Re: [v6ops] I-D Action: draft-ietf-v6ops-ipv6-ehs-packet-drops-00 - Middleboxes

Fernando Gont <> Mon, 03 August 2020 10:37 UTC

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To: Vasilenko Eduard <>, "" <>
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From: Fernando Gont <>
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Date: Mon, 3 Aug 2020 07:36:20 -0300
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Subject: Re: [v6ops] I-D Action: draft-ietf-v6ops-ipv6-ehs-packet-drops-00 - Middleboxes
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Hello, Eduard,

On 1/8/20 13:45, Vasilenko Eduard wrote:
> I am still not happy that middleboxes (Firewall, Load Balancer) are 
> discarded as the reasons for EH drops.

FWIW, we will include a discussion of these in the next revision of the 
document -- please bear with us. :-)

> It is especially evident that they are among reasons for EHs drops after 
> response:
>  > I would love to see the firewall device that is capable of processing 
> ALL protocol headers in the IETF protocol suite! *Reality is that 
> firewalls can only process what they are programmed to process which is 
> typically a very small subset of the possible protocols a host might 
> want to use.*

Please note that this is somewhat mixing up two different issues issues:

1) The ability to process packets

2) A filtering policy

Firewalls, by definition, must perform #2. And quite normally they can 
do fragment reassembly, and even inspect packets above layer-4. In many 
cases, even if they can process a packet, they may drop the packet as a 
result of the filtering policy (e.g., default deny, which is typical 
among firewalls) -- i.e., only allow the traffic you are expected to 
receive. This obviously happens at the destination AS, close to the 
destination system.

OTOH, many devices (such as modern routers) may have an operational 
requirement of doing things (Sections 6.2-6.4), and packets with EHs get 
in the way. It's not that they are meant to do a default-deny (in many 
cases, they actually implement a default-allow policy), but packets with 
EHs put them in a position that they cannot even perform a "default 
allow" policy, and hence they need to be dropped.

Fernando Gont
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