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LAG/LACP with Multiple VLANS

Hi there,

I have two SG-200-50 switches. I have created three VLANS on one and set the same up on the other - there is no requirement for routing between the VLANS. However, I would like to trunk between the VLANS using LAG with LACP. For example Switch A ports 1-22 are VLAN 1 and then 23-24 is the trunking for this. 25-34 is VLAN2 and trunking is 35-36. VLAN 3 is 37-48 and trunking 49-50. I seemed to be able to get VLAN 1, the default, trunking but not VLAN 2.

I have some questions:

1. Will the SG-200 allow you to trunk multiple VLANS to another switch?

2. If it does - how? I have been through the documentation and it doesn't explicitly mention 'multiple' VLANS with LAG.

3. Is trunking possible through one LAG (say 6 ports) which passes all VLANS on the switch?

So the primary question is whether what I want to achieve is possible on this switch. The reason I am trying to do this is of course redundancy. Carrying a VLAN over two switches is better. I just need to trunk properly between these.

Cheers! Any thoughts appreciated.

scott

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1 ACCEPTED SOLUTION

Accepted Solutions
Highlighted
Rising star

Re: LAG/LACP with Multiple VLANS

Hi Scott,

You had some  questions, which I have copied in red.:

1. Will the SG-200 allow you to trunk multiple VLANS to another switch?  Absolutely

2. If it does - how? I have been through the documentation and it doesn't explicitly mention 'multiple' VLANS with LAG.

I have attached the Admin guide.  The rules for LAG are defined at the bottom of page 82 of the attached document.

The 200 series supports four LAGs or in other words four Link aggregagted groups. 

3. Is trunking possible through one LAG (say 6 ports) which passes all VLANS on the switch?  Yes as the Admin guide suggests of page 83 , "

Assign up to eight active member ports to the static LAG"

So the primary question is whether what I want to achieve is possible on this switch. The reason I am trying to do this is of course redundancy. Carrying a VLAN over two switches is better. I just need to trunk properly between these.

I personally prefer to trunk over lags a different way, especially since you are only trying to achieve redundancy and higher aggregated bandwidths between switches.  This is also relevant to the 300 series as the 300 series product is just a more feature rich product.

You want to ;"I would like to trunk between the VLANS using LAG with LACP. For example Switch A ports 1-22 are VLAN 1 and then 23-24 is the trunking for this. 25-34 is VLAN2 and trunking is 35-36. VLAN 3 is 37-48 and trunking 49-50. I seemed to be able to get VLAN 1, the default, trunking but not VLAN 2."

What about using the higher number ports for uplinking between switches, I have no particular reason for using these ports except they are on the right side of the switch.

                    Switch A                Switch B

                     ports                   ports

vlan 1               1-24,47-48              1-24,47-48

vlan2                25-34                   25-34

vlan3                35-46                   35-46

LAG ports            49-50                   49-50

The advantage of this is that now you have two ports load balancing traffic between the  two 200 series switches.  I could have more if i want, but i want to keep my example simple.

Create a Static LAG, by the sound of it you've done this already.

I just used my 300 series (SF300-48p)switch as a demo, as i don't have a 200 series switch.  Configuration should just about be just about identical.  In my case I have four GiG ports GE1 to GE4.  I will use GE1 and GE2 as my two members of a LAG group 1.  Might sound a bit confusing , but follow along below.

Added two ports to the LAG, note in the example below GE1 and GE2  are not connected to another switch , so they showup as standby ports;

Also my 300 series switch supports eight LAG groups, hence the numbers 1 to 8 as shown in subsequent screen captures.


Now that my LAG is created, you will note in the screen capture below that, VLAN1 is added automatically to LAG 1 as untagged frames.

Note: the circled Item, I selected LAG from that drop down menu and then clicked Go.

Note: 1 in the red rectangular box represents LAG group 1,  which is made up of GE1 and GE2

Now I add VLAN 2 to the LAG group 1 by  selecting VLAN 2 then selected LAG and then clicked go, the following screen came up.

I clicked on the tagged radio button in the rectangle above,  to allow VLAN 2 to send tagged ethernet frames over the LAG group 1.

And so on ,  for other VLANs i migth have.

