On 4/15/15 11:25 PM, Robert Raszuk wrote:
Ok I think there are two scenarios.
The original scenario I had in mind was indeed the loopback anycast
which would really not have any issues with arp.
The other scenario is NIC overload with multiple addresses some of
them would be anycast. It is in fact not that uncommon to have an
identical VMs with same IP for robustness without LB. I am not sure if
we need to *solve* it at ARP, but we do need to consider it as a valid
case and not react as far as duplicate address detection is concerned.
Again here depending on the implementation if you put both such VMs
say in different VRFs you have no ARP issue, but anycast works fine.
Robert,
The case of a dual-NIC server is typically solved locally (using e.g.,
multi-chassis LAG for redundancy), and AFAIK the same MAC address is
used (but I haven't looked at all the flavors of Linux NIC bonding and
VmWare options).
I think to proceed I would be happy to see those cases just documented
in deployment section of the draft and we move on. I do not think that
solving or even touching IPv4 ARP is needed here at this point.
Agreed.
Or perhaps a different comment to add to the draft would be to mention
that duplicate IPv4 address detection is scoped to the same ARP table
(which may not be the same as same subnet :).
That seems like a useful addition (if it isn't already in this or some
other document).
Erik
Cheers,
r.
On Thu, Apr 16, 2015 at 12:44 AM, Erik Nordmark <nordm...@acm.org
<mailto:nordm...@acm.org>> wrote:
On 4/15/15 2:53 PM, Robert Raszuk wrote:
Erik,
How about /32 IPv4 anycast addresses with multiple subnet per
linux NIC ? It is typical to be able to overload host
networking with same anycast loopbacks.
I guess "same subnet" isn't sufficient as criteria - "same subnet
which corresponds to a connected route" would be one way to phrase
the constraint.
It does not need to be ARP resolved .. the resolution is
indirect via connected next hops.
Yes, that is the key issue.
For instance host routes (/32) and an anycast address on a
loopback interface works fine in IPv4 and IPv6.
Erik
Cheers,
R.
On Wed, Apr 15, 2015 at 11:48 PM, Erik Nordmark
<nordm...@acm.org <mailto:nordm...@acm.org>
<mailto:nordm...@acm.org <mailto:nordm...@acm.org>>> wrote:
On 3/31/15 1:10 PM, Rabadan, Jorge (Jorge) wrote:
Hi Robert and Tony,
As Wim mentioned, ipv6 anycast is something that we
will add
to the draft in the next rev. There is an easy way to
know if
a given proxy-ND entry belongs to an anycast address
or not
and disable the duplicate IP detection for those.
The challenge for IPv4 is that I don’t see an easy way to
learn _dynamically_ from access attachment circuits that a
given ipv4 is anycast. Even for default gateways, if
they are
integrated in the EVPN PE, we are good, but if they are
external and connected to a MAC-VRF, it is not so
clear how to
learn that (unless you learn those entries from the
management
interface).
Jorge,
IPv4/ARP doesn't have any support for anycast address on
the same
subnet. While IPv6/ND has such support (using the O-flag) the
common anycast deployment for both is to have the anycast
instances deployed on different subnets and, in the case
of DNS
servers, in different ISPs.
Thus for IPv4 I think you can assume that the same IP address
appearing with different MAC addresses is either a
duplicate IP
address or a case of a host having changed the MAC address
on its
NIC. (I don't know if NIC bonding can be configured in a
way where
it looks like an IP->MAC change each time there is a
failure; if
so that would be a third case.)
Erik
One of the reasons why we have lots of “SHOULDs” in
the draft
and not “MUST” is because the implementation has to be
flexible enough to be configured in a different way
depending
on the use-case, which is one of the points that Tony
mentions
below. In the use-case described at the moment there is no
anycast and duplicate IP detection is very important.
We will
add the DC use case in the next rev as suggested by
Robert and
others.
Thanks.
