LACP

[leyakhath muhammed]

Hi,

   If i  configure LACP on L3 switch (gig0/1 and gig0/2), and if these ports are connected to diffrent access switches (SW1 and SW2) ,Does  it  have any impact ?

       gig0/1(LACP) ----- gig0/1 trunk (L2 Access SW1)

L3{

       gig0/2(LACP)------ gig0/1 trunk (L2 Access SW2)

Thank you

[Flavio Miranda]

Hello Muhammad,

" definition, LAG is formed across two adjacent nodes which are directly connected to each other."

 The answer for your question would be certainly no.

 However. Some vendors have created some alternative.

MC-LAG, or Multi-Chassis Link Aggregation Group, is a type of LAG with constituent ports that terminate on separate chassis, thereby providing node-level redundancy.

[leyakhath muhammed]

can u explain in detail? should be no impact? right?

[Flavio Miranda]

Hello,

 Let me be more specific. Sometimes ago I did a test with two different FEX on the same chassis and did not work.

 Probably most of Cisco  switch we know will not work.

 By IEEE definition will not work.

[Julio E. Moisa · Accepted solution]

Hi,

Please correct me if I am understanding wrong, but based on this topology:

   gig0/1(LACP) ----- gig0/1 trunk (L2 Access SW1)

L3{

       gig0/2(LACP)------ gig0/1 trunk (L2 Access SW2)

You have something like that on the L3 switch

L3 SWITCH

int g0/1

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 1 mode active

int g0/2

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 1 mode active

int PO1

switchport trunk encapsulation dot1q

switchport mode trunk

no shutdown 

But you are going to connect the g0/1 to the L2 switch 1  and g0/2  to the L2 switch, if that is correct, you will not create a real etherchannel and it could generate a problem or it will not work as expected. Now if L2 switch 1 and 2 are stacked it will work properly if you set up LACP on that stack, because both switches will be seen like one switch.

 gig0/1(LACP) ----- gig0/1 trunk (L2 Access SW1)

L3{                                              | stacked switches

       gig0/2(LACP)------ gig0/1 trunk (L2 Access SW2)

Now if they are not stacked (different/separated L2 devices) you can create 2 different LACP interfaces: one for L2 switch 1 and other LACP interface for L2 Switch2, separately. 

L3 SWITCH

int g0/1

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 1 mode active

int g0/2

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 1 mode active

int PO1

description TO-L2-SWICH-1

switchport trunk encapsulation dot1q

switchport mode trunk

no shutdown 

int g0/3

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 2 mode active

int g0/4

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 2 mode active

int PO2

description TO-L2-SWICH-2

switchport trunk encapsulation dot1q

switchport mode trunk

no shutdown 

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