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New Member

Port trunking on SLM2024

I have a couple SLM2024s that I need to configure with a few VLANS that allow communication between specific VLANS.  I think I understand how to do this, except for the connection to the router.  It is my understanding that I need to configure the port to the router as a Trunk port.  However, I can't figure out how to do this in the SLM2024.  Does it not support port trunking?

Edit: Or am I completely wrong in thinking I need to configure the port to the router as a trunk?  Can I configure communication between VLANs without port trunking?

2 ACCEPTED SOLUTIONS

Accepted Solutions
New Member

Re: Port trunking on SLM2024

WebEx sounds great. Our number here is 866.606.1866. You will need to have two things, your Cisco.com login ID (aka CCOID) and your serial number. You can ask for me directly if you wish.

Regards,

Christopher

New Member

Re: Port trunking on SLM2024

Hello,

Removing VLAN 1is not something I would recommend. You can however enable filers that will require ingress traffic to have a tag, which will prevent VLAN 1 traffic from successfully passing. Please understand that the management IP address of the unit is on VLAN 1, and if you cut all access off for VLAN 1, you will render the switch (SLM) unreachable and a factory default reset will be required to make any changes.

VLAN1 is the only untagged VLAN (though you can break this rule if you must). All the other VLANs must be tagged. When the switch receives the frames, it must be able to differentiate which frames belong to which VLAN. It does this by looking at the number on the tagged frame. In the case of VLAN1, what makes it unique in the mind of a switch, is that it has no tag at all. In the case of these small business series devices, these untagged frames are then sent to the PVID of the switchport. So, while being an untagged frame is unique, it is not very descriptive and we must tell the switch exactly what to do with it.

I hope this helps. Let me know if I can clarify anything else.

Regards,

Christopher

PS mortalwombat was correct

11 REPLIES
New Member

Re: Port trunking on SLM2024

Hi,

I have attached a document that should help you set up your trunk if your using version 1.0.1 firmware. The part that is of interest to you starts on page 7. This would be a very easy fix over the phone with a webex session though. to answer your questions though, yes this switch supports trunks. Setting up a trunk to your router is probably your best bet for intervlan routing. Yes there are other ways to set this up, including port based VLANs (high port density cost) and layer three switching (with a compatible switch).

Regards,

Christopher

New Member

Re: Port trunking on SLM2024

I am running version 1.0.1 on my switch, but am not seeing the same options that I see in the document you attached.  Most notably, under VLAN Management/Port settings, I do not seem to have any options for "Mode" which is where your document say's I should change the port to a trunk.  I even tried creating a LAG that I assigned the port to, just to be consistent with the document you provided.  Even still, trunk is not available.

Also interesting is that on page 9 of your document, the "Acceptable Frame Type" area is not available.  All I have is membership for the ports and LAGs with "Tagged" "Untagged" or "Excluded".

I would love to do a webex to help sort this out.  How can I set that up?

New Member

Re: Port trunking on SLM2024

WebEx sounds great. Our number here is 866.606.1866. You will need to have two things, your Cisco.com login ID (aka CCOID) and your serial number. You can ask for me directly if you wish.

Regards,

Christopher

New Member

Re: Port trunking on SLM2024

Hi,

  I'm trying to achieve a very similar thing, to create a VLAN trunk between a pair of cisco SLM2024 switches.

Did you resolve this and if so, what steps did you follow to create the VLAN trunk?

Under VLAN Management > Port to VLAN, do I simply add each of the  required VLAN's (Default VLAN 1, VMware ESX Service Console VLAN 9, iSCSI VLAN 100 & Management VLAN 101 in this instance) as tagged to the uplink port on each of the switches?

The end configuration will be LAG using two ports per switch with VLAN trunk between the switches.

Regards,

     Protegimus

New Member

Re: Port trunking on SLM2024

With Chris's help over webex, we got a good start and he did a great job of explaining the way this works.  We should be talking some more today so I hope to have an even better understanding after that.  With the SLM series switches, the Trunk option is not selectable, but is handled automatically.  I think I have a pretty good grasp on what you would do for this, but maybe Chris can correct me if I am wrong.

