duplicate device routes on linux
ico
ico at petrzalka.net
Mon Feb 20 14:47:39 CET 2023
Hello all,
Here at $work we are using bird for OSPF at some 30 linux boxes. Works
great. But there is a thing that confuses me:
Let's have some simple linux box:
# ip addr
1: lo: ...rest of loopback output
2: eth0 at if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
state UP group default qlen 1000
link/ether 86:37:65:15:fa:d9 brd ff:ff:ff:ff:ff:ff link-netns r2
inet 10.0.0.1/24 scope global eth0
valid_lft forever preferred_lft forever
# ip route
10.0.0.0/24 dev eth0 proto kernel scope link src 10.0.0.1
As you can see, there is single interface with single address, single
device route automatically generated by kernel. Simple bird config:
# cat bird.conf
# BEGIN bird config
router id 10.0.0.1;
protocol device {
scan time 3;
}
protocol kernel krnl4 {
ipv4 {
table master4;
import all; export all;
};
learn;
}
protocol ospf ospf1 {
ipv4 {
table master4;
import all; export all;
};
area 0.0.0.0 {
stub no;
interface "eth0" {
stub yes;
};
};
}
# END bird config
When I run bird with this configuration, it inserts another route:
# ip route
10.0.0.0/24 dev eth0 proto kernel scope link src 10.0.0.1
10.0.0.0/24 dev eth0 proto bird scope link metric 32
Is this expected/correct behaviour? Or should I somehow filter those
device routes out? I want those device routes to be read by OSPF, of
course, just not to output them back. What is the best way to get rid of
them?
Another unrelated question: When I run bird, it logs this:
bird: KRT: Netlink strict checking failed, will scan all tables at once
bird: Started
Should I do something about that failed strict check? Is it important or
only some info message I shouldn't worry about?
Thank you
ico
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