Introduce scalable route multipath.

This change is based on the nexthop objects landed in D24232.

The change introduces the concept of nexthop groups.
Each group contains the collection of nexthops with their
relative weights and a dataplane-optimized structure to enable
efficient nexthop selection.

Simular to the nexthops, nexthop groups are immutable. Dataplane part
gets compiled during group creation and is basically an array of
nexthop pointers, compiled w.r.t their weights.

With this change, `rt_nhop` field of `struct rtentry` contains either
nexthop or nexthop group. They are distinguished by the presense of
NHF_MULTIPATH flag.
All dataplane lookup functions returns pointer to the nexthop object,
leaving nexhop groups details inside routing subsystem.

User-visible changes:

The change is intended to be backward-compatible: all non-mpath operations
should work as before with ROUTE_MPATH and net.route.multipath=1.

All routes now comes with weight, default weight is 1, maximum is 2^24-1.

Current maximum multipath group width is statically set to 64.
This will become sysctl-tunable in the followup changes.

Using functionality:
* Recompile kernel with ROUTE_MPATH
* set net.route.multipath to 1

route add -6 2001:db8::/32 2001:db8::2 -weight 10
route add -6 2001:db8::/32 2001:db8::3 -weight 20

netstat -6On

Nexthop groups data

Internet6:
GrpIdx NhIdx Weight Slots Gateway Netif Refcnt
1 ------- ------- ------- --------------------------------------- --------- 1
13 10 1 2001:db8::2 vlan2
14 20 2 2001:db8::3 vlan2

Next steps:
* Land outbound hashing for locally-originated routes ( D26523 ).
* Fix net/bird multipath (net/frr seems to work fine)
* Add ROUTE_MPATH to GENERIC
* Set net.route.multipath=1 by default

Tested by: olivier
Reviewed by: glebius
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D26449

This commit is contained in:

Alexander V. Chernikov

2020-10-03 10:47:17 +00:00

committed by

Sebastian Huber

parent 9dd91a8330

commit 48ba673ce9

1 changed files with 1 additions and 0 deletions

									
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newlib/libc/sys/rtems/include/sys/socket.h

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				@ -409,6 +409,7 @@ struct sockproto {

				#define	NET_RT_IFLISTL	5		/* Survey interface list, using 'l'en

									 * versions of msghdr structs. */

				#define NET_RT_NHOP	6		/* dump routing nexthops */

				#define NET_RT_NHGRP	7		/* dump routing nexthop groups */

				#endif /* __BSD_VISIBLE */

				/*

Introduce scalable route multipath.

1 newlib/libc/sys/rtems/include/sys/socket.h Unescape Escape View File

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newlib/libc/sys/rtems/include/sys/socket.h

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