[j-nsp] load balancing 'per flow'

[Saku Ytti]

On (2004-07-30 15:49 +0530), Bosco Sachanandani wrote:
 
> I understand that Internet Processor II only supports load balancing per flow and not per packet (as CEF does).

 If I remember correctly even per packet is available by forwarding-table
export policy, I wouldn't want to use it myself though so not sure
how it's configured exactly. 

> Can someone throw some more light on what exactly does 'per flow' mean ? The reason I am asking this is:

Depends on your hash-key:
foo at bar# set forwarding-options hash-key family inet ?
Possible completions:
+ apply-groups         Groups from which to inherit configuration data
+ apply-groups-except  Don't inherit configuration data from these groups
> layer-3              Include Layer 3 (IP) data in the hash key
> layer-4              Include Layer 4 (TCP or UDP) data in the hash key

> 1) Is it per VRF ? For eg all PE to PE traffic for VRF A will go via link 1 and all PE to PE traffic for VRF B will go via link 2?

 No, it's per flow. But as it's VRF, surely you can route VRF A via link1
and VRF via link2 if you want, no special magic needed there or am I
missing something there? 

> 2) Or is it that 'flows' between various IP addresses WITHIN each VRF will go via alternate links ? For eg. Prefix 10.0.0.0/8 which is within VRF A will go via Link 1 and Prefix 20.0.0.0/8 which is also within VRF A will go via Link 2 ?

 ~Yes. They would get different hash-key in both layuer-3 and layer-4
setup and qualify to be put in different link if routing allows it. 
 With layer-4 hash key, even packets between same addresses but different
ports would qualify to be put in different links.

> For any sort of load balancing between the 2 PE to PE links, do I need to explicitly add a policy  or will it happen anyway if the IGP recognises it as equal cost links ? We are using LDP between these routers.

 I think it will happen automaticly, if there is equal cost link and if
hash key allows it.

-- 
  ++ytti