[j-nsp] can i see bgp looped AS PATH prefixes on the receiving router

[Shamen Snyder]

I've only ever used the *loops* knob for hub and spoke VPNs. There may be
some other use cases, but I'm not aware of them.


On Fri, Jun 16, 2017 at 9:34 PM, Aaron Gould <aaron1 at gvtc.com> wrote:

> Here’s what happened when I added “loops 1”  …it seemed to just allow
> those previously loop-detected prefixes, to now be allowed into the rib.
> True ?  is this safe ?  I mean isn’t this what AS PATH loop detection is
> supposed to prevent.  Then again, maybe if you know a good reason to do
> this, then I guess you just have to be careful and know what you’re going
> huh
>
>
>
> ****** before…
>
>
>
> [edit]
>
> r4 at lab-mx104:r4# run show route receive-protocol bgp 10.0.2.9
>
>
>
> inet.0: 35 destinations, 39 routes (35 active, 0 holddown, 0 hidden)
>
>   Prefix                  Nexthop              MED     Lclpref    AS path
>
> * 192.168.50.0/24         10.0.2.9                     100        (65001)
> I
>
>   192.168.60.0/24         10.0.9.6                     100        (65001)
> I
>
>   192.168.70.0/24         10.0.9.7                     100        (65001)
> I
>
>
>
> ...looking at one of them...
>
>
>
> [edit]
>
> r4 at lab-mx104:r4# run show route protocol bgp 192.168.10.0
>
>
>
> inet.0: 35 destinations, 39 routes (35 active, 0 holddown, 0 hidden)
>
> + = Active Route, - = Last Active, * = Both
>
>
>
> 192.168.10.0/24    *[BGP/170] 08:07:39, localpref 101, from 10.0.6.1
>
>                       AS path: I, validation-state: unverified
>
>                     > to 10.0.4.10 via lt-0/1/0.42
>
>
>
> ****** after…
>
>
>
> [edit]
>
> r4 at lab-mx104:r4# set protocols bgp group my-cbgp family inet unicast
> loops 1
>
>
>
> [edit]
>
> r4 at lab-mx104:r4# run show route receive-protocol bgp 10.0.2.9
>
>
>
> inet.0: 35 destinations, 43 routes (35 active, 0 holddown, 0 hidden)
>
>   Prefix                  Nexthop              MED     Lclpref    AS path
>
> * 192.168.10.0/24         10.0.6.1                     101        (65001
> 65000) I
>
> * 192.168.20.0/24         10.0.6.2                     100        (65001
> 65000) I
>
>   192.168.30.0/24         10.0.2.2                     100        (65001
> 65000) I
>
> * 192.168.50.0/24         10.0.2.9                     100        (65001)
> I
>
>   192.168.60.0/24         10.0.9.6                     100        (65001)
> I
>
>   192.168.70.0/24         10.0.9.7                     100        (65001)
> I
>
> * 192.168.100.0/24        10.0.6.1                     101        (65001
> 65000) I
>
>
>
> ...looking at one of them...
>
>
>
> [edit]
>
> r4 at lab-mx104:r4# run show route protocol bgp 192.168.10.0
>
>
>
> inet.0: 35 destinations, 43 routes (35 active, 0 holddown, 0 hidden)
>
> + = Active Route, - = Last Active, * = Both
>
>
>
> 192.168.10.0/24    *[BGP/170] 00:00:13, localpref 101, from 10.0.2.9
>
>                       AS path: (65001 65000) I, validation-state:
> unverified
>
>                     > to 10.0.4.10 via lt-0/1/0.42
>
>                     [BGP/170] 08:08:35, localpref 101, from 10.0.6.1
>
>                       AS path: I, validation-state: unverified
>
>                     > to 10.0.4.10 via lt-0/1/0.42
>
>
>
>
>
> - Aaron Gould
>