Re: [bess] Question on IRB MAC in draft-ietf-bess-evpn-inter-subnet-forwarding

[Muthu Arul Mozhi Perumal <[e-mail]>]

Hi authors, EVPN experts,

Any feedback?

Regards,
Muthu

On Tue, Mar 19, 2019 at 4:00 PM Muthu Arul Mozhi Perumal <
[e-mail]> wrote:

> draft-ietf-bess-evpn-inter-subnet-forwarding describes two ways of
> provisioning the default gateway MAC and IP addresses on the IRB interface
> associated with the corresponding subnet:
>
> <snip>
>    1. All the PEs for a given tenant subnet use the same anycast default
>    gateway IP and MAC addresses . On each PE, this default gateway IP
>    and MAC addresses correspond to the IRB interface connecting the BT
>    associated with the tenant's VLAN to the corresponding tenant's IP-
>    VRF.
>
>    2. Each PE for a given tenant subnet uses the same anycast default
>    gateway IP address but its own MAC address. These MAC addresses are
>    aliased to the same anycast default gateway IP address through the
>    use of the Default Gateway extended community as specified in
>    [RFC7432], which is carried in the EVPN MAC/IP Advertisement routes.
> </snip>
>
> Further below it says:
>
> <snip>
>    Irrespective of using only the anycast address or both anycast and
>    non-anycast addresses on the same IRB, when a TS sends an ARP request
>    or ND Neighbor Solicitation (NS) to the PE that is attached to, the
>    request is sent for the anycast IP address of the IRB interface
>    associated with the TS's subnet and the reply will use anycast MAC
>    address (in both Source MAC in the Ethernet header and Sender
>    hardware address in the payload).
> </snip>
>
> In the above, it says the ARP response or NS will use the anycast MAC
> address. The question is, how is this feasible if the second option of provisioning
> the default gateway MAC and IP addresses on the IRB interface are chosen,
> where each PE for a given tenant subnet uses the same anycast default
> gateway IP address but its own MAC address?
>
> Should it instead say:
>   the request is sent for the anycast IP address of the IRB interface
>    associated with the TS's subnet and the reply will use *configured*
>    MAC address?
>
> i.e. s/anycast MAC/configured MAC?
>
> Regards,
> Muthu
>