[j-nsp] Juniper BGP Route Metrics

Dan Benson dbenson at swingpad.com
Wed May 16 09:13:18 EDT 2007


Alan and all, I am currently tracking IGP metrics in LDP.  Please see my 
show route proto bgp detail below.  I have changed my router-id's just 
to stop and punks form trying to have fun with all the spare time they 
have..  Hope you understand.  Thanks again for the help.. //db

show route protocol bgp 155.212.0.0 detail (Random subnet learned from a 
peer AS):

inet.0: 217037 destinations, 706742 routes (217035 active, 2 holddown, 0 
hidden)
155.212.0.0/16 (3 entries, 1 announced)
       *BGP    Preference: 170/-91
               Next-hop reference count: 35478
               Source: 10.0.0.16
               Next hop: via at-0/0/0.0, selected
               Label operation: Push 198480
               Protocol next hop: 198.32.118.12
               Indirect next hop: 93403a8 262226
               State: <Active Int Ext>
               Local AS:  1784 Peer AS:  1784
               Age: 4d 14:15:14        Metric: 0       Metric2: 0
               Task: BGP_1784.10.0.0.16+2131
               Announcement bits (3): 0-KRT 5-RT 6-Resolve tree 2
               AS path: 174 14751 14751 14751 I ()
               Communities: 1784:1001
               Localpref: 90
               Router ID: 10.0.0.16
        BGP    Preference: 170/-91
               Next-hop reference count: 11931
               Source: 10.0.0.80
               Next hop: via at-0/0/0.0, selected
               Label operation: Push 198576
               Protocol next hop: 198.32.124.103
               Indirect next hop: 12734750 262165
               State: <Int Ext>
               Inactive reason: Router ID
               Local AS:  1784 Peer AS:  1784
               Age: 4d 14:15:31        Metric: 0       Metric2: 0
               Task: BGP_1784.10.0.0.80+179
               AS path: 174 14751 14751 14751 I ()
               Communities: 1784:1001
               Localpref: 90
               Router ID: 10.0.0.80
        BGP    Preference: 170/-91
               Next-hop reference count: 11682
               Source: 10.0.0.113
               Next hop: via at-0/0/0.0, selected
               Protocol next hop: 198.32.176.131
               Indirect next hop: 9340444 262289
               State: <Int Ext>
               Inactive reason: Router ID
               Local AS:  1784 Peer AS:  1784
               Age: 4d 14:14:59        Metric: 0       Metric2: 0
               Task: BGP_1784.10.0.0.113+3209
               AS path: 174 14751 14751 14751 I ()
               Communities: 1784:1001
               Localpref: 90
               Router ID: 10.0.0113

As you can see, I am not getting ANY metrics or metrics2 in my routes 
learned from internal peers.  I would like to see a metric that is 
directly associated with the IGP metric from the local router to the 
edge router's loopback but I am starting to think it my just be a pipe 
dream.   Thanks again.. //db

Alan Gravett wrote:
> Dan,
>  
> I suggest you double check whether the routers are configured as 
> suggested -
> [ edit protocols ldp ]
> track-igp-metric
>  
> If the route selection is based on BGP as you suggest and you are 
> running LDP everywhere then
> there should not be any change to the BGP next-hop selected, suspect 
> the tie-breaker is
> IGP metric. The default metric for LDP is 1, which is why you need to 
> "track-igp-metric".
>  
> Alan
>
>  
> On 5/16/07, *Dan Benson* <dbenson at swingpad.com 
> <mailto:dbenson at swingpad.com>> wrote:
>
>     Piotr, Thank you for the thought.  I am currently happy with the LDP
>     aspect of the network and yes I am tracking IGP for LDP learned
>     routes but
>     my issue is purely in BGP and how the routes go all the way down
>     the line
>     to the tie breaker of router-id.  Any others thoughts are
>     welcome.  Thanks
>     again.. //db
>
>     On Tue, May 15, 2007 5:00 pm, Piotr Marecki wrote:
>     > Hi Dan,
>     >
>     >
>     > Are you using LDP ? Try "track-igp-metric" under [protocols ldp]
>     stanza.
>     >
>     >
>     > regards
>     >
>     > Piotr Marecki
>     >
>     >
>     > ----- Original Message -----
>     > From: "Dan Benson" <dbenson at swingpad.com
>     <mailto:dbenson at swingpad.com>>
>     > To: <juniper-nsp at puck.nether.net
>     <mailto:juniper-nsp at puck.nether.net>>
>     > Sent: Tuesday, May 15, 2007 10:08 PM
>     > Subject: [j-nsp] Juniper BGP Route Metrics
>     >
>     >
>     >
>     >> All, I am in a funny spot in my network where I could you a little
>     >> assistance.  I run a fairly widespread network in the US, where
>     I peer
>     >> and buy upstream bandwidth in multiple locations in may cases
>     with the
>     >> same Networks.
>     >>
>     >> We currently run OSPF as in IGP and carry IBGP over loopbacks
>     for bgp
>     >> route distribution. Recently we have implemented MPLS for many
>     obvious
>     >> reasons and in doing so changed the way our customer traffic flows
>     >> dramatically.  This from what I can tell is due to route
>     preference,
>     >> where before MPLS a flow would be looked up at every hop and
>     might be
>     >> handed to a connected AS more locally to the origination of the
>     flow (A
>     >>  good thing).  Now with MPLS when the flow is setup it is never
>     looked
>     >> at again from an IP standpoint and therefore leaves my route
>     preference
>     >> using the last resort, router-id.  This as anyone knows is
>     plain old
>     >> wrong in this case and is hurting my traffic in more ways then one.
>     >>
>     >> Looking and testing I have had absolutely no luck setting the
>     IBGP core
>     >>  to use IGP metrics for route preference, nor have I had any
>     luck with
>     >> external router id (At this point I will try anything).  My
>     OSPF links
>     >> are all set with specific Metrics and flow just the way they
>     should but
>     >>  my hope is that I can get my BGP route table to use either the
>     metric
>     >> or the metric2 as the last resort tie breaker for prefix next-hops
>     >> instead of the IBGP router-id.
>     >>
>     >> I have tested this in junos 7.3 and 8.2 with no luck.  I have also
>     >> tried policies such as metric add 0 but still have no metrics
>     in the bgp
>     >> route table.  Have I been assuming that this feature does
>     something
>     >> completely different then what I have read it can do?  Does
>     anyone out
>     >> there have any suggestions as to how to use the most locally
>     (Closest
>     >> OSPF metric'd
>     >> IBGP neighbor) learned next-hop for a prefix?  Am I left to
>     manually set
>     >>  all the metrics on outbound routes in my core to force each
>     router to
>     >> use the more locally learned route?
>     >>
>     >> I thank you all for your help in advance and take care.. //db
>     >>
>     >>
>     >>
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