[j-nsp] hidden route

[Tomasz Opala]

Hi gurus,

Imagine following topology:

P2(AS11)------R2(AS100)-------R3(AS100)-------P3(AS11)

In order to advertise route 199.199.0.0/16 (static, redistriuted to BGP)
from router P2 to P3 (and some routes form P3 to P2), as-override has been
configured on both R2 and R3:

write at R2# show group p2
type external;
peer-as 11;
as-override;
neighbor 192.168.1.2;

[edit protocols bgp]
write at R2#

write at R3# show group p3
type external;
peer-as 11;
as-override;
neighbor 192.168.2.2;

{master}[edit protocols bgp]
write at R3#


Route 199.199.0.0/16 is present in P3 routing table:

p3 at P3> show route protocol bgp terse 199.199/16

inet.0: 5 destinations, 5 routes (5 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

A Destination        P Prf   Metric 1   Metric 2  Next hop        AS path
* 199.199.0.0/16     B 170        100            >192.168.2.1     100 100 I


Apparently the same route is advertised back, from R2 to P2 (it can be seen
as a hidden route):

p2 at P2> show route hidden extensive

inet.0: 8 destinations, 10 routes (8 active, 0 holddown, 1 hidden)
199.199.0.0/16 (2 entries, 1 announced)
TSI:
KRT in-kernel 199.199.0.0/16 -> {}
Page 0 idx 0 Type 1 val 89768b8
    Nexthop: Self
    AS path: [11] I
    Communities:
Path 199.199.0.0 Vector len 4.  Val: 0
         BGP
                Next hop type: Router
                Next-hop reference count: 1
                Source: 192.168.1.1
                Next hop: 192.168.1.2 via ge-1/2/1.2, selected
                State: <Hidden Ext>
                Inactive reason: Unusable path
                Local AS:    11 Peer AS:   100
                Age: 13:52:22
                Task: BGP_100.192.168.1.1+60006
                AS path: 100 100 I
                Router ID: 10.0.1.2

p2 at P2>


Do you have any explanation of hidden route in P2?

Thanks,
Tomasz