Re: MAC route with IP

["Ali Sajassi (sajassi)" <[e-mail]>]

Antoni,

From: Antoni Przygienda <[e-mail]<mailto:[e-mail]>>
Date: Sunday, May 11, 2014 11:23 PM
To: Cisco Employee <[e-mail]<mailto:[e-mail]>>, Jakob Heitz <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>
Subject: RE: MAC route with IP

Ali,

there are at least two cases when receiving updates from peers which are tad hairy given the encoding:


1.      We receive a MAC/no-IP  & a set of MAC/IP routes & then someone just withdraws the MAC/no-IP.  It does not seem very logical that the MAC/IP routes are still valid to me or at least that could be emphasized in the draft that they do (i.e. all routes are truly independent).

MAC/IP routes will be independent from MAC-only route. If both are advertised, then withdrawing the MAC/IP route should clean up the ARP table but not remove the entry in the MAC-VRF.


2.      Since we have mac based disposition there is nothing that prevents a neighbor to advertise multiple MAC/IP routes with different labels.  It should obviously not imply that we have to lookup the IP address on the packet (if we even have one) to decide which label is needed.  Should all this labels be considered pointing to the same MAC & equivalent ? Such a condition considered invalid transient and MAC labels for this MAC ignored completely ?  What if we get one route with the label & another without ? We use the label nevertheless for the same MAC ?

The label represents the MAC address in case of label per MAC advertisement. So, even when you advertise multiple IP addresses for the same MAC, they all should use the same label.

And my final interesting observation:

               A single primary/single backup case would be simple & easy, the way the protocol spec stands today, I don’t think there is anything that prevents it from operating in  multiple-primaries, multiple-backup mode  (as in two guys clear the single-active bits & all other set them) [unless I misunderstood something massively].   Do we load balance the primaries until both fail & then either flood (multiple backups) or fail back on the secondary ?

For a given ES, all PEs should advertise the same redundancy group mode (either all-active or single-active mode) for that ES. Otherwise, an error should be logged.

Cheers,
Ali

Otherwise, very good draft I think solving tons of hard problems in (for the customer and in terms of protocols mechanics) fairly elegant way.

--- tony
From: Ali Sajassi (sajassi) [mailto:[e-mail]]
Sent: Sunday, May 11, 2014 10:53 PM
To: Jakob Heitz; [e-mail]<mailto:[e-mail]>
Cc: Antoni Przygienda
Subject: Re: MAC route with IP


Yes, but that's the case when that MAC address is associated with other IP addresses per my example below. And as long as there are other ARP entry (or entries) for that MAC address after deleting that IP/MAC pair, the MAC address will remain in the MAC-VRF.

Cheers,
Ali

From: Jakob Heitz <[e-mail]<mailto:[e-mail]>>
Date: Sunday, May 11, 2014 10:38 PM
To: Cisco Employee <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>
Cc: Antoni Przygienda <[e-mail]<mailto:[e-mail]>>
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.