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nexthop group extensions #15038

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nexthop group extensions #15038

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Commits on Jan 22, 2024

  1. zebra: rework zebra_nhg_proto_add() parameters 

    This small rework prepares next commit.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  2. sharpd, zebra, lib, doc: add recursive support for protocol nhid 

    In sharpd, configuring a nexthop-group with an IP nexthop that is not
directly connected does not create a NHG context in zebra:

> ubuntu2204(config)# interface loop1
> ubuntu2204(config-if)# ip address 192.0.2.1/24
> ubuntu2204(config-if)# exi
> ubuntu2204(config)# ip route 192.168.0.0/24 192.0.2.100
> ubuntu2204(config)# nexthop-group ABCD
> ubuntu2204(config-nh-group)# nexthop 192.168.0.100
> 2024/01/17 16:36:23 SHARP: [Y2G2F-ZTW6M] nhg_add: nhg 181818169 not sent: no valid nexthops
> ubuntu2204(config-nh-group)# do show nexthop-group rib 181818169
> Nexthop Group ID: 181818169 does not exist

Nexthops with an undefined interface index are neither handled
in ZEBRA, nor in SHARPD.

On the other hand, if we had created a route pointing to the same
nexthop (by using ZEBRA_ROUTE_ADD zapi), the next-hop would have been
installed, thanks to the ALLOW_RECURSION flag embedded in the zapi_route
structure.

Add the support for recursivity in nexthop groups by introducing
a flags attribute in the nexthop group structure. Define the
NEXTHOP_GROUP_ALLOW_RECURSION value, which will be used by ZEBRA to
check for the next-hop group recursivity. This flag will be set when
the 'allow-recursion' command will be used:

> ubuntu2204(config)# nexthop-group ABCD
> ubuntu2204(config-nh-group)# allow-recursion
> ubuntu2204(config-nh-group)# nexthop 192.168.0.100
> 2024/01/17 16:57:44 SHARP: [JWRCN-N9K90] Installed nhg 181818168
> ubuntu2204(config-nh-group)# do show nexthop-group rib 181818168
> ID: 181818168 (sharp)
>      RefCnt: 1
>      Uptime: 00:00:10
>      VRF: default
>      Valid, Installed
>      Depends: (73)
>         via 192.168.0.100 (vrf default) (recursive), weight 1
>            via 192.0.2.100, loop1 (vrf default), weight 1

This flag control is mandatory, as the recursivity may not be allowed
by protocols like eBGP single-hop.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  3. topotests: add nexthop-group allow-recursion test 

    Add a nexthop group test that ensures that a recursive
next-hop is resolved in zebra.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  4. sharpd, lib: add force-nexthop-config option to sharp in NHG 

    In BGP, it is possible to push an eBGP route without using the
ALLOW_RECURSION flag in the route flags option.

In SHARP, it is possible to do the same with the 'sharp install route'
command, but it is not possible to push a NHG that has not
allow-recursion flag set.

> sharp install routes 9.9.9.20 ... no-recurse
> => pushed
> nexthop-group A
>  nexthop 172.31.0.200
> => not pushed

This is a design issue related to the SHARP daemon only.
Change the design:
- Extend the nexthop group hooks with a running-config call back
- Add a vty command in SHARP only, under the nexthop-group node,
that will permit to push any NHG.

> nexthop-group A
>  force-nexthop-config
>  nexthop 172.31.0.200
>

The nhg will be sent to ZEBRA, and will be attempted to be
resolved.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  5. lib, zebra, doc: extend ibgp support to nhg in zebra 

    When routes from eBGP peers are pushed in ZEBRA, and are not
resolved over connected paths, an error message is displayed.
This is because neither the ALLOW_RECURSION, nor the IBGP flag
are set on the route. When attempting to do the same in SHARP,
it appears that the NHG do not have this IBGP flag.

> cli# debug zebra rib detail
> [..]
> 2023/12/17 21:09:43 ZEBRA: [NWWQT-S584X]         nexthop_active: Route Type bgp has not turned on recursion 172.31.0.102/32 failed to match
> 2023/12/17 21:09:43 ZEBRA: [PKF9S-7G8XM]         EBGP: see "disable-ebgp-connected-route-check" or "disable-connected-check"

Attempting to push NHGs to ZEBRA does not lead to the same
error messages, for two reasons:
- NHGs are not sent by SHARPD if allow-recursion flag is not set
- the IBGP flag is not implemented in NHGs

This commit includes two changes:
- introduce the ZEBRA_NHG_FLAG in the nexthop_group structure
The flag will be used by ZEBRA when attempting to check if
the nexthops of the NHG are active or not.
- add a vty command in nexthop group that maps over the IBGP
flag.

