Load Balancing Methods for Port Channels on Nexus

[PNW Weer]

There are two nexus 7K switches in each datacentre connected via OTV.  L2 port- channel is configured (consist with two 10G ports) between two DCs to support the OTV connectivity.

Port-channel load balance uses following mechanisms, but I can't see its load balancing between two 10g ports. Always utilises one physical interface and no usage on other link. I believe all the packets between two DCs consist with same source and destination IP/MAC details, according to the OTV implementation.

src -dst -IP

src-dst-mac

Therefore I am intending to change the  load balancing mechanism to  use  src-dst-port. Please let me know if anyone has implement this on production system and if any disruptions such as resetting port channels?

Thanks

[Brandon Rumer (Cisco)]

Your L2 Port-channel should be pointing back at your own DC's VDC, and then OTV encapsulates the appropriate traffic via your L3 join interface. Yes, this load-balancing follows typical LACP methods. So, I assume your problem is that you are not load-balancing down to your own DC connection (typically a different VDC on a 7k)?

With OTV, there is no port-channel between the different DCs. Therefore, Im not understanding your question.

You may want to check out 'otv depolarization.'
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/nx-os/OTV/config_guide/b_Cisco_Nexus_7000_Series_NX-OS_OTV_Configuration_Guide/adv-otv.html#concept_4A141E90550244C5A0F026C5881C69B2

Additionally, if you have multiple AEDs in the same OTV site, then you will automatically load-balance based on even-odd VLAN numbers. That info is somewhere in the above link.

Hope this helps,

Brandon

[PNW Weer]

Hi Brandon

There are two port-channels, details as follows.

L3 PO  (Same DC)- connects OTV VDC and Routed VDC - currently not load balancing.

L2 PO (between DCs) - connected routed VDCs between datacenters, I know this is confusing. This PO is only allowed a single VLAN to support OSPF. SVI configured on each routed VDC acts as the router ID - PO is  not load balancing.

Next question you will ask if you already have L2 between DCs, why you want OTV. We have configured multiple overlays to segregate corporate, DMZ and internet traffic.

Thanks

[Brandon Rumer (Cisco)]

Thanks for clarifying.

Are you using LACP? The physical interfaces should be 'channel-group [10] mode active' on both sides.

What are the slot/port numbers for one of your POs?

[PNW Weer]

Hi Brumer

Configurations as follows,

interface Ethernet3/31
  description Link between  VDC's
  switchport
  switchport mode trunk
  switchport trunk allowed vlan 906
  mtu 9216
  channel-group 100 mode active
  no shutdown

interface Ethernet3/32
  description Link between  VDC's
  switchport
  switchport mode trunk
  switchport trunk allowed vlan 906
  mtu 9216
  channel-group 100 mode active
  no shutdown

100   Po100(SU)   Eth      LACP      Eth3/31(P)   Eth3/32(P)

--------

Port Channel Load-Balancing Configuration for all modules:
Module 3:
  Non-IP: src-dst mac
  IP: src-dst ip rotate 0
Module 6:
  Non-IP: src-dst mac
  IP: src-dst ip rotate 0
Module 8:
  Non-IP: src-dst mac
  IP: src-dst ip rotate 0
Module 9:
  Non-IP: src-dst mac
  IP: src-dst ip rotate 0

Thanks