Jorge
From: Antoni Przygienda
<antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>>>>
Date: Monday, March 30, 2015 at 12:12 AM
To: Robert Raszuk <rob...@raszuk.net
<mailto:rob...@raszuk.net>
<mailto:rob...@raszuk.net <mailto:rob...@raszuk.net>>
<mailto:rob...@raszuk.net <mailto:rob...@raszuk.net>
<mailto:rob...@raszuk.net
<mailto:rob...@raszuk.net>>>>, "Henderickx, Wim (Wim)"
<wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>>>>
Cc: Erik Nordmark <nordm...@acm.org
<mailto:nordm...@acm.org> <mailto:nordm...@acm.org
<mailto:nordm...@acm.org>>
<mailto:nordm...@acm.org <mailto:nordm...@acm.org>
<mailto:nordm...@acm.org <mailto:nordm...@acm.org>>>>,
"bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>
<mailto:bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>>"
<bess@ietf.org <mailto:bess@ietf.org> <mailto:bess@ietf.org
<mailto:bess@ietf.org>>
<mailto:bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>>>, Jorge Rabadan
<jorge.raba...@alcatel-lucent.com
<mailto:jorge.raba...@alcatel-lucent.com>
<mailto:jorge.raba...@alcatel-lucent.com
<mailto:jorge.raba...@alcatel-lucent.com>>
<mailto:jorge.raba...@alcatel-lucent.com
<mailto:jorge.raba...@alcatel-lucent.com>
<mailto:jorge.raba...@alcatel-lucent.com
<mailto:jorge.raba...@alcatel-lucent.com>>>>
Subject: RE: [bess] ARP ND draft
I’m also skeptical whether IP duplicate detection
would be
a good
default thing. Especially in case of what I call
‘aliased
default
gateway’ which section 10.1 specifically allows, i.e.
default GW
IP address is same but each PE may use a different
MAC when
advertising it and consequently responses for same
IP with
different ARPs may be seen in the network. Yes,
default GW
ExtComm is there to differentiate so it can be
called an
exception
but nevertheless.
I also thought a tad about VRRP but I think the IP
duplicate
detection will not apply there, it’s all same
IPx->MACx
from all
routers so if anything, it’s more of a MAC move thing.
Generally I think someone who wants a secure,
stable eVPN
wants IP
duplicate detection, someone who runs a very dynamic
network with
tons gateways, possibly anycast & floating IPs will
probably not
be too enamored with it.
Thanks
--- tony
//
/There are basically two types of people. People who
accomplish
things, and people who claim to have accomplished
things. The
first group is less crowded.
<http://www.brainyquote.com/quotes/quotes/m/marktwain393535.html>/
/~~~ Mark Twain
<http://www.brainyquote.com/quotes/quotes/m/marktwain393535.html>/
*From:*rras...@gmail.com
<mailto:rras...@gmail.com> <mailto:rras...@gmail.com
<mailto:rras...@gmail.com>>
<mailto:rras...@gmail.com <mailto:rras...@gmail.com>
<mailto:rras...@gmail.com <mailto:rras...@gmail.com>>>
[mailto:rras...@gmail.com
<mailto:rras...@gmail.com> <mailto:rras...@gmail.com
<mailto:rras...@gmail.com>>] *On
Behalf Of *Robert Raszuk
*Sent:* Monday, March 30, 2015 1:19 AM
*To:* Henderickx, Wim (Wim)
*Cc:* Erik Nordmark; Antoni Przygienda;
bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>
<mailto:bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>>; Rabadan,
Jorge (Jorge)
*Subject:* Re: [bess] ARP ND draft
Hi Wim,
> There is anycast at IPv4 level for sure but I am not
ware this is
supported at arp level.
Precisely right. It needs to be documented and
addressed
if anyone
is up to proposing automated IP duplicate address
detection and
disabling.
RFC1546 is rather too old to consider here as
solution :)
Cheers,
R.
