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Best way to migrate cross stack etherchannel mode "on" to "active"

Hey guys,

 

I've a cross stack etherchannel with mode on between two datacenters and now want to switch to LACP.
Can I just go into the physical interfaces and do a "no channel-group X mode on" -> "channel-group X mode active" or will I have to shut the ports down or completely remove the Port-Channel interface? Can't find any migration document around and don't have test equipment here. :(

 

Any ideas?

 

Thanks! :)

Michael Please rate all helpful posts
13 REPLIES
Hall of Fame Super Gold

Can I just go into the

Can I just go into the physical interfaces and do a "no channel-group X mode on" -> "channel-group X mode active" or will I have to shut the ports down or completely remove the Port-Channel interface? 

Doing this will cause your etherchannel to go down and any traffic traversing the etherchannel will go nuts.  

 

Just enter "channel-group <NUMBER> mode active" will be less disruptive.

VIP Super Bronze

Hi,Yes, you can change it

Hi,

Yes, you can change it from "on" to channel-group X mode active or passive without shutting down the portchannel interface. There will be short outage while configuring both sides of the portchannel. with the new config.

HTH

Hi,I changed it now to active

Hi,

I changed it now to active but they now are working in individual state :(

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
2      Po2(SD)         LACP      Gi1/0/1(I)  Gi2/0/3(I)

Same on the other side, but there's Port-Channel 1 (thought the LACP ID's can differ?).

 

Michael Please rate all helpful posts
Hall of Fame Super Gold

See the "(I)"?  This means

See the "(I)"?  This means "Initializing".  

 

Post the "sh logs".  The logs can provide valuable clues as to why the links are down.  Port-channel numbers are locally insignificant.  

Hi Leo,description tells me

Hi Leo,

description tells me that I stands for "stand-alone"

 

lags:  D - down        P - bundled in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      f - failed to allocate aggregator

        M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port


Number of channel-groups in use: 4
Number of aggregators:           4

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
2      Po2(SD)         LACP      Gi1/0/1(I)  Gi2/0/3(I)

 

I turned on "deb lacp" and "deb lacp events" but I only get:

May 14 04:41:18 MET-1DS: LACP: lacp_insert_partner_cd_inhibitor: didn't change sync flag.
May 14 04:41:18 MET-1DS: LACP: lacp_send_lacpdu: (Gi1/0/1) About to send the 110 LACPDU
May 14 04:41:18 MET-1DS: LACP: lacp_write: LACP 124 bytes out Gi1/0/1
May 14 04:41:45 MET-1DS: LACP: lacp_insert_partner_cd_inhibitor: didn't change sync flag.
May 14 04:41:45 MET-1DS: LACP: lacp_send_lacpdu: (Gi1/0/1) About to send the 110 LACPDU
May 14 04:41:45 MET-1DS: LACP: lacp_write: LACP 124 bytes out Gi1/0/1
May 14 04:42:12 MET-1DS: LACP: lacp_insert_partner_cd_inhibitor: didn't change sync flag.
May 14 04:42:12 MET-1DS: LACP: lacp_send_lacpdu: (Gi1/0/1) About to send the 110 LACPDU
May 14 04:42:12 MET-1DS: LACP: lacp_write: LACP 124 bytes out Gi1/0/1

In the cisco docs I read that when a port comes to mode active and the other side is mode on, it will not join the lacp group. In fact when I change from on to active this would happen or not? Don't know how to debug it.

 

Thanks

Michael

 

Michael Please rate all helpful posts
Hall of Fame Super Gold

Could you please provide the

Could you please provide the interface configuration for the two physical interfaces and the etherchannel interface?

 

Post the configurations for both switches.

