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aetius80

1 Rookie

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34 Posts

33947

August 20th, 2013 06:00

Configuring a LAG between stacked 6000 and stacked 5000 switches

Hi,

I have:

2 x 6000 PowerConnect (PC) switches - stacked, let’s call these 6PC_Unit1 &
6PC_Unit2

2 x 5000 PC switches - stacked, let’s call these 5PC_Unit1 & 5PC_Unit2

These switches have multiple VLANS

I want to create a LAG between these switches.Please advise if I've got
anything wrong, but my plan is to do the procedure below.

On
6PC_Unit1 run:


  1. Sw(config#) Interface te1/0/1, te1/0/2, te1/0/1, te1/1/2 (select
    ports1 & 2 on both stack members)

  2. Sw(config-if#) channel-group 1 mode active (enable ports with LACP,
    dynamic)

  3. Show interfaces port-channel 1 (confirm interfaces are in the port
    channel)

  4. Interface port-channel 1

  5. Switchport mode trunk
  6. Switchport trunk allowed vlan add 1,10,20,30 tagged

  7. switchport trunk allowed vlan add 10,30 tagged

Do the above procedure on 5PC_Unit1
(i.e. configure both stack members)

Connect the following cables up:

5PC_Unit1 port 1  to 6PC_Unit1 port 1

5PC_Unit1 port 2 to 6PC_Unit2 port 1

5PC_Unit2 port 1  to 6PC_Unit1 port 2

5PC_Unit2 port 2 to 6PC_Unit2 port  2

Effectively creating 4 links between 4
switches and 2 separate stacks. Would this be the correct procedure to follow?

Also, I’ve noticed a number of guides mention
setting the spanning tree mode of the port channel to portfast – however I’ve
also read this shouldn’t be used on inter switch links and SPT sees aggregate
links as a single link.

Please advise if this procedure is correct.

Thanks

 

 

Anonymous

5 Practitioner

 • 

274.2K Posts

September 4th, 2013 06:00

On that old of a firmware enabling portfast globally may mean that portfast is set to auto and if the port sees a bpdu it turns off portfast. Or it may just be implemented inconsistent. Either way, on this firmware setting portfast manually may be the best way to go. I would not keep portfast enabled globally and hope it does what you want it to.

 

If you do want to use auto-portfast, I suggest updating firmware.

http://www.dell.com/support/drivers/us/en/555/DriverDetails/Product/powerconnect-6224?driverId=9W9KX&osCode=NAA&fileId=3214219303&languageCode=en&categoryId=NI

Anonymous

5 Practitioner

 • 

274.2K Posts

August 20th, 2013 11:00

Sounds like you are the right path with the configuration. Here are a couple suggestions.

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.

console(config-if)# switchport mode general

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

console(config-if)# switchport general pvid 1

• Portfast Allows immediate transition to a forwarding state

• Port still participates in STP

• Used for non-switch devices

• Clients

• Servers

• Printers

• Prevents unnecessary timeouts from DHCP servers

• Portfast configuration ignored when port is connected to another switch

aetius80

1 Rookie

 • 

34 Posts

August 23rd, 2013 06:00

Thanks for the information. Just to confirm, do I definitely need to use "general" mode on both the 6224 and 8024? The reason why I ask is because I spoke to a Dell technician on the phone and he said to use trunk and I wouldn't be allowed to use general - however from I read, I believe the correct option is to use general, then add the vlans and use the pvid as you mention above.

I could do with some general advice on re-cabling switches whilst keeping down time to a minimum. What I'm thinking of doing is:

1. Creating port channels
2. Ensure all edge ports are set to portfast (if my understanding is right I can set this at a global level on the 6224 and 8024, with the configuration        being ignored by ports which are being used for inter switch links)
3. Plug my cables in for the new uplinks (matching the port channel config)

At step 3 I'm hoping that rapid spanning tree kicks in and I'll have minimal down time on the ports. My aim is to ensure that down time is 0, but failing that keep it to a minimum.

 Is it possible to have 0 down time when re-cabling switches? 

Thanks

 

Anonymous

5 Practitioner

 • 

274.2K Posts

August 23rd, 2013 11:00

You are not required to use General mode, you can use Trunk mode. Just on the 62xx switch in order to allow management traffic we need to use General mode on the 62xx. If you don’t need management traffic, then use the Trunk mode.

 

I think the easiest way to implement portfast with the least amount of administration would be to

use the spanning-tree auto-portfast command to set the port to auto portfast

mode. This enables the port to become a portfast port if it does not see any

BPDUs for 3 seconds. Use the “no” form of this command to disable auto

portfast mode.

 

This example is only on one port, but you could do it for the full range of ports.

console#config

console(config)#interface ethernet 4/g1

console(config-if-4/g1)#spanning-tree auto-portfast

 

When it comes to 0 downtime, it will really depend on current network topology and projected topology. I would suggest spending some time to map out what ports are currently blocking and path costs, so that when you make the new connection you know what the outcome is. Would hate to just expect STP to take care of things, but instead it ends up blocking the new connection.

 

If you can show us a basic diagram of how your network is setup, and where this new connection will be in the network, we can help look things over.

aetius80

1 Rookie

 • 

34 Posts

September 2nd, 2013 08:00

Thanks Daniel,

I've attached a network diagram below. I don't think I can use auto portfast on the 6224 switch as it's currently running firmware 2.2.0.3 and that doesn't have an auto port fast setting, but does have port fast.

I've had a look and STP port fast is enabled switch wide, but if I check the status of individual ports in the switch web browser GUI looking at "All ports" STP settings, some ports show up as being enabled for "fast link" and others not - does this mean STP port fast is applied in an incosistent manner, despite being set globally?

I've decided to only enable port fast on the ports I need so am using the approach below:

  1. LANSTACK1&2(config)# interface range ethernet 1/g1, 1/g36               (only configure portfast on edge ports)
  2. LANSTACK1&2(config)# spanning-tree portfast
  3. LANSTACK1&2(config)# interface range ethernet 1/g40, 2/g36
  4. LANSTACK1&2(config)# spanning-tree portfast
  5. LANSTACK1&2(config)# interface range ethernet 2/g40, 2/g48
  6. LANSTACK1&2(config)# spanning-tree portfast
  7. LANSTACK1&2(config)# Interface 1/g37, 1/g38, 2/g37, 2/g38            (select ports1 & 2 on both stack members)
  8. LANSTACK1&2 (config-if)# channel-group 1 mode active     (enable ports with LACP, dynamic)
  9. LANSTACK1&2# Show interfaces port-channel 1 (confirm interfaces are in the port channel)
  10. LANSTACK1&2 (config)Interface port-channel 1
  11. LANSTACK1&2 (config-if)# Switchport mode general
  12. LANSTACK1&2 (config-if)# Switchport general pvid 1
  13. LANSTACK1&2 (config-if)# Switchport general allowed vlan add 1, 10, 20, 30 tagged     
  14. LANSTACK1&2 (config-if)# exit
  15. LANSTACK1&2 (config)# exit

LANSTACK3&4 (config)# interface range te1/0/1,te2/0/20
LANSTACK3&4
(config-f)# spanning-tree auto-portfast

Then run through steps 8 to 15 on LANSTACK3&4 using ports te1/0/23, te1/0/24, te2/1/23 & te2/1/24

Switch diagram below. If this can be simplified by simply enabling spanning tree port fast on all switch ports (including the ports used for interconnects, that would be my preference, as long as it doesn't cause any issues).

Diagram below.

Thanks

 

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