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I have two Dell PowerConnect 5424 switches, with current firmware installed. I'm trying to configure a LAG group, which will link the two switches for a certain number of ports (8-16) on each switch. But not having much success.

No matter what I try, I'm unable to ping a host on switch 2, from a host on switch 1. I've included the relevant bits of my config below.

Any assistance would be greatly appreciated.

In case of relevance, ports 1-7 are already in use for a different SAN (and EMC) which has separate subnets for each switch, so no LAG required. I have those ports tagged as 'switchport access vlan 2'

  • I need ports (8-16) on each switch to be linked with a LAG (LAG 3).
  • The hosts on these ports are in the same subnet

  • The hosts will be transmitting untagged traffic (Equallogic array hosts/arrays)

  • Four ports (20-23) on each switch are in the LAG group

  • Each of these four ports are connected to the corresponding ports on other switch

  • The should forward traffic from ports 8-16 to equivalent on other switch.

  • I've tried various permutations of general/trunk/access modes

Partial config

spanning-tree mode rstp

interface range ethernet g(8-16)
    spanning-tree portfast
    flowcontrol on
    switchport access vlan 3
exit

interface range ethernet g(20-23)
    channel-group 3 mode on
exit

interface port-channel 3
    switchport mode trunk
    switchport trunk allowed vlan add 3
exit

vlan database
    vlan 2, 3
exit

interface vlan 3
    name eql
exit

Edit: Results of some commands

console# show interfaces port-channel 3           

Load balancing: Layer 2.

Gathering information...
Channel  Ports
-------  -----
ch3      Active: g(20-23)

console# show interfaces switchport port-channel 3
Port : ch3
Port Mode: Trunk
Gvrp Status: disabled
Ingress Filtering: true
Acceptable Frame Type: admitAll
Ingress UnTagged VLAN ( NATIVE ): 1
Protected: Disabled

Port is member in: 

Vlan               Name               Egress rule Port Membership Type 
---- -------------------------------- ----------- -------------------- 
 1                  1                  Untagged          System        
 3                 eql                  Tagged           Static        


Forbidden VLANS: 
Vlan               Name               
---- -------------------------------- 


Classification rules: 

Protocol based VLANs: 
Group ID Vlan ID 
-------- ------- 

console# show interfaces switchport ethernet g8
Port : g8
Port Mode: Access 
Gvrp Status: disabled
Ingress Filtering: true
Acceptable Frame Type: admitAll
Ingress UnTagged VLAN ( NATIVE ): 3
Protected: Disabled

Port is member in: 

Vlan               Name               Egress rule Port Membership Type 
---- -------------------------------- ----------- -------------------- 
 3                 eql                 Untagged          Static        


Forbidden VLANS: 
Vlan               Name               
---- -------------------------------- 


Classification rules: 

Protocol based VLANs:                       
Group ID Vlan ID 
-------- ------- 

console# show arp

ARP timeout: 3600 Seconds

  VLAN    Interface     IP address        HW address          status      
--------------------- --------------- ------------------- --------------- 
vlan 1     g24        10.12.0.2       00:13:60:f6:36:b9   dynamic         
vlan 1     g24        10.12.1.142     00:1c:23:3d:72:5b   dynamic         
vlan 1     g24        10.12.1.201     10:9a:dd:57:46:72   dynamic   

console# show vlan 

Vlan       Name                   Ports                Type     Authorization 
---- ----------------- --------------------------- ------------ ------------- 
 1           1             g(17-19,24),ch(1-8)        other       Required    
 2          ax4                  g(1-7)             permanent     Required    
 3          eql                g(8-16),ch3          permanent     Required 

Switch 1
console# show bridge address-table vlan 3
Aging time is 300 sec

  Vlan        Mac Address       Port     Type    
-------- --------------------- ------ ---------- 
   3       00:09:8a:0a:15:45    g11    dynamic   
   3       00:15:17:6b:2b:cf    g10    dynamic   
   3       00:50:56:7f:ee:ef    g12    dynamic  

Switch 2
console# show bridge address-table vlan 3
Aging time is 300 sec

  Vlan        Mac Address       Port     Type    
-------- --------------------- ------ ---------- 
   3       00:09:8a:0a:15:44    g11    dynamic

Spanning Tree details after I disabled it!! I presume the 1.2million BPDU packets are what caused my problems! 

