Nexus 5600 symmetric port-channel load balancing

[Mate Grbavac]

Hi,

I have 4 policy servers between two Nexus 5600 switches. Server are fully L2 transparent and each server has two interfaces.

From perspective of Nexuses each server act as a wire so from L2 perspective Nexuses are directly connected. Port E1/1 on N5k-1 <----> E1/1 on N5k-2; E1/2 <----> E1/2; E1/3 <---->E1/3; e1/4 <----> E1/4

This four connections (servers) are on each Nexus configured as port-channel.

To ensure correct functioning of policy platform on servers, I need to ensure that traffic for each session (source-destination IP pair)  is going through same server in both directions.

Is there any predictible load-balancing algorithm that will hash in same way on both Nexus switches. For example, traffic between 192.168.1.100 and 100.100.100.100 will go through port eth1/2 on both switches.

It not problem for me to recable for example port 4 to port 2 on one of the switches if for specific IP src/dst pair of IP addresses one switch will always select port 4 and second port 2.

Here is diagram od system.

[InayathUlla Sharieff]

I personally dont believe that we can achieve this. This means that we need to tweak the hashing algorithm in such a way that always it has to use the following link while considering the parameters and performing the hashing. Sorry I doubt that we can achieve that irrespective of chainging the sr/dst load balancing method.

Something somewere I have read this not sure how much worth it is for you:-

Cisco has a new solution called ITD:

http://blogs.cisco.com/datacenter/itd-load-balancing-traffic-steering-clustering-using-nexus-5k6k7k

ITD (Intelligent Traffic Director) is a hardware based multi-Tbps Layer 4 load-balancing, traffic steering, redirection, and clustering solution on Nexus 5K/6K/7K series of switches. It supports IP-stickiness, resiliency, NAT (EFT), VIP, health monitoring, sophisticated failure handling policies, N+M redundancy, IPv4, IPv6, VRF, weighted load-balancing, bi-directional flow-coherency, and IPSLA probes including DNS. There is no service module or external appliance needed. ITD is much superior than legacy solutions like PBR, WCCP, ECMP, etc.

HTH

regards

Inayath

**Please rate if info is helpfull**

[Mate Grbavac]

Hi,

yes, I know for ITD and we are currently testing it for our solution. Something like:

http://blogs.cisco.com/wp-content/uploads/ITD-with-L2-ASA.pdf

But, there are also no any informations regarding symmetry of traffic.

What kind of solution then we should use for this purpose (symmertic baancing accros L2 transparent appliances)?

BR, Mate