Hi,

We have been running RouterOS 3.30 to 4.1 advertising a single IPv6 prefix to our peers via BGP with no problems whatsoever; upgraded to 4.3 earlier today and noticed that our prefix was no longer being advertised.

The outbound filter applied to each IPv6 peer was:

add action=accept chain=spilsby-ipv6-out comment="" disabled=no invert-match=no prefix=2a01:568::/128 prefix-length=32 protocol=bgp
add action=discard chain=spilsby-ipv6-out comment="" disabled=no invert-match=no protocol=bgp

... and in order to get it to work, we changed it to:

add action=accept chain=spilsby-ipv6-out comment="" disabled=no invert-match=no prefix=2a01:568::/32 prefix-length=32 protocol=bgp
add action=discard chain=spilsby-ipv6-out comment="" disabled=no invert-match=no protocol=bgp

I'm not sure if the prefix-length=32 part is required now seeing as though RouterOS actually looks at the prefix length which is specified in the 'prefix' value but as it doesn't seem to complain, we have left it in.

Strangely enough, I seem to recall that specifying 'prefix=2a01:568::/32' in previous versions of RouterOS caused the rule not to match although specifying /128 seemed to work.

Also, are there any timescales for fixing WinBox so that admins can create/modify an IPv6 filter rule ?

At the moment, the prefix value is unspecified when trying to edit an existing rule and trying to put anything IPv6-like in there results in a WinBox validation error.

Regards,
Terry Froy
Spilsby Internet Solutions

what is the actual advertisement supposed to be? /128 with a prefix length /32 shouldn't have matched anything previously, so maybe it was a bug that is now fixed? The prefix length is what sizes can be announced within the prefix specified, for instance on v4 i enter prefix-length=21-24 to allow one large annoucement or smaller chunks.

what is the actual advertisement supposed to be? /128 with a prefix length /32 shouldn't have matched anything previously, so maybe it was a bug that is now fixed? The prefix length is what sizes can be announced within the prefix specified, for instance on v4 i enter prefix-length=21-24 to allow one large annoucement or smaller chunks.

It is supposed to be a single /32.

Having re-read the official docs, you are correct; our previous filter rule should have failed to work with previous versions of RouterOS but nevertheless, it did work.

I am mindful that the changelogs for RouterOS are notable for their lack of detail and while additional functionality should be detailed in them so that people know that it exists and can consider whether it is worthwhile to upgrade; fixes to minor 'bugs' like this which may require a config review by the admin should at least get a one-liner in the changelog (or a hyperlink to a list of minor bugs which have been squished).

Regards,
Terry Froy
Spilsby Internet Solutions