RE: MAC route with IP

[Jakob Heitz <[e-mail]>]

People clear ARP caches when they get too big. When that happens, the bridge table may not be cleared at the same time or at all.
An ARP cache may have a different timeout than the bridge table.
A bridge can snoop ARP messages to learn bindings and those bindings can time out.
However, many other packets can come from the same MAC address, keeping the MAC alive in the bridge table. In this case, the MAC-IP binding will be lost without the MAC address itself being lost.
IP-MAC bindings can be learnt other than by snooping ARPs, by configuration, for example.
Such configurations can be removed.

Cheers,
Jakob.

From: L2vpn [mailto:[e-mail]] On Behalf Of Jakob Heitz
Sent: Sunday, May 11, 2014 10:39 PM
To: Ali Sajassi (sajassi); [e-mail]
Cc: Antoni Przygienda
Subject: RE: MAC route with IP

When the IP address is dissociated with the MAC address, but the MAC address still exits.

Cheers,
Jakob.

From: Ali Sajassi (sajassi) [mailto:[e-mail]]
Sent: Sunday, May 11, 2014 10:34 PM
To: Jakob Heitz; [e-mail]<mailto:[e-mail]>
Cc: Antoni Przygienda
Subject: Re: MAC route with IP


Hi Jakob,

I believe the currency text is correct and sufficient. What use case do you have in mind?

EVPN PE devices that only do L2 (w/ flooding), only advertise MAC route (w/o IP address) and EVPN PE devices that do L2 w/ ARP suppression, advertise both MAC and IP. In the latter case, if there are several IP addresses map to the same MAC address, then the MAC address from MAC-VRF only gets removed, when there is no more ARP entry with that MAC address.

Cheers,
Ali

From: Jakob Heitz <[e-mail]<mailto:[e-mail]>>
Date: Sunday, May 11, 2014 9:56 PM
To: "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>
Cc: Antoni Przygienda <[e-mail]<mailto:[e-mail]>>
Subject: MAC route with IP

We have another issue
In section 10: ARP and ND, the draft says:

   If there are multiple IP addresses associated with a MAC address,
   then multiple MAC advertisement routes MUST be generated, one for
   each IP address. For instance, this may be the case when there are
   both an IPv4 and an IPv6 address associated with the MAC address.


   When the IP address is dissociated with the MAC address, then the MAC

   advertisement route with that particular IP address MUST be

   withdrawn.

If such a route is withdrawn and no MAC route without IP exists, then the MAC address will be forgotten. Therefore, we would like to add a sentence:

Whenever a PE advertises one or more MAC advertisement routes with IP address for a particular MAC address, it MUST also advertise one MAC advertisement route without an IP address for that MAC address.

Thanks,
Jakob.