Re: [vpp-dev] Some L2 Bridge API Questions

[Jon Loeliger]

John,

So, I see that, when creating a bridge domain using the API
call bridge_domain_add_del, one can specify some feature
flags of the domain as well as the mac-age parameter.

Later, it looks like one can alter the feature flags using the
API call bridge_flags, changing one or more features to be
enabled or disabled on the fly.

However, it looks like there is no mechanism to alter just
the mac-age parameter.

So, a few questions.  Is one expected to re-issue the bridge
domain "add" request again, with all the same flag-bits, but
with the new mac-age value?  Or is this just a missing API
call that is yet to be added?

In particular, I notice that the code in src/vnet/l2/l2_bd.c has a
command to set a new mac-age, but it doesn't make an API
call to do so; instead it appears to go directly to the underlying
implementation to affect a change.

Any advice here?

Thanks,
jdl
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Re: [vpp-dev] Some L2 Bridge API Questions

[Jon Loeliger]

On Tue, Mar 14, 2017 at 1:50 PM, John Lo (loj)  wrote:

> Hi Jon,
>

Hi John,


> You make a valid point about the name chosen for the API param “enable”.
> Rather than argue about the best name, let me describe how it works.
>

Sure!


> The API is intended to enable or disable an interface in L2 bridging mode.
> By disable, or enable=0, it will put the interface back to L3 mode which is
> the default mode for an interface.  If the API  is called with enable=1
> while the interface is already in L2 bridging mode, the code would actually
> perform a disable followed by enable of the interface’s current bridging
> mode as specified.
>

Ah, OK.  So at that time (the re-enable), and differing parameter
would being to take effect.  So simply re-issuing the API call
with the new parameters and an "enable" will be sufficient.

So there isn't a way to remove the bridge from the interface once
it has been associated the first time?  Or will that be accomplished
by actually removing the bridge from the bridge table?  Even if
the bridge_domain ID is left dangling on the interface?


> I take your point and will remember to update its comment in the API file,
> including fix the typo for “bridge”.
>

Thanks!
jdl
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[vpp-dev] Some L2 Bridge API Questions

[Jon Loeliger]

Hi folks,

I have a few questions about the sw_interface_set_l2_bridge API message.
Now, some people have called me a "pedantic ass", to my face even,
so I can handle that.  :-)  And I wouldn't want to disappoint, so here we
go...

>From commit 374e2c5fc30a5bfabfd2eb6c2d3ca5797402af16, line 640
of src/vpp/api/vpe.api:

   640  /** \brief Interface bridge mode request
   641  @param client_index - opaque cookie to identify the sender
   642  @param context - sender context, to match reply w/ request
   643  @param rx_sw_if_index - the interface
   644  @param bd_id - bridge domain id
   645  @param bvi - Setup interface as a bvi, bridge mode only
   646  @param shg - Shared horizon group, for bridge mode only
   647  @param enable - Enable beige mode if not 0, else set to L3 mode
   648  */
   649  define sw_interface_set_l2_bridge
   650  {
   651u32 client_index;
   652u32 context;
   653u32 rx_sw_if_index;
   654u32 bd_id;
   655u8 shg;
   656u8 bvi;
   657u8 enable;
   658  };

I want to pick on the "u8 enable" field.  First, the easy one: Line 647 has
a typo for "bridge", right?  OK, good.  But let's talk about
"enable/disable"
versus "add/del".   Is this really an enable/disable flag?  So once "added"
to the interface at rx_sw_if_index, there is no removing it?  Or did
"disable"
really remove it?  Many of the other API calls have an "is_add" field.  Is
there
really no way to remove it once added?

How is one expected to change a flag on this bridge?  For example, to
change the BVI from "false" to "true" after it has been established,
("enabled",
right?) does one just re-issue the same API call again with the new bvi
"true"
value?  Or should the bridge be "disabled", flag changed, and then
re-"enabled"?
Or even the interface shutdown, changed, and then brought back up?

Thanks,
jdl
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