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

[Aaron Gould]

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