My methodology or train of thought, was to allow vlan1 to just send untagged frames over the LAG group 1,  but any other subsequent  VLANs will be tagged over the LAG group 1.

You should be able to do exactly the same thing on the other 200 series switch.

in my example I then just grab  a couple of CAT6 or CAT5e cables and connect GE1 on one 200 series switch to Ge1 on the other 200 series switch

I then connect GE2 on one 200 series switch to Ge2 on the other 200 series switch.

Now I have Link aggregation and load balancing working between switches.

Hope this helps

regards Dave

View solution in original post

9 REPLIES 9
Highlighted
Rising star

Re: LAG/LACP with Multiple VLANS

Hi Scott,

You had some  questions, which I have copied in red.:

1. Will the SG-200 allow you to trunk multiple VLANS to another switch?  Absolutely

2. If it does - how? I have been through the documentation and it doesn't explicitly mention 'multiple' VLANS with LAG.

I have attached the Admin guide.  The rules for LAG are defined at the bottom of page 82 of the attached document.

The 200 series supports four LAGs or in other words four Link aggregagted groups. 

3. Is trunking possible through one LAG (say 6 ports) which passes all VLANS on the switch?  Yes as the Admin guide suggests of page 83 , "

Assign up to eight active member ports to the static LAG"

So the primary question is whether what I want to achieve is possible on this switch. The reason I am trying to do this is of course redundancy. Carrying a VLAN over two switches is better. I just need to trunk properly between these.

I personally prefer to trunk over lags a different way, especially since you are only trying to achieve redundancy and higher aggregated bandwidths between switches.  This is also relevant to the 300 series as the 300 series product is just a more feature rich product.

You want to ;"I would like to trunk between the VLANS using LAG with LACP. For example Switch A ports 1-22 are VLAN 1 and then 23-24 is the trunking for this. 25-34 is VLAN2 and trunking is 35-36. VLAN 3 is 37-48 and trunking 49-50. I seemed to be able to get VLAN 1, the default, trunking but not VLAN 2."

What about using the higher number ports for uplinking between switches, I have no particular reason for using these ports except they are on the right side of the switch.

                    Switch A                Switch B

                     ports                   ports

vlan 1               1-24,47-48              1-24,47-48

vlan2                25-34                   25-34

vlan3                35-46                   35-46

LAG ports            49-50                   49-50

The advantage of this is that now you have two ports load balancing traffic between the  two 200 series switches.  I could have more if i want, but i want to keep my example simple.

Create a Static LAG, by the sound of it you've done this already.

I just used my 300 series (SF300-48p)switch as a demo, as i don't have a 200 series switch.  Configuration should just about be just about identical.  In my case I have four GiG ports GE1 to GE4.  I will use GE1 and GE2 as my two members of a LAG group 1.  Might sound a bit confusing , but follow along below.

Added two ports to the LAG, note in the example below GE1 and GE2  are not connected to another switch , so they showup as standby ports;

Also my 300 series switch supports eight LAG groups, hence the numbers 1 to 8 as shown in subsequent screen captures.


Now that my LAG is created, you will note in the screen capture below that, VLAN1 is added automatically to LAG 1 as untagged frames.

Note: the circled Item, I selected LAG from that drop down menu and then clicked Go.

Note: 1 in the red rectangular box represents LAG group 1,  which is made up of GE1 and GE2

Now I add VLAN 2 to the LAG group 1 by  selecting VLAN 2 then selected LAG and then clicked go, the following screen came up.

I clicked on the tagged radio button in the rectangle above,  to allow VLAN 2 to send tagged ethernet frames over the LAG group 1.

And so on ,  for other VLANs i migth have.

My methodology or train of thought, was to allow vlan1 to just send untagged frames over the LAG group 1,  but any other subsequent  VLANs will be tagged over the LAG group 1.

You should be able to do exactly the same thing on the other 200 series switch.

in my example I then just grab  a couple of CAT6 or CAT5e cables and connect GE1 on one 200 series switch to Ge1 on the other 200 series switch

I then connect GE2 on one 200 series switch to Ge2 on the other 200 series switch.

Now I have Link aggregation and load balancing working between switches.

Hope this helps

regards Dave

View solution in original post

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LAG/LACP with Multiple VLANS

That's fantastic. Just what I was looking for and it works perfectly. A trunk by switch as opposed to each VLAN is a better idea. Many thanks, much appreciated.

