Date: Mon, 30 Jul 2018 16:29:23 +0200 From: Tobias Urdin <tobias.urdin@binero.se> To: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: ospf redistribute into openbgpd overwrites directly connected routes Message-ID: <ad38f335-51e9-7b98-56b7-29058f126398@binero.se> In-Reply-To: <9507d752-6815-92fe-924b-55459710bb9d@binero.se> References: <9507d752-6815-92fe-924b-55459710bb9d@binero.se>
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Should note that I can resolve this by filtering the incoming prefixes with:
deny from group "peering ASxxxx" prefix 172.20.104.0/22 prefixlen = 22
Which I'm doing right now to workaround the problem and being able to
continue
working but I don't understand why openbgpd would overwrite directly
connected routes.
If somebody could clear that up for me I would be super grateful :)
Best regards
Tobias
On 07/30/2018 04:09 PM, Tobias Urdin wrote:
> Hello,
>
> I have a setup where we connect a OSPF area with a edge router, this
> edge router then has a BGP peer to my router
> where it redistributes all OSPF routes into the BGP feed to my router.
>
> My router is running FreeBSD 11.1 with openbgpd
>
> root@myrouter:~ # uname -a
> FreeBSD dr20-1-sto1 11.1-RELEASE FreeBSD 11.1-RELEASE #0 r321309: Fri
> Jul 21 02:08:28 UTC 2017
> root@releng2.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC amd64
>
> root@myrouter:~ # pkg info openbgpd
> openbgpd-5.2.20121209_2
> Name : openbgpd
> Version : 5.2.20121209_2
>
> The thing here is that my router has layer 2 access directly to one of
> the networks that the edge router BGP announces to my router
> (172.20.104.0/22).
> When my FreeBSD machine boots it will install a directly connected route
> for 172.20.104.0/22 in my routing table but as soon as openbgpd starts
> it will
> install a 172.20.104.0/22 route with the nexthop of the edge router instead.
>
> How can I prevent openbgpd from overwriting the directly connected route?
> Directly connected networks should never be overwritten by a routing
> protocol but I suspect this is because of the redistribute.
>
> I've tried messing with metrics, but maybe I to create a rtable and mess
> around with that?
> Output of some info is below.
>
> Best regards
> Tobias
>
> root@myrouter:~ # bgpctl show fib connected | grep 104
> *C 48 172.20.104.0/22 link#10
>
> root@myrouter:~ # route get 172.20.104.100
> route to: 172.20.104.100
> destination: 172.20.104.0
> mask: 255.255.252.0
> gateway: edgerouter
> fib: 0
> interface: vlan10
> flags: <UP,GATEWAY,DONE,PROTO1,PINNED>
> recvpipe sendpipe ssthresh rtt,msec mtu weight expire
> 0 0 0 0 1500 1 0
>
> root@myrouter:~ # ifconfig vlan10
> vlan10: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST>
> metric 0 mtu 1500
> options=600703<RXCSUM,TXCSUM,TSO4,TSO6,LRO,RXCSUM_IPV6,TXCSUM_IPV6>
> ether x
> inet 172.20.107.253 netmask 0xfffffc00 broadcast 172.20.107.255
> inet 172.20.107.254 netmask 0xfffffc00 broadcast 172.20.107.255
> vhid 2
> nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
> media: Ethernet autoselect (10Gbase-Twinax
> <full-duplex,rxpause,txpause>)
> status: active
> vlan: 10 vlanpcp: 0 parent interface: ix1
> carp: MASTER vhid 2 advbase 1 advskew 10
> groups: vlan
>
> root@myrouter:~ # cat /etc/rc.conf
> ...snip..
> ifconfig_vlan10="inet 172.20.107.253 netmask 255.255.252.0 vlan 10
> vlandev ix1"
> ifconfig_vlan10_alias0="inet vhid 2 advskew 100 pass test123 alias
> 172.20.107.254/22"
>
> root@myrouter:~ # cat /usr/local/etc/bgpd.conf
> ...snip...
> group "peering ASxxxx" {
> remote-as xxxx
> softreconfig in yes
>
> neighbor edgerouter {
> announce self
> descr "AS xxxx edgerouter"
> local-address xxxx
> depend on <outside int>
> }
> }
> ...snip...
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