On Mon, Mar 30, 2015 at 1:10 AM, Henderickx, Wim (Wim)
<wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>>>> wrote:
To be clear: RFC4861 section 7.2.7 explains the
anycast
behaviour
in IPv6.
I am not aware of such thing at IPv4/ARP level. Do you
have a pointer?
There is anycast at IPv4 level for sure but I am
not ware
this is
supported at arp level.
*From: *<Henderickx>, Wim Henderickx
*Date: *Monday 30 March 2015 07:38
*To: *Robert Raszuk
*Cc: *Erik Nordmark, Antoni Przygienda,
"bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>
<mailto:bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>>", Jorge Rabadan
*Subject: *Re: [bess] ARP ND draft
At interface level you get dad in most stacks I know.
Sent from my iPhone
On 30 Mar 2015, at 06:45, Robert Raszuk
<rob...@raszuk.net <mailto:rob...@raszuk.net>
<mailto:rob...@raszuk.net <mailto:rob...@raszuk.net>>
<mailto:rob...@raszuk.net
<mailto:rob...@raszuk.net> <mailto:rob...@raszuk.net
<mailto:rob...@raszuk.net>>>> wrote:
Hi Wim,
What makes you say that in IPv4 there is no
anycast ? All
anycase I have played so far is IPv4 :)
Cheers,
r.
On Sun, Mar 29, 2015 at 11:18 PM, Henderickx,
Wim (Wim)
<wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>>>> wrote:
We will update the draft to highlight the IPv6
anycast
behaviour better as pointed out by RObert. In IPv4
there is no
anycast behaviour and as such there should be one
option possible.
On 30/03/15 04:59, "Antoni Przygienda"
<antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>>>> wrote:
>Yes, but of course I brought it up to show
that 'the
last one
simply wins' as suggested by the draft is not
enough
IMO. A
good architecture should probably keep track
of what
it served
as answer and when the answer is invalid or a new,
better one
exists, provide a GARP.
>
>As well, when PE2 sends a newer MAC it may
not be a good
strategy to serve a GARP if PE1's MAC has
already been
offered. That could lead IMO to e.g. gateway
chasing
problems.
>
>--- tony
>
>
>There are basically two types of people.
People who
accomplish things, and people who claim to have
accomplished
things. The first group is less crowded.
>~~~ Mark Twain
>
>
>> -----Original Message-----
>> From: Henderickx, Wim (Wim)
[mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>
<mailto:wim.henderi...@alcatel-lucent.com
<mailto:wim.henderi...@alcatel-lucent.com>>>]
>> Sent: Thursday, March 26, 2015 6:01 AM
>> To: Antoni Przygienda; Erik Nordmark; Rabadan,
Jorge (Jorge)
>> Cc: bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>
<mailto:bess@ietf.org <mailto:bess@ietf.org>
<mailto:bess@ietf.org <mailto:bess@ietf.org>>>
>> Subject: Re: [bess] ARP ND draft
>>
>> For this case you should sent a GARP with
the new
MAC/IP
>>
>>
>>
>>
>> On 25/03/15 18:56, "Antoni Przygienda"
<antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>
<mailto:antoni.przygie...@ericsson.com
<mailto:antoni.przygie...@ericsson.com>>>>
>> wrote:
>>
>> >> > b)It is worth explaining what is suggested
behavior if
eVPN
>> >> > advertises the same IP with multiple
MACs and what
happens when
>> >> > e.g. the served MAC vanishes
>> >> >
>> >> Doesn't the EVPN RFC already stating
that the routes
would be
>> >> withdrawn in that case?
>> >
>> >The scenario I had in mind was when eVPN
PE receives
>> >
>> >From PE2 IP1/M1 and later
>> >From PE3 IP1/M2
>> >
>> >while having answered with IP1/M1 per
proxy alrady.
Additionally, in
>> >such situation ends up seeing
>> >
>> >From PE2 IP1/<no MAC>
>> >
>> >So the answer it gave is not valid anymore
all of
a sudden.
>> >
>> >--- tony
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