running two bird daemons which listen on loopback IP

[Pavlos Parissis]

On 19/06/2018 06:19 μμ, Ondrej Zajicek wrote:
> On Tue, Jun 19, 2018 at 05:34:06PM +0200, Pavlos Parissis wrote:
>> Hi,
>>
>> For testing purposes I want to run two bird instances which listen on two different IPs. Those IP
>> addresses are assigned to loopback interface(Linux box). I have configured BGP but each daemon is
>> waiting the other to become neighbor.
>>
>> I run tcpdump on loopback interface and I don't see any network traffic, and I am wondering if
>> using loopback inteface isn't supported.
> 
> Hi
> 
> It is likely unrelated to loopback. There are two cases:
> 
> BGP is EBGP (direct mode) - in this case BIRD checks if the destination
> IP address is a direct neighbor and a local address is not considered
> direct neighbor, so there is 'waiting to become neighbor' issue.
> 
> BGP is IBGP (multihop mode) - in this case it is regular TCP connection
> and two local BIRD instances on two different local IPs work just fine.
> 
> You can switch to IBGP (same AS numbers) or just force multihop for
> EBGP mode ('multihop' option).
> 

That was the missing option to get it working. I had "direct" and replace it with "multihop". I also
had to set "listen bgp address <IP1>" in order to not listen to all IPs as a single instance running
was gaving me errors:
BGP: Unexpected connect from unknown address 10.52.12.1 (port 46089)

Here is my compete config where 10.52.12.0/24 are assigned to loopback interface

cat bird-server.conf
log syslog { debug, trace, info, remote, warning, error, auth, fatal, bug };
timeformat protocol "%F %T %s";
timeformat route "%F %T %s";

router id 10.52.12.1;
listen bgp address 10.52.12.1;

protocol device {
    scan time 10;
}

protocol static {
    disabled yes;
}

protocol direct direct1 {
    interface "lo";
        debug all;
        export none;
        import all;
}

protocol bgp BGP1 {
    disabled no;
    description "Peer-BGP1";
    neighbor 10.52.12.2 as 64815;
    source address 10.52.12.1;
    bfd off;
    debug all;
    #debug { states, routes, filters, interfaces, events };
    import none;
    export all;
    #direct;
    multihop;
    hold time 10;
    startup hold time 240;
    connect retry time 120;
    keepalive time 3;
    connect delay time 5;
    error wait time 10, 300;
    error forget time 300;
    disable after error off;
    next hop self;
    path metric 1;
    default bgp_med 0;
    default bgp_local_pref 0;
    local as 64815;
}


at bird-switch.conf
log syslog { debug, trace, info, remote, warning, error, auth, fatal, bug };
debug protocols all;
timeformat protocol "%F %T %s";
timeformat route "%F %T %s";

router id 10.52.12.2;
listen bgp address 10.52.12.2;

protocol device {
    disabled yes;
}

protocol static {
    disabled yes;
}

protocol direct direct1 {
    disabled yes;
}

protocol bgp BGP1SWITCH {
    disabled no;
    description "Switch-BGP1";
    neighbor 10.52.12.1 as 64815;
    source address 10.52.12.2;
    debug all;
    bfd off;
    debug { states, routes, filters, interfaces, events };
    import all;
    export none;
    multihop;
    hold time 10;
    startup hold time 240;
    connect retry time 120;
    keepalive time 3;
    connect delay time 5;
    error wait time 10, 300;
    error forget time 300;
    disable after error off;
    next hop self;
    path metric 1;
    default bgp_med 0;
    default bgp_local_pref 0;
    local as 64815;
}


Thanks a lot for your assistance, it is very much appreciated.

Cheers,
Pavlos

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