Scott

Highlighted
Beginner

LAG/LACP with Multiple VLANS

Is it possible to create a LAG trunk to two different switches?

I have two Cat4948s as L3 backbone using HSRP. I'd like to connect one SG-200 50 to both of them, trunking all VLANs.

Highlighted
Advocate

LAG/LACP with Multiple VLANS

Hi Sfabel, HSRP is unsupported. You would need to use a static LAG. channel-group mode on

-Tom
Please rate helpful posts

-Tom Please mark answered for helpful posts http://blogs.cisco.com/smallbusiness/
Highlighted
Beginner

LAG/LACP with Multiple VLANS

Hi Tom,

thanks for your answer. Not sure if I didn't explain right or whether I'm not following you. I'll try again...

I have two Cat4948s that do HSRP for all VLANs. They are load-balanced (i.e. they have alternating standby priorities across the spectrum of the VLANs). I'm now trying to attach an SG-200 50 to these switches. The idea is to create a (manual) LAG on the SG-200, and connect one cable to one, the other to the other 4948, and trunk all the VLANs across the LAG.

My experience is that the link on the LAG remains down when I attach both cables.

Is there something special I need to do? For example, do I need to activate LACP?

http://en.wikipedia.org/wiki/Link_aggregation#Limitations seems to suggest that there are vendor extensions that allow these kinds of deployments, although there's no mention of Cisco.

Thanks,

Stephan

Highlighted
Advocate

LAG/LACP with Multiple VLANS

The SX200 series is oblivious to HSRP. It also does not support PVST, PVST+ OR RPVST. Additionally, the SX200 series does not support MSTP.

How I understand your statement is you are running HSRP on 2 Catalyst. You would like to have 2 uplinks from the SG200.  Catalyst A connects to SG200 with 1 link. Catalyst B connects to SG200.

I am assuming your IST would force one of the ports into blocking state to prevent looping and enforce a correct spanning-tree topology.

802.1q and CST/RSTP rules will apply here. LACP is not needed as this is not a LAG situation. If it were a LAG situation, I would use a static LAG between Catalyst switches and the SB switches (channel-group mode on). A misconfiguration of LACP from any of the switches would result in a spanning-tree loop and likely bring down the SX200, therefore a static LAG would be the most conversative.

-Tom
Please rate helpful posts

-Tom Please mark answered for helpful posts http://blogs.cisco.com/smallbusiness/
Highlighted
Rising star

Re: LAG/LACP with Multiple VLANS

Hi Stephan,

Toms spot on, even though the Cat4948 is a real beast with lots of functionality built in, it does not supported STACKING between the 4948. 

When you "stack" two or more switches together, like with the Sx500, 2960S, 3750X.  ...all switches in a stack act as a single switch unit. The Cisco Stack provides a unified data plane, unified configuration, and single IP address management for a group of switches. .This then allows for adding a LAG between switches in a stack. So a LAG as shown below to a STACK of switches will work

If the CAT 4948 supported Stacking you could LAG a SG200 between the stacked switches, because a LAG group only works between one switch to another.  With the case of a "stacking" switch, the switches in a stack appear/behave as one switch .

Since the 4948 doesn't support stacking, Tom is dead right, in your case you really  have two distinct CAT4948 switches wired together.

If you then decide to  link to each CAT4948 from the SG200 switch, but you will need Rapid Spanning tree running on the switches to block one of the GbE links from the SG200 or a loop will result.  If spanning tree or the variant Rapid spanning tree isn't used  a broadcast storm will surely result.

The bottom line is, LAG from the SG200 will not work to the CAT4948, the way you would like  it to work..

regards Dave

Highlighted
Beginner

Re: LAG/LACP with Multiple VLANS

Thanks guys for your awesome insight. I assumed that spanning tree would take care of that. So this basically should work *if* I just configure both ports to be identical trunks. If one 4948 goes down, rapid spanning tree will open the other trunk, and connectivity will be restored. No LAG possible, but also not needed for redundancy purposes.

Highlighted
Rising star

Re: LAG/LACP with Multiple VLANS

Hi Stephan,

I think you now appreciate how it would work, great. 

Thank you for your purcahses.

regards Dave