Etherchannel load-balancing on per-VLAN basis

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Jun 3rd, 2010
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Greetings!


The case:


Two switches (WS-C3560E-12D-S) that are connected through etherchannel (three TenGig interfaces). Port-channels on both switches are in trunking mode. Etherchannel load-balancing configuration for now is: src-dst-ip (source XOR destination IP address).


I want to have a more conveinient way to load-balance traffic between vlan members on both switches in case of failure of one of port-channel member links.


I read "VLAN Mapping to Gigabit EtherChannel (GEC) Member Links" http://www.cisco.com/en/US/docs/ios/lanswitch/configuration/guide/lsw_cfg_gecvlan.html

but still cannot guess is it for my case.


I mean, I would like to manually configure an active and failover port-channel member interfaces for each vlan in the port-channel trunk.


Any ideas or technologies that would fit my case?


Thanks, Alex


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Giuseppe Larosa Thu, 06/03/2010 - 07:24
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Hello Alex,

LACP allows for this by using LACP priority on member links


by using a config like the following:



h run int te1/3

Building configuration...


Current configuration : 227 bytes

!

interface TenGigabitEthernet1/3

switchport

switchport trunk encapsulation dot1q

switchport mode trunk

mtu 9216

logging event link-status

>>>>lacp port-priority 65535

channel-protocol lacp

channel-group 1 mode active

end


without placing the command on the other two member links this port is kept in halted mode



sh etherchannel 1 det

Group state = L2

Ports: 3   Maxports = 16

Port-channels: 1 Max Port-channels = 16

Protocol:   LACP

Minimum Links: 0

                Ports in the group:

                -------------------

Port: Te1/1

------------


Port state    = Up Mstr In-Bndl

Channel group = 1           Mode = Active      Gcchange = -

Port-channel  = Po1         GC   =   -         Pseudo port-channel = Po1

Port index    = 1           Load = 0x55        Protocol =   LACP


Flags:  S - Device is sending Slow LACPDUs   F - Device is sending fast LACPDUs.

        A - Device is in active mode.        P - Device is in passive mode.


Local information:

                            LACP port     Admin     Oper    Port        Port

Port      Flags   State     Priority      Key       Key     Number      State

Te1/1     SA      bndl      32768         0x1       0x1     0x1D        0x3D 


Partner's information:


          Partner Partner   LACP Partner  Partner   Partner  Partner     Partner

Port      Flags   State     Port Priority Admin Key Oper Key Port Number Port State

Te1/1     SA      bndl      32768         0x0       0x1      0x1D        0x3D 


Age of the port in the current state: 22d:13h:12m:43s


Port: Te1/3

------------


Port state    = Up Mstr Hot-stdby Not-in-Bndl

Channel group = 1           Mode = Active      Gcchange = -

Port-channel  = null        GC   =   -         Pseudo port-channel = Po1

Port index    = 0           Load = 0x00        Protocol =   LACP


Flags:  S - Device is sending Slow LACPDUs   F - Device is sending fast LACPDUs.

        A - Device is in active mode.        P - Device is in passive mode.


Local information:

                            LACP port     Admin     Oper    Port        Port

Port      Flags   State     Priority      Key       Key     Number      State

Te1/3     FA      hot-sby   65535         0x1       0x1     0x1F        0x7  


Partner's information:


          Partner Partner   LACP Partner  Partner   Partner  Partner     Partner

Port      Flags   State     Port Priority Admin Key Oper Key Port Number Port State

Te1/3     FA      hot-sby   65535         0x0       0x1      0x1F        0x7  


Age of the port in the current state: 22d:13h:53m:12s


Port: Te1/5

------------


Port state    = Up Mstr In-Bndl

Channel group = 1           Mode = Active      Gcchange = -

Port-channel  = Po1         GC   =   -         Pseudo port-channel = Po1

Port index    = 0           Load = 0xAA        Protocol =   LACP


Flags:  S - Device is sending Slow LACPDUs   F - Device is sending fast LACPDUs.

        A - Device is in active mode.        P - Device is in passive mode.


Local information:

                            LACP port     Admin     Oper    Port        Port

Port      Flags   State     Priority      Key       Key     Number      State

Te1/5     SA      bndl      32768         0x1       0x1     0x1E        0x3D 


Partner's information:


          Partner Partner   LACP Partner  Partner   Partner  Partner     Partner

Port      Flags   State     Port Priority Admin Key Oper Key Port Number Port State

Te1/5     SA      bndl      32768         0x0       0x1      0x1E        0x3D 


Age of the port in the current state: 23d:12h:48m:12s


                Port-channels in the group:

                ----------------------


Port-channel: Po1    (Primary Aggregator)


------------


Age of the Port-channel   = 793d:01h:59m:40s

Logical slot/port   = 14/2          Number of ports = 2


Hope to help

Giuseppe



Alexander Demin Fri, 06/04/2010 - 00:28
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Here is the desired functional scheme. We talk about L2 etherchannel, while VLAN mapping for Etherchannel (http://www.cisco.com/en/US/docs/ios/lanswitch/configuration/guide/lsw_cfg_gecvlan.html) is for L3.


Again: I want functionality for manual, static assignment of port-channel member links (active and standby(failover)) to each VLAN that need transport through the port-channel trunk. It seems to be technically quite possible, as frames that travel in trunk are tagged.


From the case it is evident, that static assignment of 3d TenGig interface as failover for VLAN2 is more preferable than to assign 2d TenGig interface, cause summary of used bandwidth will be less.


LACP does not seem to perform load-balance in port-channel on per-VLAN basis.


Hope the is some decision.


Anyway, thanks for your attention!


Alex. 

Giuseppe Larosa Fri, 06/04/2010 - 01:01
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Hello Alex,

the feature of the link is supported on ASR I suppose.


As far as I know it is not supported on C6500 or other multilayer switches


However, with default settings you get load balancing on IP SA exor IP DA and this could help you


Hope to help

Giuseppe

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