Getting DHCP through Dell 6224 VLANs

The routing commands look good, but it sounds like there may be a misunderstanding of how the different switchport modes are used. I will outline the basics here.

Access Links connect VLAN unaware devices to the port of a VLAN-aware switch. All frames on access links are untagged. The VLAN switch adds tags to received frames, and removes tags when transmitting frames. End users and VLAN-unaware workstations commonly reside on access links.By Default all ports are in ACCESS mode assigned to the default VLAN (VLAN 1). Ports set to Access mode belong to one VLAN only.

Trunk Links attach two VLAN aware switches (or other VLAN aware devices) together and allows for multiple VLAN frames to cross one link. On VLAN trunk links, all frames must be tagged with the respective VLAN ID’s The native VLAN must match on all switches in the segment. (VLAN 1 is default Native VLAN).  The native VLAN is NOT tagged.

Default behavior: An interface placed into trunk mode on the PowerConnect 62xx will drop all untagged traffic, including default VLAN 1 untagged traffic, and will permit tagged traffic from multiple VLANs to pass.  As with general mode, the additional tagged VLANs must be explicitly defined on the interface.

General Links consist of a combination of VLAN Trunk and Access Links.

General Links can have both tagged and untagged frames, However, all frames sent to a specific VLAN must be tagged.  All untagged  frames are sent to the native VLAN.The native VLAN still applies to the General LINK.  While it is possible to have multiple untagged vlans on a General link, you can only have ONE (1) PVID.  The PVID represents the native VLAN. While untagged traffic may be sent via several untagged VLANs, returning untagged traffic will only be received by the PVID and therefore will NOT be forwarded to a specific VLAN.General links are mostly used today for legacy equipment.  However, on the PowerConnect 62xx series switches, you must use General mode if you want to allow management traffic onto the switch over the PVID.  If you use Trunk mode, you will not have the default VLAN on those ports.  The ports will only allow tagged traffic.

With this information in mind, I would suggest the following.

1. It sounds like you have three separate connections from switch to switch, using access mode? It is fine to have three physical connections from switch to switch, but those connections should probably be set into a LAG, and then that LAG set to General mode allowing the specific VLANs across it. Something similar to the following.

console(config)# interface range ethernet 1/g1-3

console(config-if)# channel-group 1 mode on

console(config)# interface channel-group 1

console(config-if)# switchport mode general

console(config-if)# switchport general allowed vlan add 10,20,30 tagged

console(config-if)#  switchport general pvid 2

2. Each laptop, desktop, and server should be on a port that is in access mode for a specific VLAN. Unless the server has a virtual switch with VLANs on it. If there is no virtual switch on the server, then it is sending out untagged traffic, and in a general port that untagged traffic will just go onto the PVID.

3. To access the management web gui you will use the IP address assigned to the management VLAN, which looks to be 172.16.1.254

Here is a good article that talks more about VLAN routing and setup.

www.dell.com/.../app_note_38.pdf

Side note, it is always a good idea to keep the switch firmware up to date, it can help ensure things run as smooth as possible.

62xx firmware

www.dell.com/.../powerconnect-6224

2724 firmware

www.dell.com/.../powerconnect-2724

Hope you find this information helpful, keep us updated.

Thanks.

Thank you for the information this is very helpful.

A couple more questions.

In the Article you sent above in the Step by Step instructions #4 says:

Define routes to each network.

Dell-6024(config)# ip route 10.10.0.0 255.255.255.0 10.10.0.2

Dell-6024(config)# ip route 10.20.0.0 255.255.255.0 10.20.0.2

Can you explain this?  Where did the 10.10.0.2 and 10.20.0.2 addresses come from?

Then also in that article it says:

we assume the router has previously been configured to reach the DHCP server on the

10.100.0.0/24 subnet.

However this is the part I need help with.

In my domain controller I have DHCP setup with 3 scopes, one for each VLAN.  I will be connecting this server directly to the 6224.  How do I need to setup the port that this server is connected to?  From what I had read on other posts I was under the impression that this port needed to be tagged (or trunked?) and setup with all 3 VLANs.  Is that wrong?

Thanks.

a static route is a way to define a  path in the router that specifies how the router will get to a certain subnet by using a certain path.

