On 27/11/2017 13:17, Kristian Larsson wrote:
Robert Wilton <[email protected]> writes:
Thinking about this some more. I'm not sure what it means for the "ACL
Type" to be "any-acl". It seems that the "match any packet" should be a
type of ACE, e.g. perhaps as the last entry of an ACL, rather than a
type of ACL.
Yes, I agree as so far that any-acl makes no sense as an acl-type. The
way I understood acl-type, and the way that vendors have told me it will
be used, is to say "this is an IPv4 ACL" and then on an attachment point
you can specify that only ACLs of acl-type ipv4-acl can be attached to
the interface. That makes perfect sense. I do not see how any-acl can
map into this.
I agree that any-acl is logically a type of ACE but we don't have an
ace-type and the exact same information can IMHO already be conveyed
WITHOUT the any-acl type and thus it has no reason to exist. Nor do we
need a feature for it.
>From what I can tell the any-acl container in the ACE should be used to
explicitly signify a match on "any". Think of IOS style ipv4 acl:
permit ip any any
We have to provide a source and destination so this would be a rather
explicit mapping of that. However, our structure in this YANG model is
just completely different than an IOS command so I don't see why we
should try and mimic IOS in the YANg model.
Not specifying a destination IP address means we match on any
destination IP address. The same is true for any other field we can
match on. Not setting a match implies we don't try to match on that
field, thus we allow "any" value. I think the logical continuation of
this is that for an ACE with no matches defined at all, we match any
packet. I think we can update the text to better explain this.
Otherwise if the ACL type is "any-acl" then this only allows two types
of ACLs to be defined, neither of which seem to be particularly useful:
(1) An ACL that matches all traffic and permits it, i.e. the same as
having no ACL at all.
(2) An ACL that matches all traffic and drops.
So I think perhaps the answer here is to define neither ACL type
"any-acl" nor leaf "any". The presumption could be that any ACE that is
configured to match no fields implicitly matches all packets (because
all non specified fields are treated as wildcards), and then applies the
permit/deny rule associated with the ACE. This logic can apply to all
ACL types.
Yes yes yes :)
Another area of the current model that I'm not quite convinced about is
about the L4 matches (UDP, TCP, ICMP).
Currently the model assumes that if a device can support matching on say
UDP fields that they can apply to any type of ACL. However, I think
that it is plausible that the UCP, TCP and ICMP fields might only apply
to IP ACLs and not Ethernet ACLs.
Hence, I was wondering if there should be "acl match type" identity
defined for the "l4" field matches?
This would then cause there to be twice as many ACL types identities and
features defined, e.g.
eth,
ipv4,
ipv6,
l4
eth-l4,
eth-ipv4,
eth-ipv4-l4,
eth-ipv6,
eth-ipv6-l4,
eth-ipv4-ipv6,
eth-ipv4-ipv6-l4
ipv4
ipv4-l4
ipv6
ipv6-l4,
ipv4-ipv6
ipv4-ipv6-l4
So, trading off my ACL type combinations for more expressiveness as to
what can actually be supported.
Thanks,
Rob
Kristian.
.
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