show spanning-tree detail (excerpt from)
...
Port g24 enabled
State: forwarding                              Role: root
Port id:  128.24                                Port cost: 4
Type: P2P    (configured:Auto  ) STP           Port Fast: No (configured:No)
Designated bridge Priority : 32768             Address: 00:1e:4f:01:3a:77
Designated port id: 128.43                       Designated path cost: 4
Guard root: Disabled                           BPDU guard: Disabled
Number of transitions to forwarding state: 1
BPDU: sent 25, received 1205133

Port ch3 enabled
State: disabled                                Role: disabled
Port id:  128.49                                Port cost: 4
Type: N/A (configured:Auto   RSTP)             Port Fast: No (configured:No)
Designated bridge Priority : 32768             Address: 00:1e:c9:90:05:12
Designated port id: 128.49                       Designated path cost: 8
Guard root: Disabled                           BPDU guard: Disabled
Number of transitions to forwarding state: 1
BPDU: sent 415, received 2

** More Spanning Tree details **

SWITCH 1
console# show spanning-tree active


Spanning tree enabled mode RSTP
Default port cost method:  short



  Root ID    Priority    32768
             Address     00:14:22:6e:92:41
             Cost        8
             Port        g24
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
  Bridge ID  Priority    32768
             Address     00:1e:c9:90:05:12
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

  Number of topology changes 180 last change occurred 00:01:01 ago
  Times:  hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15

Interfaces
 Name   State   Prio.Nbr   Cost     Sts   Role PortFast       Type        
------ -------- -------- --------- ------ ---- -------- ----------------- 
  g1   enabled   128.1       4      Frw   Desg    No       P2P (RSTP)     
  g2   enabled   128.2       4      Frw   Desg    No       P2P (RSTP)     
  g3   enabled   128.3       4      Frw   Desg    No       P2P (RSTP)     
  g4   enabled   128.4       4      Frw   Desg    No       P2P (RSTP)     
  g5   enabled   128.5       4      Frw   Desg    No       P2P (RSTP)     
  g6   enabled   128.6       4      Frw   Desg    No       P2P (RSTP)     
  g7   enabled   128.7       4      Frw   Desg    No       P2P (RSTP)     
 g10   enabled   128.10      4      Frw   Desg   Yes       P2P (RSTP)     
 g11   enabled   128.11      4      Frw   Desg   Yes       P2P (RSTP)     
 g12   enabled   128.12      4      Frw   Desg   Yes       P2P (RSTP)     
 g24   enabled   128.24      4      Frw   Root    No        P2P (STP)     
 ch3   enabled   128.49      4      Frw   Desg    No       P2P (RSTP)

SWITCH 2
console# show spanning-tree active


Spanning tree enabled mode RSTP
Default port cost method:  short



  Root ID    Priority    32768
             Address     00:14:22:6e:92:41
             Cost        8
             Port        g24
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
  Bridge ID  Priority    32768
             Address     00:1e:c9:90:06:1a
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

  Number of topology changes 179 last change occurred 01:06:29 ago
  Times:  hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15

Interfaces
 Name   State   Prio.Nbr   Cost     Sts   Role PortFast       Type        
------ -------- -------- --------- ------ ---- -------- ----------------- 
  g1   enabled   128.1       4      Frw   Desg    No       P2P (RSTP)     
  g2   enabled   128.2       4      Frw   Desg    No       P2P (RSTP)     
  g3   enabled   128.3       4      Frw   Desg    No       P2P (RSTP)     
  g4   enabled   128.4       4      Frw   Desg    No       P2P (RSTP)     
  g5   enabled   128.5       4      Frw   Desg    No       P2P (RSTP)     
  g6   enabled   128.6       4      Frw   Desg    No       P2P (RSTP)     
  g7   enabled   128.7       4      Frw   Desg    No       P2P (RSTP)     
 g11   enabled   128.11      4      Frw   Desg   Yes       P2P (RSTP)     
 g12   enabled   128.12      4      Frw   Desg   Yes       P2P (RSTP)     
 g24   enabled   128.24      4      Frw   Root    No        P2P (STP)     
 ch3   enabled   128.49      4      Dscr  Altn    No       P2P (RSTP) 

console# show spanning-tree blocked


Spanning tree enabled mode RSTP
Default port cost method:  short



  Root ID    Priority    32768
             Address     00:14:22:6e:92:41
             Cost        8
             Port        g24
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
  Bridge ID  Priority    32768
             Address     00:1e:c9:90:06:1a
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

  Number of topology changes 179 last change occurred 01:06:51 ago
  Times:  hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15

