[j-nsp] Juniper BGP Route Metrics
Otto Kreiter
otto.kreiter at dante.org.uk
Wed May 16 11:48:45 EDT 2007
Hi Dan,
Is LDP enabled in your whole network or just on some of the routers ?
I expect that all your BGP next-hops, or at least the ones from the LDP
enabled routers, to be present in the inet.3 route table, and because
BGP inspects inet.3 as well for BGP next-hops and LDP routes have a
lower preference that OSPF the LDP route will be selected to forward the
packets.
You can check it with:
show route table inet.3
One option may be to raise the preference of the LDP routes and then
your IGP routes in inet.0 may have a better preference or disable
"traffic-engineering bgp" which if I remember correctly is enabled by
default and enables BGP to use the routesin inet.3. But I'm not sure
which will suit you.
I hope it helps.
Cheers,
Otto
Dan Benson wrote:
> 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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>
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