Port-channel questions?

[CiscoPurpleBelt]

Does port-channel load balance at all by default or do I actually have to configure it?

Also, let's say I have  a HA redundant set up, (2 access switches connecting to 2 core switches). Should I configure each access switch ports that connect to each core switch ports in the same port-channel number  (e.g. Po1 on access switch 1 and 2 ports going to Cores 1 and 2) and like wise on Cores?

[Seb Rupik · Accepted solution]

Hi there,

The default load balance shown with:

show port-channel load-balance

...configurable load balancing algorithms will vary between platforms. Check the configuration guides.

Regarding your second question, if I understand correctly. The port-channel ID number is arbitrary and can be different on each access switch, but for consistency should generally be the same. On the core switch which aggregates these port-channels then you should increment the port-channel ID number.

cheers,

Seb.

[CiscoPurpleBelt]

Awsome. Yes on core I have let's say Po1 which goes to Access switch 1, Po2 to access switch 2. ON all access switches I was thinking just keeping it Po1 for ports to core 1 and po 2 to ports for core 2.

[Joseph W. Doherty · Accepted solution]

You could do that, or you could number the access port-channel interfaces to match how they are numbered on the core. Additionally, you might number each port-channel, on both devices, to be globally unique, such as PO11, PO12, PO13 on core 1 to access switches 1, 2 and 3 and likewise PO21, PO22, PO23 for core 2 to access switches 1, 2 and 3. The latter approach, makes it clear what port-channel connects to what devices, regardless of which device you're referencing.

[CiscoPurpleBelt]

Awesome good advice. 

[Seb Rupik]

It is worth noting regarding implementing globlaly unique Po numbers, that some edge switching platforms have a very limited number. If I remember correclty on the 2960X the highest configurable number is 48.

cheers,

Seb.