Default Gateway for a system v/s Default gateway per Interface

[Ratan Gupta]

Hi Jonathan,

On 4/28/20 1:00 AM, Johnathan Mantey wrote:
> Ratan,
>
> Can you provide more info about how you plan to implement this?
I am not getting, Do you mean to say how to get the per interface 
gateway from system?  that would be through netlink, and during 
configuration we would use the systemd-networkd file configuration.
>
> The Redfish schemas already have a per IP addr Gateway entry, which 
> OBMC is ignoring. Is it better to modify the existing D-Bus schema 
> (i.e. versioning discussion), or just use what is presently in existence?
Redfish schema are getting changed to accommodate this through the 
following issue https://github.com/DMTF/Redfish/issues/3609.

The above issue(gateway/interface) exist only for the IPv4 redfish 
schema, IPv6 redfish is already having default gateway per interface

http://redfish.dmtf.org/schemas/v1/EthernetInterface.v1_5_1.json#/definitions/EthernetInterface

>
> That said, doing as you propose melds better with how IPMI (i.e Set 
> LAN Configuration Parameter 12) works.
>
> As Patrick pointed out, there's no IPMI or Redfish control over the 
> routing metric parameter. What are your thoughts on how to reconcile 
> applying a metric value?
We will go with default metric value as today as underlying stack tries 
for fallback gateway.
> I've long been desirous of getting Williams submission merged: 
> https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-networkd/+/20799
> as it can be used to improve the collection of netlink stats.
>
> Redfish exacerbates this whole problem by allowing a collection of 
> static IP addresses (and a DHCP addr) per NIC, unlike IPMI which was 
> very one to one with IP addr/NIC.
>
> Thanks for investigating this and working to implement a solution.
>
> On 4/27/20 4:11 AM, Ratan Gupta wrote:
>>
>> Thanks Patrick, William for sharing the feedbacks
>>
>> I will start working on the changes.
>>
>>
>> On 4/24/20 11:15 PM, William Kennington wrote:
>>> Sounds good to me, we have needed this for a long time because the 
>>> current gateway configuration breaks our v6 stack with multiple NICs.
>>>
>>> On Fri, Apr 24, 2020 at 8:21 AM Patrick Williams <patrick at stwcx.xyz 
>>> <mailto:patrick at stwcx.xyz>> wrote:
>>>
>>>     On Fri, Apr 24, 2020 at 08:36:26PM +0530, Ratan Gupta wrote:
>>>     > ~~~~~~~~~~~~~
>>>     > Kernel IP routing table
>>>     > Destination     Gateway         Genmask Flags   MSS Window  irtt
>>>     > Iface
>>>     > 0.0.0.0         19.168.2.1      0.0.0.0 UG        0 0          0
>>>     > eth0
>>>     > 0.0.0.0         10.10.10.1      0.0.0.0 UG        0 0          0
>>>     > eth1
>>>     > ~~~~~~~~~~~~~~
>>>     >
>>>     > Kernel will first try using the default gateway having higher
>>>     metric
>>>     > value and then fall back to the lower.
>>>
>>>     I'm not seeing us with an interface to adjust the metric for an
>>>     interface.  I think we need to add that at the same time?
>>>
>> Not now, As per my testing if metric value is not defined and both 
>> the routes
>>
>> having same metric then kernel tries one after other. We can bring 
>> the metric
>>
>> later.
>>
>>>       Otherwise, I
>>>     don't think we have a way to specify which interface
>>>     outside-the-subnet
>>>     should go (vs today we can set the default-gateway to the desired
>>>     interface's gateway).
>>>     -- 
>>>     Patrick Williams
>>>
>
> -- 
> Johnathan Mantey
> Senior Software Engineer
> *azad te**chnology partners*
> Contributing to Technology Innovation since 1992
> Phone: (503) 712-6764
> Email: johnathanx.mantey at intel.com <mailto:johnathanx.mantey at intel.com>

Ratan

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