bgpd: add bgp ipv6-auto-ra command by Sokolmish · Pull Request #16354 · FRRouting/frr

Sokolmish · 2024-07-07T22:15:27Z

Introduce a command to completely disable sending IPv6 router advertisement messages on an interface. Before, there were cases where it could be enabled by other daemons, namely bgpd and vrrpd. Particularly, it happens when BGP extended-nexthop capability is used: bgpd tells zebra to enable RA in this case, though it wasn't intended.

Fixes #7738.

Sokolmish · 2024-07-07T22:29:45Z

I apologize. I work with an older version of FRR, so I have messed up a bit with syncing changes between it and this PR. Fixed it now.

ton31337

Maybe shouldn't allow sending RAs or at least giving a warning (zlog_warn) to the operator that for example BGP unnumbered won't work if because you have RAs disabled?

Sokolmish · 2024-07-08T22:11:21Z

Maybe shouldn't allow sending RAs or at least giving a warning (zlog_warn) to the operator that for example BGP unnumbered won't work if because you have RAs disabled?

Hello. Do you mean that the message should be printed in bgpd in an attempt to add an unnumbered peer? Or on any request to zebra (in zebra_interface_radv_set())?

The first case is similar to what I wanted to do initially: point out all calls from bgpd that enable RA (bgp_zebra_initiate_radv()/zclient_send_interface_radv_req()) and are not related to unnumbered peers, but I wasn't able to determine which calls are related to it and which are not.

The second case is easy, but it seems that it might create some misleading warnings in the case of RA not being intended. E.g., we use the extended-nexthop capability for SRv6 and don't need RA but will still get the warnings. Maybe reduce the level to, say, info?

ton31337 · 2024-07-09T08:14:13Z

Do you mean that the message should be printed in bgpd in an attempt to add an unnumbered peer?

I'm trying to understand why we should allow sending RAs by any other protocol if we have it explicitly disabled per-interface level?

Sokolmish · 2024-07-09T09:57:40Z

As far as I understood, before this PR there were 2 states: RA explicitly enabled (no suppress-ra) and default state (suppress-ra) overridable by other daemons. So I've added the explicitly disabled state (disable-ra).

Other daemons don't look at the state from vty and just send ZEBRA_INTERFACE_ENABLE_RADV to zebra. Bgpd enables RA in case of extended-nexthop capability being enabled in several places (e.g., on initialization or when new nexthop is got). VRRP enables RA when the router becomes active.

I don't think we should fail these operations because of disabled RA because it isn't the primary thing there: extended-nexthop (and VRRP, I guess) can work without RA. Unnumbered peers most probably won't (I'm not quite familiar with it), and it might be better to fail a command or print a warning in such case, but it will require determining which calls to radv_enable() in bgpd are purely for unnumbered peers, aside from getting the zebra's radv flags from bgpd.

eqvinox · 2024-07-10T07:04:11Z

I agree we need this feature, I've been burned by this myself before.

However, I'm not sure zebra is the correct place for this, especially after looking at the vrrpd use case.

bgpd: enables RA for use by BGP to find the neighbor router. Can be very unexpected and is an abuse of the protocol (should never have been designed like this.) It will be common to have no RA configuration, so the RAs are sent with default parameters.
vrrpd: enables RA for the RA function itself, i.e. telling clients. It just limits RA based on the VRRP role, so that only the primary router sends RAs. In this case the RAs will normally be configured by the admin and have correct settings, and they are expected and wanted.

The switch in zebra tries to fix the problem without distinguishing these two cases. It theoretically breaks VRRP use of this function.

⇒ I think this needs to be switched in bgpd, not zebra.

eqvinox

I strongly believe this switch should be moved into bgpd instead.

Sokolmish · 2024-07-11T22:04:05Z

I've added a new option to bgpd. Used the preserve-fw-state option as a template for VTY command and flag handling.

ton31337 · 2024-07-14T00:16:37Z

bgpd/bgp_zebra.c


 void bgp_zebra_terminate_radv(struct bgp *bgp, struct peer *peer)
 {
+	/*


Abandoned comment?

Removed it.

ton31337 · 2024-07-14T00:20:17Z

bgpd/bgp_vty.c

+	return CMD_SUCCESS;
+}
+
+DEFUN (bgp_ipv6_auto_ra,


DEFPY please, and please combine into a single DEFPY for both forms ([no] bgp ipv6-auto-ra).

bgpd/bgp_vty.c

Sokolmish · 2024-07-15T19:40:05Z

I keep getting random topotests failed in modules I haven't touched in the PR (now it's MSDP, before it was OSPF, PIM). Is it the infrastructure problem, or am I missing something?

riw777

looks good ... waiting on other comments to be cleared and running failed test

ton31337 · 2024-07-16T14:47:27Z

bgpd/bgp_nht.c

 	bgp = peer->bgp;
+
+	/* Shouldn't enable RA if they are disabled */
+	assert(!CHECK_FLAG(bgp->flags, BGP_FLAG_IPV6_NO_AUTO_RA));


I doubt on this assert, why is this needed? Can't be handle it more gracefully?

This function is called from only one place that is already covered by checking the flag, so I thought about making an assert there. Now I've changed it to a regular check with early return.

ton31337

LGTM

riw777 · 2024-08-06T12:35:27Z

I strongly believe this switch should be moved into bgpd instead.