> ubuntu2204(config)# nexthop-group H
> ubuntu2204(config-nh-group)# ibgp

The below test shows that when turning on ibgp, the EBGP trace
disappears:

> ubuntu2204(config)# debu zebra nexthop de
> ubuntu2204(config)# debu zebra rib de
> ubuntu2204(config)# ip route 172.31.0.102/32 192.168.0.77
> ubuntu2204(config)# nexthop-group H
> ubuntu2204(config-nh-group)# force-nexthop-config
> ubuntu2204(config-nh-group)# nexthop 172.31.0.102
> [..]
> 2023/12/17 22:09:43 ZEBRA: [NWWQT-S584X]         nexthop_active: Route Type sharp has not turned on recursion 172.31.0.102/32 failed to match
> 2023/12/17 22:09:43 ZEBRA: [PKF9S-7G8XM]         EBGP: see "disable-ebgp-connected-route-check" or "disable-connected-check"
> ubuntu2204(config-nh-group)# ibgp
> 2023/12/17 22:14:57 ZEBRA: [NWWQT-S584X]         nexthop_active: Route Type sharp has not turned on recursion 172.31.0.102/32 failed to match

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  6. lib: fix copy srte_color from zapi_nexthop structure 

    When passing from nexthop to zapi_nexthop, the srte color
is copied. Do the same reversely.

Fixes: 31f937f ("lib, zebra: Add SR-TE policy infrastructure to zebra")

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  7. *: add srte color support in nhg 

    The nexthop group CLI can not configure color support.
Add a new option under nexthop command to configure an
srte color:

> nexthop-group 1
> [..]
>  nexthop 192.0.2.100 color 100

Add srte color support for nhg:
- Add NEXTHOP_GROUP_MESSAGE_COLOR support in NHG.
- Add ZAPI_NEXTHOP_MESSAGE_SRTE support in ZAPI.
- When checking for nexthop active, an SRTE policy with
the (color, nexthop ip) tuple will be looked ip.

Add a NHG sharp test for SRTE color:
- a NHG matching an SRTE policy is configured
- NHG sharp is extended to watch a given NHT color
> sharp watch nexthop 172.31.0.200 color 1
- Upon NHT call back, the NHG is re-added, and updates
the nexthop.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  8. zebra, lib, doc: add protocol-controlled command to nhg 

    Today, when a protocol creates a NHG, then ZEBRA automatically creates
a NHG dependency with this NHG. Creating dynamic NHGs at ZEBRA layer
goes against the concept of a protocol daemon that wants to entirely
control its NHG.
The below example considers the sharpd created nexthop as a NHG
with id 179687502, while the nexthop information is stored in a zebra
created nexthop 6462.

> ubuntu2204(config)# nexthop-group 10
> 2023/11/23 10:27:34 SHARP: [Q5NBA-GN1BG] NHG ID assigned: 179687502
> ubuntu2204(config-nh-group)# nexthop 192.0.2.200 loop10
> [..]
> ID: 179687502 (sharp)
>    RefCnt: 1
>    Uptime: 00:00:17
>    VRF: default
>    Valid, Installed
>    Depends: (6462)
>          via 192.0.2.200, loop1 (vrf default), weight 1
> ID: 6462 (sharp)
>     RefCnt: 2
>     Uptime: 00:00:17
>     VRF: default
>     Valid, Installed
>     Interface Index: 2964
>           via 192.0.2.200, loop1 (vrf default), weight 1
>     Dependents: (179687502)
>
> # ip nexthop ls
> [..]
> id 179687502 group 6462 proto 194
> id 6462 via 192.0.2.200 dev loop1 scope link proto 194

Add a CLI option to NHG that request zebra to not move the nexthop
information in a separate NHG.

> ubuntu2204(config-nh-group)# protocol-controlled
> ubuntu2204(config-nh-group)# nexthop 192.0.2.200 loop10
> ubuntu2204(config-nh-group)# do show nexthop-group rib sharpd
> ID: 179687504 (sharp)
>     RefCnt: 1
>     Uptime: 00:00:04
>     VRF: default
>     Valid, Installed
>           via 192.0.2.200, loop1 (vrf default), weight 1
>
> # ip nexthop ls
> [..]
> id 179687504 via 192.0.2.200 dev loop1 scope link proto 194

Add associate tests for that in topotests.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  9. *: move [backup_]nexthop from zapi_nhg into nhg_nexthop sub-structure 

    The zapi nexthop group structure is unable to reference other
nexthop groups. Actually, only nexthop IP addresses can be
associated to a nexthop group via the ZAPI interface.

