[j-nsp] Interpreting output of "show route route protocol bgpdetail"

[Nalkhande Tarique Abbas]

Junaid,

It's the Preference2 value.
JUNOS stores the 1's complement of the LocalPref value in the
Preference2 field. For example, if the LocalPref value for Route 1 is
100, the Preference2 value is -101. If the LocalPref value for Route 2
is 155, the Preference2 value is -156. Route 2 is preferred because it
has a higher LocalPref value and simultaneously a lower Preference2
value.

Nothing to worry, its just done to use a common comparison routine
(Since in every routing metric except for the BGP LocalPref attribute, a
lesser value is preferred)

Hope it clarifies.

 
BR//
Tarique


-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net
[mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Junaid
Sent: Saturday, June 13, 2009 4:21 PM
To: Juniper-Nsp
Subject: [j-nsp] Interpreting output of "show route route protocol
bgpdetail"

Hi, there is something that's bothering me for quite a while; can anyone
please explain what does "-101" signify in the following output in the
"Preference" field:

# run show route protocol bgp detail

inet.0: 20 destinations, 20 routes (20 active, 0 holddown, 0 hidden)
192.168.20.0/24 (1 entry, 1 announced)
        *BGP    Preference: 170/-101
                Next hop type: Indirect
                Next-hop reference count: 3
                Source: 10.0.4.13
                Next hop type: Router, Next hop index: 131071
                Next hop: 10.0.4.6 via em3.12
                Next hop: 10.0.4.13 via em3.13, selected
                Protocol next hop: 10.0.4.2
                Indirect next hop: 8a2209c 131072
                State: <Active Int Ext>
                Local AS: 65412 Peer AS: 65412
                Age: 3:48       Metric2: 10
                Task: BGP_65412.10.0.4.13+179
                Announcement bits (2): 0-KRT 5-Resolve tree 2
                AS path: I (Originator) Cluster list:  1.1.1.1
                AS path:  Originator ID: 10.0.6.2
                Localpref: 100
                Router ID: 10.0.3.3


Thank you.

-- 

Regards,
Junaid
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