Looking at the command

ip route 10.20.0.0 255.255.255.0 10.20.0.2

The first address 10.20.0.0 is the destination address

255.255.255.0 is the subnet

And the last address is 10.20.0.2 is the next-hop

With one DHCP server servicing multiple VLANs, that is where the ip helper-address comes into play. Which you already have in place.

Page 555 of the configuration guide goes into this some more.

support.dell.com/.../ucg_en.pdf

The DHCP server should be placed on an access port. Unless you have a virtual switch configured on the server, or some other method of tagging the traffic coming from the server, plugging a server into a general port will result in that port receiving untagged traffic from the server and then placing it on the PVID. So even thought you have that port set to general mode with VLANs 10,20,30 added, the server is not directly communicating with those VLANs.

Layer 2 functionality of this would be DHCP l2relay.

Page 461

support.dell.com/.../ucg_en.pdf

Thanks.

On the DHCP Server.  First, if I put this on an Access port, it only allows me to put it on one VLAN, is that ok?

Then I read the information on the DHCP l2relay, and I understand that I need to turn it on globally, but which individual ports do I need to enable it on?  Just the one with server attached?  Or do I also need to enable it on the port that connects to the layer 2 switch?  Or do I need to turn it on, on the layer 2 switch?

Thanks.

By the way....i have the same setup, but I reset my switch and started over....here is my new running-config:

console#show running-config

!Current Configuration:

!System Description "PowerConnect 6224, 3.3.4.1, VxWorks 6.5"

!System Software Version 3.3.4.1

!Cut-through mode is configured as disabled

!

configure

vlan database

vlan 2,10,20,30

vlan routing 10 1

vlan routing 20 2

vlan routing 30 3

exit

stack

member 1 1

exit

ip address 172.16.1.254 255.255.255.0

ip address vlan 2

ip routing

ip helper-address 172.16.10.10 dhcp

interface vlan 10

routing

ip address 172.16.10.254 255.255.255.0

exit

interface vlan 20

routing

ip address 172.16.20.254 255.255.255.0

exit

interface vlan 30

routing

ip address 172.16.30.254 255.255.255.0

exit

username "admin" password 80f3be0c63f2722b4293c531e1e7a09f level 15 encrypted

dhcp l2relay

!

interface ethernet 1/g1

dhcp l2relay

switchport access vlan 10

exit

!

interface ethernet 1/g24

dhcp l2relay

switchport mode trunk

switchport trunk allowed vlan add 10,20,30

exit

exit

console#

Here is a very quick drawing of my setup:

Yes it is fine that  the DHCP server is on one VLAN. The server sends out untagged traffic, which when received by a general port, the general port places the untagged traffic onto the PVID. So no matter how many VLANs the general port participates in, the server traffic will always go on the PVID since it is not tagged. Because of this we are simplifying things and setting the port to access mode for a specific VLAN.

Then VLAN routing enables the different VLANs to communicate with each other.

Were you able to get this working as desired? Any updates?

Thanks

No I have not been able to get this to work.  In fact I think I screwed it up more.

I am actually unable to communicate between my switches now.  If you see my drawing above, I removed the three connections I had from the 6224 and the 2724 and replaced them with one connection.  The port on either end of this connection is set to Trunk with all three VLANs.  But I put one of the Laptops on the 2724 with a static address and I cannot ping it from the switch.

Should I have left the 3 connections from the 6224 to the 2724?  

When doing ping tests, it is always a good idea to start small and work out to find the point of dropped communication. So start with trying to ping the switch the laptop plugs into. So if the laptop plugs into the 2724, make sure that communication is good, then try to ping the next switch 6224, then try to ping the server. From what you said it sounds like the communication is dropping off when trying to communicate from one switch to the next.

I am still not seeing any static routes being put in place. I would recommend getting that added in to the configuration. Then test for connectivity.

Side note-PowerConnect 62xx series switches, you must use General mode if you want to allow management traffic onto the switch over the PVID.  If you use Trunk mode, you will not have the default VLAN on those ports.  The ports will only allow tagged traffic.

I added in the Static Routes, but still have no connectivity between the two switches.

