Lucy, David,
The proposed text says that outcome 3c) is unacceptable but highly unlikely.
For example, assume the following:
- That an IPv6 address is assigned to every milligram of matter on
earth, including every drop of water. (2**95 IPv6 addresses are assigned)
- That every minute, the destination address on a delivery packet is
corrupted
- The pattern of corruption is random
Every time a destination address is corrupted, the odds are 1 / 8,589,934,592
that the result will be an assigned address. This should happen one ever 16,
331 years.
Now, assume that only 1% of those of those 2**95 IPv6 addresses are configured
on devices that de-encapsulate GRE. In this case, outcomes 3a), 3b) and 3c)
will occur only once every 1,633,100 years!
So, practically speaking, we don’t have much to worry about. But for the
purposes of the pedantry, we may need to say that GRE over IPv6 is only
practical when operators can deal with that risk.
David, what is the minimum text that we can import to satisfy the requirement.
Ron
From: Lucy yong [mailto:[email protected]]
Sent: Tuesday, March 31, 2015 3:21 PM
To: Ronald Bonica; Black, David; [email protected]; [email protected]
Cc: [email protected]; [email protected]
Subject: RE: Start of WGLC for draft-ietf-intarea-gre-ipv6
Hi Ron,
3c) may happen for a VPN or non-VPN case. The payload can be in non-IPv6 space.
Is “Outcome 3c) is not acceptable, but it extremely unlikely.” for particular
network/usage in your mind?
Is the goal here to prove such corruption is acceptable or extreme unlikely?
Regards,
Lucy
From: Int-area [mailto:[email protected]] On Behalf Of Ronald Bonica
Sent: Tuesday, March 31, 2015 1:43 PM
To: Black, David; [email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>
Cc:
[email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>
Subject: Re: [Int-area] Start of WGLC for draft-ietf-intarea-gre-ipv6
Resend…
From: Ronald Bonica
Sent: Tuesday, March 31, 2015 2:23 PM
To: 'Black, David'; [email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>
Cc:
[email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>
Subject: RE: Start of WGLC for draft-ietf-intarea-gre-ipv6
David, Lucy,
You are correct. Maybe the following text will address the issue:
OLD>
Because the IPv6 delivery header does not include a checksum of its
own, it is subject to corruption. However, even if the delivery
header is corrupted, to likelihood of that corruption resulting in
misdelivery of the payload is extremely low.
<OLD
NEW>
Because the IPv6 delivery header does not include a checksum of its
own, the destination address in the delivery header is subject to
corruption. If the destination address in the deliver header is corrupted,
the following outcomes are possible:
1) The delivery packet is dropped because the new destination address is
unreachable
2) The delivery packet is dropped because the new destination address is
reachable, but that node is not configured to process GRE delivery packets from
the ingress
3) The delivery packet is processed by a GRE egress other than that which
was originally specified by the GRE ingress. Processing options are:
a. The payload packet is dropped because the payload destination is
unreachable from the node that processed the delivery packet
b. The payload packet is delivered to its intended destination
c. The payload packet is erroneously delivered to a node other than its
intended destination. The intended destination and the node to which the
payload is actually delivered are numbered identically, but reside in different
VPNs.
Outcomes 1), 2), 3a) and 3b) are acceptable. Outcome 3c) is not acceptable, but
it extremely unlikely. Because IPv6 address space is so large and so sparsely
populated, outcome 1) is by far the most probable. Therefore, the combined
likelihood of all acceptable outcomes by far exceeds the likelihood of the one
unacceptable outcome.
Furthermore, even if the payload is erroneously delivered to a node other than
its intended destination, that node will discard the packet if the payload is
also corrupted or if there are no applications waiting to consume the packet.
<NEW
Ron
From: Black, David [mailto:[email protected]]
Sent: Monday, March 30, 2015 7:48 PM
To: Ronald Bonica; [email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>
Cc:
[email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>; Black, David
Subject: RE: Start of WGLC for draft-ietf-intarea-gre-ipv6
> Also, why would you object to 3b? The packet ends up at the right node, just
> via an unexpected route.
That assertion is based on the assumption that the payload destination address
is worldwide unique.
There are lots of counterexamples that void the assumption, e.g., 10.0.0.0/8.
Thanks,
--David
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