I think this is done now (?) ... @eqvinox can you take a look to see if this okay?

riw777 · 2024-08-27T14:19:42Z

@eqvinox ping :-)

riw777 · 2024-09-24T13:47:41Z

@eqvinox ping :-)

github-actions · 2024-09-24T14:49:10Z

This pull request has conflicts, please resolve those before we can evaluate the pull request.

Introduce a command to stop bgpd from enabling IPv6 router advertisement messages sending on interfaces. Signed-off-by: Mikhail Sokolovskiy <sokolmish@gmail.com>

outdated

eqvinox · 2024-10-28T12:29:19Z

@Mergifyio backport dev/10.2 stable/10.1 stable/10.0 stable/9.1 stable/9.0 stable/8.5 stable/8.4

mergify · 2024-10-28T12:29:27Z

backport dev/10.2 stable/10.1 stable/10.0 stable/9.1 stable/9.0 stable/8.5 stable/8.4

✅ Backports have been created

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#17265 bgpd: add bgp ipv6-auto-ra command (backport #16354) has been created for branch dev/10.2
#17267 bgpd: add bgp ipv6-auto-ra command (backport #16354) has been created for branch stable/10.1 but encountered conflicts
#17266 bgpd: add bgp ipv6-auto-ra command (backport #16354) has been created for branch stable/10.0 but encountered conflicts
#17268 bgpd: add bgp ipv6-auto-ra command (backport #16354) has been created for branch stable/9.1 but encountered conflicts
#17269 bgpd: add bgp ipv6-auto-ra command (backport #16354) has been created for branch stable/9.0 but encountered conflicts
#17270 bgpd: add bgp ipv6-auto-ra command (backport #16354) has been created for branch stable/8.5 but encountered conflicts
#17271 bgpd: add bgp ipv6-auto-ra command (backport #16354) has been created for branch stable/8.4 but encountered conflicts

bgpd: add bgp ipv6-auto-ra command (backport #16354)

New Features Highlight: - PIM candidate BSR/RP [#16438] - Static IGMP join without an IGMP report [1#6450] - PIM AutoRP discovery/announcements [#16634] - IGMP proxy [#16861] - SRv6 SID Manager [#15604] - Add `bgp ipv6-auto-ra` command [#16354] - Implement `neighbor x remote-as auto` for BGP [#16345] - Implement `bgp dual-as` for BGP [#16816] - Implement BGP-wide configuration for graceful restart [#16099] - Handle kernel routes appropriately (should fix recent NOPREFIXROUTE issue) [#16300] - Add `cisco-authentication` password support for NHRP [#16172] Signed-off-by: Jafar Al-Gharaibeh <jafar@atcorp.com>

frrbot bot added the zebra label Jul 7, 2024

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Sokolmish force-pushed the zebra-no-ra branch from 80b9f0d to 9f8ee1b Compare July 7, 2024 22:23

Sokolmish force-pushed the zebra-no-ra branch from 9f8ee1b to 1d07dba Compare July 7, 2024 22:31

ton31337 reviewed Jul 8, 2024

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Sokolmish force-pushed the zebra-no-ra branch from 1d07dba to 207a867 Compare July 11, 2024 21:14

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Sokolmish changed the title ~~zebra: add ipv6 nd disable-ra command~~ bgpd: add bgp ipv6-auto-ra command Jul 11, 2024

Sokolmish force-pushed the zebra-no-ra branch from 207a867 to 9aceceb Compare July 11, 2024 21:36

Sokolmish force-pushed the zebra-no-ra branch from 9aceceb to b99c845 Compare July 13, 2024 20:15

ton31337 requested changes Jul 14, 2024

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Sokolmish force-pushed the zebra-no-ra branch 2 times, most recently from d5aa081 to 02a6900 Compare July 15, 2024 18:28

Sokolmish force-pushed the zebra-no-ra branch from 02a6900 to ddf909e Compare July 15, 2024 19:52

riw777 approved these changes Jul 16, 2024

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ton31337 reviewed Jul 16, 2024

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Sokolmish force-pushed the zebra-no-ra branch from ddf909e to 4e9ceee Compare July 16, 2024 19:02

eqvinox self-requested a review July 17, 2024 16:39

ton31337 approved these changes Jul 22, 2024

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donaldsharp self-requested a review July 23, 2024 15:22

github-actions bot added the conflicts label Sep 24, 2024

bgpd: add bgp ipv6-auto-ra command

7b1c0c2

Introduce a command to stop bgpd from enabling IPv6 router advertisement messages sending on interfaces. Signed-off-by: Mikhail Sokolovskiy <sokolmish@gmail.com>

Sokolmish force-pushed the zebra-no-ra branch from 4e9ceee to 7b1c0c2 Compare September 24, 2024 16:01

github-actions bot removed the conflicts label Sep 24, 2024

ruben-herold mentioned this pull request Oct 10, 2024

Zebra sends Router Advertisements when the extended-nexthop capability is enabled, also without unnumbered BGP #17051

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eqvinox approved these changes Oct 28, 2024

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eqvinox merged commit e4df480 into FRRouting:master Oct 28, 2024

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Jafaral added a commit that referenced this pull request Oct 28, 2024

Merge pull request #17265 from FRRouting/mergify/bp/dev/10.2/pr-16354

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bgpd: add bgp ipv6-auto-ra command (backport #16354)

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