From the 6224, I can ping the Server, and I can ping all my "Gateway" addresses (i.e. 172.16.20.254).  But I still cannot see the system on the 2724.  And from the 2724 I can't ping anything.

Here is my current config:

console#show running-config

!Current Configuration:

!System Description "PowerConnect 6224, 3.3.4.1, VxWorks 6.5"

!System Software Version 3.3.4.1

!Cut-through mode is configured as disabled

!

configure

vlan database

vlan 2,10,20,30

vlan routing 10 1

vlan routing 20 2

vlan routing 30 3

exit

stack

member 1 1

exit

ip address 172.16.1.254 255.255.255.0

ip address vlan 2

ip routing

ip route 172.16.10.0 255.255.255.0 172.16.10.2

ip route 172.16.20.0 255.255.255.0 172.16.20.2

ip route 172.16.30.0 255.255.255.0 172.16.30.2

ip helper-address 172.16.10.10 dhcp

interface vlan 10

routing

ip address 172.16.10.254 255.255.255.0

exit

interface vlan 20

routing

ip address 172.16.20.254 255.255.255.0

ip helper-address 172.16.10.10 dhcp

exit

interface vlan 30

routing

ip address 172.16.30.254 255.255.255.0

ip helper-address 172.16.10.10 dhcp

exit

username "admin" password 80f3be0c63f2722b4293c531e1e7a09f level 15 encrypted

dhcp l2relay

!

interface ethernet 1/g1

dhcp l2relay

switchport access vlan 10

exit

!

interface ethernet 1/g24

switchport mode trunk

switchport trunk allowed vlan add 10,20,30

exit

exit

console#

On the 2724 the connection from the 6224 is in port 24, which I have set to Tagged for all three VLANs.

Still no connection.

The Laptop is set to:

IP - 172.16.20.20

SubNet - 255.255.255.0

Gateway - 172.16.20.254

Here are some images from the 2724:

And here is the latest Running Config:

console#show running-config
!Current Configuration:
!System Description "PowerConnect 6224, 3.3.4.1, VxWorks 6.5"
!System Software Version 3.3.4.1
!Cut-through mode is configured as disabled
!
configure
vlan database
vlan 2,10,20,30
vlan routing 10 1
vlan routing 20 2
vlan routing 30 3
exit
stack
member 1 1
exit
ip address 172.16.1.254 255.255.255.0
ip address vlan 2
ip routing
ip route 172.16.10.0 255.255.255.0 172.16.10.2
ip route 172.16.20.0 255.255.255.0 172.16.20.2
ip route 172.16.30.0 255.255.255.0 172.16.30.2
ip helper-address 172.16.10.10 dhcp
interface vlan 10
routing
ip address 172.16.10.254 255.255.255.0
exit
interface vlan 20
routing
ip address 172.16.20.254 255.255.255.0
ip helper-address 172.16.10.10 dhcp
exit
interface vlan 30
routing
ip address 172.16.30.254 255.255.255.0
ip helper-address 172.16.10.10 dhcp
exit
username "admin" password 80f3be0c63f2722b4293c531e1e7a09f level 15 encrypted
dhcp l2relay
!
interface ethernet 1/g1
dhcp l2relay
switchport access vlan 10
exit
!
interface ethernet 1/g24
switchport mode general
switchport general pvid 2
switchport general allowed vlan add 10,20,30
exit
exit

console#

I would change the Trunk mode to General mode and set the PVID to the management VLAN which looks like you changed to VLAN 2.

switchport mode general

switchport general allowed vlan add 10,20,30

switchport general pvid vlan 2

Can you show us some screen shots of the 2724 vlan and port settings?

Then From the 6224 console can you ping the 2724 address? What are the static settings on the laptop?

Thanks

These port configurations look good. Lets look at the following.

1. From the 6224 console, can you ping the 2724 switch itself, not the laptop but the actual IP address of the 2724.

2. From the server on the 6224 can you ping the 6224?

3. From the server on the 6224 can you ping the 2724 IP address, not the laptop, but the switch itself.

4. On the laptop connected to the 2724, the gateway is set to 172.16.20.254, is that the VLAN 20 IP address on the 2724?

5. If you move the laptop to the 6224, can it ping the DHCP server?

Thanks