcp to take effect. during this time dhcp ip4 is using an appia address.

4. It is the DHCPv6 which is not working proberly. In your screenshot you can see that there is no dns server assigned but it is configured on switch 3-2 for all vlans. I believe that the client ipv6 address is configured with slaac via the router interface and not via the dhcp configured on switch 3-2.

5. the "ipv6 nd managed-config-flag" (which should told the client to use dhcpv6 stateful configuration) activated on vlan interface on switch 3-2 creates an instability on the network which causes loss and reassignemnt of the dhcpv6 address. Look also at the value of the default gateway (....8801=router, ......7602=switch)

6. I can get a dns server with "ipv6 nd ra dns server 2001:0:CAFE:50::3" configured on the subinterface (p. e. : 0/0/0.40) of the router4.

But it still ignores my dhcpv6 configuration on layer 3 switch 3-2.

So if you (or somebody else) could explaine to me how to get DHCPv6 stateful configuration work on a layer3 switch with a router in the same network, it would considerably brighten up my day :-).

Flavio Miranda · ‎07-13-2023

Hi @matzki

Well, I may not brighten too much your day but I will shed some light!

The problem is the Layer3 switch. As you can see below, I manage it to work on the router instead. And that because the router have the command "ipv6 nd ra dns server x.x.x.x" that you can add to the interface which will provide the DHCP/DNS.

This command does not exist on the Layer3 switch.

matzki · ‎07-13-2023

Hello @Flavio Miranda ,

I am also getting to the conclusion that the multilayer switch 3650 in packet tracer cannot be configured with dhcpv6 stateful configuration. Also i am asking me, why one can create a dhcpv6 pool and assigne it to a vlan interface with "dhcpv6 stateful' option activated if it does not work. I tested it with 1 router, 1 normal switch and 1 pc in a new file and without the "ra dns server"-option and it is functionning like it should. I joined the configuration files of router and switch. But the same configuration with a L3 switch does not work.

So at this point i am giving up and i will use the router for dhcpv6 configuration in my project. I will also write a message to openclassroom, demanding them to share the secret of how to accomplish this task.

Thank you so much for trying to help me and the time you spent on the probleme.

Flavio Miranda · ‎07-14-2023

Actually it works except for deliverimg dns.

Yeah, PacketTracer has limitations. Yet it is very handfull.

Good luck with your study