Interfaces
 Name   State   Prio.Nbr   Cost     Sts   Role PortFast       Type        
------ -------- -------- --------- ------ ---- -------- ----------------- 
 ch3   enabled   128.49      4      Dscr  Altn    No       P2P (RSTP)
link|improve this question
have you tried channel-group 3 mode auto on both sides? – Mike Pennington May 11 '11 at 9:22
Thanks - Yes, I tried that ready - made no difference from what I can see - g20-23 went offline, then online again during the changes. – barryj May 11 '11 at 9:59
Have you checked mac-learning on both sides for anomalies? – Mike Pennington May 11 '11 at 10:04
@Mike - can you elaborate on that? – barryj May 11 '11 at 10:18
barryj, are mac-addresses learned correctly on the switch it is connected to... then on the switch across the LAG. You should see the source mac learned across the LAG for both devices if packets are going both ways. If this is not happening, you get a clue for where things have broken – Mike Pennington May 11 '11 at 10:20
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2 Answers

up vote 1 down vote accepted

You certainly don't show any mac-learning across either side of the LAG, which indicates to me that there is something more basic wrong.

  1. Start by ensuring that your ethernet interfaces participating in the LAG are up on both sides
  2. Ensure that you have the same LAG configuration on both sides (easiest is usually auto). Then ensure that LACP has brought the LAG virtual interface up
  3. Ensure your vlan trunking parameters are the same on both sides
  4. Ensure that spanning-tree is not blocking the LAG due to another redundant link between the switches. If there is a redundant link, shut that down too.

Failing that, remove the LAG configuration from both sides and shutdown all but one ethernet link between the switches. Try to get connectivity working like that. Once you have this working, add the LAG configuration and duplicate the config that worked on the single ethernet link into the LAG ports.

link|improve this answer
@Mike - 1) Interfaces are up. 2) I changed mode to auto ealier today - 3) Just diffed the running-config on both switches - only difference is IP of managment port and Dell Tag number. Regarding 4) I'll have to reread that - I've only 4 links between the switches (the four LAG members). I'll try removing the LAG when I get back to the office, and just link two ports - should I just pop a cable between two ports in the g(8-16) range? – barryj May 11 '11 at 12:55
@barryj, if you use a port in g(8-16), you will have the link in access mode... that is fine for test purposes, but I assume you needed to trunk more than vlan3 across that link... which means trunk mode. If you need trunk mode, then I would use a port in g(20-23). – Mike Pennington May 11 '11 at 13:17
@Mike - OK I removed the LAG and then recreated the LAG with a single link member. Still same issue. I then tried the following command: 'spanning-tree disable' under the port-channel config. I ran this on both switches and I was able to ping the IP. However, I think it nearly killed the rest of my network - so I quickly reversed it. Suddenly had four people beside me lose network services. Port 24 on each switch is connected to my regular network, and is part of the default VLAN 1. I'm not really sure what I just did. – barryj May 11 '11 at 14:17
1  
@barryj, my assumption (perhaps a bad one) is that you were doing this in a maintenance window. If these devices are not isolated from the rest of the network, you should be waiting for a designated maintenance time so the impact of your changes are expected and (hopefully) minimized. It sounds like you have some spanning-tree dynamics happening. You need to know where the spanning-tree root should be; If your LAGs are getting blocked by spanning-tree (see show spanning-tree active, show spanning-tree blocked), see if you can add them to a pre-existing LAG (in a maintenance window) – Mike Pennington May 11 '11 at 14:44
1  
@barryj, your comment about a management port makes a lot of sense. It may be possible to put your management vlan on the LAG and remove the separate mgt port, however, this requires understanding the big-picture topology. Someone (hopefully) has a topology map that can clarify this. One thing is important though... be sure that all switch-to-switch connections have STP, MSTP, or RSTP enabled. All spanning-tree protocols in a single ethernet broadcast domain should be the same type (either STP, RSTP, or MSTP). – Mike Pennington May 11 '11 at 14:58
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up vote 0 down vote

Can you post the output of the command below please:

show interfaces port-channel 3

Also, if the LAG group is only going to carry traffic for VLAN3 then you shouldn't need to form a trunk between the two switches, setting VLAN3 as the access VLAN for the port-channel should adequate.

link|improve this answer
will add results to question post – barryj May 11 '11 at 10:10
For future options it might be better to make the inter-switch link a trunk and prune the existing VLANs. In the future if you ever did need to add a VLAN, you could just allow it, instead of having to reconfigure your ports. – Robert May 11 '11 at 15:24
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