bgpd does not re-route correctly when I shut down a transit when I
use a bgp-only design, causing black-holes for some prefixes.
router-01 and router-02 are in the same AS and peer with the same transit
provider.
router-01 and router-02 have two ibgp peerings, primary and standby path.
router-01 sets localpref 60 on all transit prefixes, router-02 sets
local-pref 50.
When I take down the transit on router-01 I see this on router-02:
router-02# bgpctl show rib | head -n 10
flags: * = Valid, > = Selected, I = via IBGP, A = Announced
origin: i = IGP, e = EGP, ? = Incomplete
flags destination gateway lpref med aspath origin
I*> 26.0.128.0/17 172.17.1.1 60 11100 65100 i
* 26.0.128.0/17 192.168.100.5 50 10100 65100 i
I*> 26.0.144.0/22 172.17.1.1 60 11100 65100 i
* 26.0.144.0/22 192.168.100.5 50 10100 65100 i
I*> 26.1.77.0/24 172.17.1.1 60 11100 65100 i
* 26.1.77.0/24 192.168.100.5 50 10100 65100 i
router-02#
prefixes with local-pref 60 pointing at router-01.
router-01 does not have it's transit peering up, and thus itself has no
prefixes with local-pref 60.
router-01# bgpctl show rib | head -n
10
flags: * = Valid, > = Selected, I = via IBGP, A = Announced
origin: i = IGP, e = EGP, ? = Incomplete
flags destination gateway lpref med aspath origin
I*> 26.0.128.0/17 172.17.1.6 50 21100 65100 i
I*> 26.0.144.0/22 172.17.1.6 50 21100 65100 i
I*> 26.1.77.0/24 172.17.1.6 50 21100 65100 i
I*> 26.2.172.0/22 172.17.1.6 50 21100 65100 i
I*> 26.3.241.0/24 172.17.1.6 50 21100 65100 i
I*> 26.6.126.0/24 172.17.1.6 50 21100 65100 i
router-01# bgpctl show rib 26.0.128.0/17 all
flags: * = Valid, > = Selected, I = via IBGP, A = Announced
origin: i = IGP, e = EGP, ? = Incomplete
flags destination gateway lpref med aspath origin
I*> 26.0.128.0/17 172.17.1.6 50 21100 65100 i
I*> 26.0.144.0/22 172.17.1.6 50 21100 65100 i
router-01#
I saw this before when I tested bgpd around a year ago. So it isn't a new
bug.
This is with 4.2-RELEASE, no patches.
This info is from a lab I setup to replicate a live environment.
/Tony
router-01# cat /etc/bgpd.conf
# $OpenBSD: bgpd.conf,v 1.8 2007/03/29 13:37:35 claudio Exp $
# sample bgpd configuration file
# see bgpd.conf(5)
#macros
loopback="172.17.0.1"
# global configuration
AS 65200
router-id $loopback
network $loopback/32 set {localpref 120, med 10}
network 172.17.0.0/16 set {localpref 120, med 10}
network connected set {localpref 120, med 10}
network static set {localpref 120, med 10}
group "TRANSIT" {
remote-as 65100
announce all
set nexthop self
set med 10100
set localpref 60
neighbor 192.168.100.1 {
descr "TRANSIT"
}
}
group "IBGP" {
remote-as 65200
route-reflector
set nexthop self
set med +1000
neighbor 172.17.1.2 {
local-address 172.17.1.1
descr "router-02 primary"
}
neighbor 172.17.1.6 {
local-address 172.17.1.5
descr "router-02 standby"
set med +10000
}
}
# filter
deny from any
deny to any
allow quick to group "IBGP"
allow quick from group "IBGP"
allow quick to group "TRANSIT" prefix 172.17.0.0/16
allow quick from group "TRANSIT"
router-01#
ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33208
groups: lo
inet 127.0.0.1 netmask 0xff000000
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x5
ne3: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 52:54:00:12:02:01
description: transit
media: Ethernet 10baseT full-duplex
inet6 fe80::5054:ff:fe12:201%ne3 prefixlen 64 scopeid 0x1
inet 192.168.100.2 netmask 0xfffffffc broadcast 192.168.100.3
ne4: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 52:54:00:12:02:02
description: router-01 primary path
media: Ethernet 10baseT full-duplex
inet6 fe80::5054:ff:fe12:202%ne4 prefixlen 64 scopeid 0x2
inet 172.17.1.1 netmask 0xfffffffc broadcast 172.17.1.3
ne5: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 52:54:00:12:02:03
description: route-02 standby path
media: Ethernet 10baseT full-duplex
inet6 fe80::5054:ff:fe12:203%ne5 prefixlen 64 scopeid 0x3
inet 172.17.1.5 netmask 0xfffffffc broadcast 172.17.1.7
enc0: flags=0<> mtu 1536
lo1: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33208
description: ROUTING LOOPBACK
groups: lo
inet 172.17.0.1 netmask 0xffffffff
router-01#
router-02# cat /etc/bgpd.conf
# $OpenBSD: bgpd.conf,v 1.8 2007/03/29 13:37:35 claudio Exp $
# sample bgpd configuration file
# see bgpd.conf(5)
#macros
loopback="172.17.0.2"
# global configuration
AS 65200
router-id $loopback
network $loopback/32 set {localpref 120, med 10}
network 172.17.0.0/16 set {localpref 120, med 10}
network connected set {localpref 120, med 10}
network static set {localpref 120, med 10}
group "TRANSIT" {
remote-as 65100
announce all
set nexthop self
set med 10100
set localpref 50
neighbor 192.168.100.5 {
descr "TRANSIT"
}
}
group "IBGP" {
remote-as 65200
route-reflector
set nexthop self
set med +1000
neighbor 172.17.1.1 {
local-address 172.17.1.2
descr "router-01 primary"
}
neighbor 172.17.1.5 {
local-address 172.17.1.6
descr "router-01 standby"
set med +10000
}
}
# filter
deny from any
deny to any
allow quick to group "IBGP"
allow quick from group "IBGP"
allow quick to group "TRANSIT" prefix 172.17.0.0/16
allow quick from group "TRANSIT"
router-02#
ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33208
groups: lo
inet 127.0.0.1 netmask 0xff000000
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x5
ne3: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 52:54:00:12:03:01
description: transit
media: Ethernet 10baseT full-duplex
inet6 fe80::5054:ff:fe12:301%ne3 prefixlen 64 scopeid 0x1
inet 192.168.100.6 netmask 0xfffffffc broadcast 192.168.100.7
ne4: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 52:54:00:12:03:02
description: router-02 primary path
media: Ethernet 10baseT full-duplex
inet6 fe80::5054:ff:fe12:302%ne4 prefixlen 64 scopeid 0x2
inet 172.17.1.2 netmask 0xfffffffc broadcast 172.17.1.3
ne5: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 52:54:00:12:03:03
description: router-02 standby path
media: Ethernet 10baseT full-duplex
inet6 fe80::5054:ff:fe12:303%ne5 prefixlen 64 scopeid 0x3
inet 172.17.1.6 netmask 0xfffffffc broadcast 172.17.1.7
enc0: flags=0<> mtu 1536
lo1: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33208
groups: lo
inet 172.17.0.2 netmask 0xffffffff
router-02#