First, create your LAG and join the appropriate ports to it.  Once that is done, move to the VLAN management tab and move to the third page where the LAGs are shown.  Make sure the PVID is set to 1.

Then click VLAN to Port and go to the third page where your LAGs are shown.  Click Join VLAN for the apropriate LAG.  Then add the appropriate untagged VLANs.

Make the same settings on the second switch.  Keep in mind it is important that both switches are configured for the same VLAN IDs.

I hope I got this right, and I hope this helps.

New Member

Re: Port trunking on SLM2024

Thanks for the information mortalwombat, much appreciated.

I have one or two questions that I hope you can provide more information about (the switches we have are in use, so I want to investigate as far as possible before putting the change request in):

The LAG should be assigned VLAN ID 1, the default VLAN - can VLAN 1 be subsequently removed from the trunk if it is not required?

Please can you clarify that I should then add 'untagged' VLAN's to the LAG, to create my trunked link? I ask because my experience with cisco has been with IOS and also HP ProCurve on managed switches; where you would usually tag the frames on a trunked link in IOS using switchport trunk encapsulation dot1q

Thanks & regards,

     Protegimus

New Member

Re: Port trunking on SLM2024

Hello,

Removing VLAN 1is not something I would recommend. You can however enable filers that will require ingress traffic to have a tag, which will prevent VLAN 1 traffic from successfully passing. Please understand that the management IP address of the unit is on VLAN 1, and if you cut all access off for VLAN 1, you will render the switch (SLM) unreachable and a factory default reset will be required to make any changes.

VLAN1 is the only untagged VLAN (though you can break this rule if you must). All the other VLANs must be tagged. When the switch receives the frames, it must be able to differentiate which frames belong to which VLAN. It does this by looking at the number on the tagged frame. In the case of VLAN1, what makes it unique in the mind of a switch, is that it has no tag at all. In the case of these small business series devices, these untagged frames are then sent to the PVID of the switchport. So, while being an untagged frame is unique, it is not very descriptive and we must tell the switch exactly what to do with it.

I hope this helps. Let me know if I can clarify anything else.

Regards,

Christopher

PS mortalwombat was correct

New Member

Re: Port trunking on SLM2024

One thing I was not clear on in my response, which I verified this morning, is the tagging on the trunk.

On your trunk, set the PVID to 1, then in VLAN to Port, set VLAN 1 to untagged and all your other VLANs to Tagged.  This creates a unique tag for every VLAN.  VLAN 1 will be unique in the fact that it is the only VLAN without a tag.  If your frames have a tag assigned to them, they will go to the specific VLAN, or if there is no tag, they will go to VLAN 1.  Does that make sense?

New Member

Re: Port trunking on SLM2024

Thanks for the reply gents, that does clarify things.

Also, interesting information Christopher thanks, though I was simply asking about removing VLAN 1 from the inter-switch VLAN trunk, not all ports on the switch.


Another question you will know the answer to, when you configure the LAG, is traffic between the switches interrupted for this short period, or is it not affected?

Regards,

     Protegimus

New Member

Re: Port trunking on SLM2024

Traffic IS interrupted for a very brief period of time. This is due to the "human latency" effect of configuring both sides of the LAG. If you set up the switches to use LACP that time is shortened, and the users should not know that a LAG was created. The negotiation via LACP is very quick (< 3-5 seconds) and once both switches agree on a LAG it will continue to forward the traffic accordingly.

Bottom line, the users will not really notice the "network down" state unless on a VoIP call at the time of the configuration. As a courtesy, let every user know (usually via email) that network maintenance it being performed, and if they experience any issues, wait about 5 minutes before being concerned.

Bill

New Member

Re: Port trunking on SLM2024

Thanks for all the information and rapid replies, most helpful.

Environment is under change control, that's why I was confirming expected impact and  user notification is a formality, but good advice anyway!

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