Sure, Switch-A:Switch Ports

Sure, Switch-A:

Switch Ports Model              SW Version            SW Image
------ ----- -----              ----------            ----------
*    1 30    WS-C3750X-24       12.2(55)SE1           C3750E-UNIVERSALK9-M
     2 30    WS-C3750X-24       12.2(55)SE1           C3750E-UNIVERSALK9-M

interface GigabitEthernet1/0/1
 description X
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 18,60,64-66,68,100-102,104,105,200,251,900,902
 switchport trunk allowed vlan add 903,906,911,934,937,939
 switchport mode trunk
 channel-group 2 mode active
end

interface GigabitEthernet2/0/3
 description X
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 18,60,64-66,68,100-102,104,105,200,251,900,902
 switchport trunk allowed vlan add 903,906,911,934,937,939
 switchport mode trunk
 channel-group 2 mode active
end

interface Port-channel2
 description X
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 18,60,64-66,68,100-102,104,105,200,251,900,902
 switchport trunk allowed vlan add 903,906,911,934,937,939
 switchport mode trunk
end

 

 

Switch-B:

*    1 30    WS-C3750X-24       15.0(1)SE2            C3750E-UNIVERSALK9-M
     2 30    WS-C3750X-24       15.0(1)SE2            C3750E-UNIVERSALK9-M

interface GigabitEthernet1/0/1
 description Y
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 18,60,64-66,68,100-102,104,105,200,251,900,902
 switchport trunk allowed vlan add 903,906,911,934,937,939
 switchport mode trunk
 channel-group 1 mode active
end

interface GigabitEthernet2/0/1
 description Y
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 18,60,64-66,68,100-102,104,105,200,251,900,902
 switchport trunk allowed vlan add 903,906,911,934,937,939
 switchport mode trunk
 channel-group 1 mode active
end

interface Port-channel1
 description Y
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 18,60,64-66,68,100-102,104,105,200,251,900,902
 switchport trunk allowed vlan add 903,906,911,934,937,939
 switchport mode trunk
end

 

Michael Please rate all helpful posts
Hall of Fame Super Gold

Everything looks OK.  Hmmmm .

Everything looks OK.  Hmmmm ... I got a strange feeling I've seen this issue before.  

 

On both ends, remove the etherchannel config.  SO what you do is this:

config t
 no interface Po <NUMBER>
 interface range <PORT> , <PORT>
 no channel-group <NUMBER> mode active 
 channel-group <NUMBER> mode active

Strange, isn't it? Was to

Strange, isn't it? Was to lazy to read all the caveats for the different releases :)

Next maintenance window is on tuesday, will try to reset it with the no statements.

 

Thanks

Michael Please rate all helpful posts
Hall of Fame Super Gold

Strange because I only see

Strange because I only see this happening on old IOS for 6500.  Never seen a behaviour like this on a 3750.

Sorry for coming back so

Sorry for coming back so lately, today was next maintenance window.

 

I dialed via ISDN to console servers and did on both ends:

conf t
int port-ch X
shut
exit
no int port-ch X

(phys. If was shut and no channel config)

Then go into phys If and did a channel-group X mode active, back to port-ch X and added the trunking stuff.

Last a no shut and the ... same thing! Inactive state just STP blocking the vlans. 

This must be a IOS bug, I'll now walk trough the changelog.

Michael Please rate all helpful posts
Cisco Employee

Hi everyone,@ciscomax: This

Hi everyone,

@ciscomax: This is a blind shot but can you try to add the VLAN 1 into the list of allowed VLANs on all physical ports that you want to bundle into an EtherChannel on both switches? There is a very remote possibility that because of some IOS issue, LACPDUs (which are sent in the native VLAN and that seems to be VLAN 1 in your config) cannot be sent or received on trunks with the VLAN 1 pruned. This shouldn't happen in normal case but obviously, we're not dealing with normal behavior here.

Best regards,
Peter

 

I checked every changelog for

I checked every changelog for LACP or etherchannel, nothing found.
Your shot sounds good, I'll give it a try next maintenance window.

 

Thanks!

Michael Please rate all helpful posts
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