This first commit is a preliminary commit that prepares the
ZAPI interface in order to host a second type of nexthop group,
by moving the current zapi_nexthop definition into a specific
sub-structure. This commit does not change the functionality.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  10. *: add nexthop_group group ids support, part 1 

    Today, protocol daemons can not create ECMP next-hops by using
multiple NHGs. The below configuration shows an ECMP NHG.

> nexthop-group ABCD
> nexthop 192.168.0.100 loop1
> nexthop 192.168.0.105 loop1
>

In the 'multiple NHG' case, 2 NHGs would be used for each
nexthop, and the 3rd ony would group the two first, similar
to what is done with iproute2:

> ip nexthop add id 210 via 192.168.0.100 dev loop1
> ip nexthop add id 211 via 192.168.0.105 dev loop1
> ip nexthop add id 212 group 210/211

Extend the nexthop group structure to support a list of nexthop
groups. Expose a vty API inside the nexthop group node, to
host a new command to configure a group name. That group
name points to another nexthop group.

> nexthop-group ABCD
> group ECMP1
> group ECMP2
> exit
> nexthop-group ECMP1
> nexthop 192.168.0.100 loop1
> exit
> nexthop-group ECMP2
> nexthop 192.168.0.105 loop1
> exit

This commit only focuses to changes in the ZAPI interface, and on
the sharpd daemon. The handling of group ids on zebra is stopped
in 'zebra_nhg_proto_add()' function.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  11. zebra: factorise 'show nexthop-group rib' nexthops 

    Reduce the code size by reusing the same code to display
nexthops and backup nexthops.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  12. zebra: move early rib_evpn_route_[add/delete]() function in early_ fu… 

    …nction

Move the rib_evpn_route_add() and rib_evpn_route_delete() functions
in a separate place.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  13. zebra: move route_entry_dump_nh() into route_entry_dump_nhg() 

    Factorise the nexthop display handling in a separate function.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  14. lib, zebra: add nhg group ids support, part 2, add nhg ref 

    When a nexthop group with dependencies is attached to a route entry,
the real nexthop flags are not easily reachable for read or write
operations.

In order to do so, at the route install, or at the nexthop group
update, for each nexthop dependency, use an internal nhg pointer to
remember the used nexthop group. The pointer is refreshed at nexthop
group replacement.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  15. zebra: add nexthop group ids support, part 3 

    The zebra nexthop group support is not adapted to create
dependencies between group when a request comes from the
routing protocols.

Add those extra changes in the zebra nexthop group library
for that, a stub is temporarily added in dataplane_ctx_init.

The changes ignore for now the zebra dataplane handling.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  16. zebra: add nexthop group ids support, part 4, netlink 

    Add support to install routes attached to a nexthop group
which is dependent of other nexthop groups:
- Disable the src option.
- The dataplane stub is removed

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  17. zebra: rework show_nexthop_group_out_nexthop() separate function 

    Create a separate function to handle separately the nexthop structure.
On the next commit, when a nexthop group is used, the nexthop of
each nexthop group dependency is used.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  18. zebra: rework 'vty_show_ip_route()' function 

    The show_route_nexthop_group_helper() and the
show_nexthop_group_json_helper() helper functions are introduced
to separate nexthop handling from the remaining 'show ip route'
command.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  19. zebra: add nexthop group ids support, part 5, show 

    The following commands can not be used when using nhg groups,
forged by the protocol:
- 'show nexthop-group rib'
- 'show ip route'

Add the support for the 2 commands

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  20. zebra: rework no nexthop available test 

    Some tests may check if there is a valid nexthop in a
nexthop-group. Generalize the check by accounting for the
number of nexthops in a nexthop group.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  21. zebra: rework mpls uninstall based on nexthop group 

    Create a mpls_ftn_uninstall_nhg() function that handles the
nexthop parsing for each route entry. This parsing is common
to primary and backup nexthops.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  22. zebra: add support for 'mpls uninstall' of nexthop group dependencies 

    The nexthop group dependencies may also have an NHLFE entry.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  23. zebra: rework zsend_redistribute_route() function with nhg 

    Create a second function zsend_redistribute_route_nhg() to
handle nexthop group.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  24. zebra: add support for redistributed routes with nexthop groups 

    Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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  25. topotests: all_protocol_startup, add nexthop-group test with nhg group 

    An ECMP configuration is tested with nexthop group.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
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