![]() Disallow the resolution to nexthops that are marked duplicate. When we are resolving to an ecmp group, it's possible this group has duplicates. I found this when I hit a bug where we can have groups resolving to each other and cause the resolved->next->next pointer to increase exponentially. Sufficiently large ecmp and zebra will grind to a hault. Like so: ``` D> 4.4.4.14/32 [150/0] via 1.1.1.1 (recursive), weight 1, 00:00:02 * via 1.1.1.1, dummy1 onlink, weight 1, 00:00:02 via 4.4.4.1 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.2 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.3 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.4 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.5 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.6 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.7 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.8 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.9 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.10 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.11 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.12 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.13 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.15 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1 onlink, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1 onlink, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 4.4.4.16 (recursive), weight 1, 00:00:02 via 1.1.1.1, dummy1 onlink, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 via 1.1.1.1, dummy1, weight 1, 00:00:02 D> 4.4.4.15/32 [150/0] via 1.1.1.1 (recursive), weight 1, 00:00:09 * via 1.1.1.1, dummy1 onlink, weight 1, 00:00:09 via 4.4.4.1 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.2 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.3 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.4 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.5 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.6 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.7 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.8 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.9 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.10 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.11 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.12 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.13 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.14 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 4.4.4.16 (recursive), weight 1, 00:00:09 via 1.1.1.1, dummy1 onlink, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 via 1.1.1.1, dummy1, weight 1, 00:00:09 D> 4.4.4.16/32 [150/0] via 1.1.1.1 (recursive), weight 1, 00:00:19 * via 1.1.1.1, dummy1 onlink, weight 1, 00:00:19 via 4.4.4.1 (recursive), weight 1, 00:00:19 via 1.1.1.1, dummy1, weight 1, 00:00:19 via 4.4.4.2 (recursive), weight 1, 00:00:19 ............... ................ and on... ``` You can repro the above via: ``` kernel routes: 1.1.1.1 dev dummy1 scope link 4.4.4.0/24 via 1.1.1.1 dev dummy1 ============================== config: nexthop-group doof nexthop 1.1.1.1 nexthop 4.4.4.1 nexthop 4.4.4.10 nexthop 4.4.4.11 nexthop 4.4.4.12 nexthop 4.4.4.13 nexthop 4.4.4.14 nexthop 4.4.4.15 nexthop 4.4.4.16 nexthop 4.4.4.2 nexthop 4.4.4.3 nexthop 4.4.4.4 nexthop 4.4.4.5 nexthop 4.4.4.6 nexthop 4.4.4.7 nexthop 4.4.4.8 nexthop 4.4.4.9 ! =========================== Then use sharpd to install 4.4.4.16 -> 4.4.4.1 pointing to that nexthop group in decending order. ``` With these changes it prevents the growing ecmp above by disallowing duplicates to be in the resolution decision. These nexthops are not installed anyways so why should we be resolving to them? Signed-off-by: Stephen Worley <sworley@nvidia.com> |
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FRRouting
FRR is free software that implements and manages various IPv4 and IPv6 routing protocols. It runs on nearly all distributions of Linux and BSD and supports all modern CPU architectures.
FRR currently supports the following protocols:
- BGP
- OSPFv2
- OSPFv3
- RIPv1
- RIPv2
- RIPng
- IS-IS
- PIM-SM/MSDP
- LDP
- BFD
- Babel
- PBR
- OpenFabric
- VRRP
- EIGRP (alpha)
- NHRP (alpha)
Installation & Use
For source tarballs, see the releases page.
For Debian and its derivatives, use the APT repository at https://deb.frrouting.org/.
Instructions on building and installing from source for supported platforms may be found in the developer docs.
Once installed, please refer to the user guide for instructions on use.
Community
The FRRouting email list server is located here and offers the following public lists:
Topic | List |
---|---|
Development | dev@lists.frrouting.org |
Users & Operators | frog@lists.frrouting.org |
Announcements | announce@lists.frrouting.org |
For chat, we currently use Slack. You can join by clicking the "Slack" link under the Participate section of our website.
Contributing
FRR maintains developer's documentation which contains the project workflow and expectations for contributors. Some technical documentation on project internals is also available.
We welcome and appreciate all contributions, no matter how small!
Security
To report security issues, please use our security mailing list:
security [at] lists.frrouting.org