From: Larry (cc13lab@gmail.com)
Date: Wed Feb 06 2008 - 13:35:46 ARST
Metric is not used in this calculation, admin distance is. The defualt admin
distance is used when there is a tie. Route preference:
1. longest match
2. admin distance
3. if equal default AD, then use metric to determine best route.
4. if equal metric, loadbalance equal cost paths.
The metric is not used until like routes are found in a single protocol.
Metrics are not distinguishable between different protocols so to use metric
between them would be useless (metric of 20 in ospf and eigrp have 2
completely different meanings). HTH
larry
On 2/6/08, Joel Amao <femmy79@hotmail.com> wrote:
>
> Same AD but different metric ...Thats why.
>
>
> In your output below:
> static -0
> ospf-2
>
>
>
>
>
> Joel Amao
> CCIE#18128
>
>
>
> > From: joe@affirmedsystems.com
> > To: cc13lab@gmail.com
> > CC: ccielab@groupstudy.com
> > Subject: RE: Route preference
> > Date: Tue, 5 Feb 2008 12:00:46 -0500
> >
> > >So, if a router is learning 192.168.1.0/24 through ospf and there is a
> > static route for 192.168.1.0/24 with AD of 110. Thank you in advance.
> >
> >
> >
> > Read this part. both routes have an AD of 110.
> >
> >
> >
> > So here goes,
> >
> >
> >
> > I lab'd it up.
> >
> >
> >
> > rack1r1#sh ip route ospf
> >
> > 1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
> >
> > O 1.1.13.0/24 [110/2] via 172.16.11.11, 00:00:02, FastEthernet0/0
> >
> > (towards sw1)
> >
> >
> >
> > But, when I put the static route with ad 110,
> >
> >
> >
> > ip route 1.1.13.0 255.255.255.0 172.16.11.11 110
> >
> >
> >
> > it uses the static route instead of ospf
> >
> >
> >
> > rack1r1#sh ip route 1.1.13.1
> >
> > Routing entry for 1.1.13.0/24
> >
> > Known via "static", distance 110, metric 0
> >
> > Routing Descriptor Blocks:
> >
> > * 172.16.11.11
> >
> > Route metric is 0, traffic share count is 1
> >
> >
> >
> >
> >
> > rack1r1#sh ip route ospf
> >
> >
> >
> >
> >
> > (nothing)
> >
> >
> >
> > LOL, I guess even with same AD you can't use two TYPES of routes to load
> > balance.
> >
> >
> >
> > -Joe
> >
> >
> >
> >
> >
> > _____
> >
> > From: Larry [mailto:cc13lab@gmail.com]
> > Sent: Tuesday, February 05, 2008 11:30 AM
> > To: Joseph Brunner
> > Cc: ccielab@groupstudy.com
> > Subject: Re: Route preference
> >
> >
> >
> > That should be a 1 not a 0...
> >
> >
> >
> > default ad = 0
> >
> >
> >
> > On 2/5/08, Larry <cc13lab@gmail.com> wrote:
> >
> > Only the static route would be put into the table as its default ad = 0:
> >
> >
> >
> > r1#show ip route 150.1.3.3 <http://150.1.3.3/>
> > Routing entry for 150.1.3.3/32
> > Known via "ospf 1", distance 110, metric 65, type intra area
> > Last update from 150.1.13.3 <http://150.1.13.3/> on Serial1/1, 00:00:26
> > ago
> > Routing Descriptor Blocks:
> > 150.1.13.3 <http://150.1.13.3/> , from 150.1.3.3 <http://150.1.3.3/> ,
> > 00:00:26 ago, via Serial1/1
> > Route metric is 65, traffic share count is 1
> > * 150.1.12.2 <http://150.1.12.2/> , from 150.1.2.2 <http://150.1.2.2/> ,
> > 00:00:26 ago, via Serial1/0.1
> > Route metric is 65, traffic share count is 1
> >
> > r1#conf t
> > Enter configuration commands, one per line. End with CNTL/Z.
> > r1(config)# ip route 150.1.3.3 <http://150.1.3.3/> 255.255.255.255
> > <http://255.255.255.255/> 150.1.13.3 <http://150.1.13.3/> 110
> > r1(config)#^Z
> > r1#show ip route 150.1.3.3 <http://150.1.3.3/>
> > Routing entry for 150.1.3.3/32
> > Known via "static", distance 110, metric 0
> > Routing Descriptor Blocks:
> > * 150.1.13.3 <http://150.1.13.3/>
> > Route metric is 0, traffic share count is 1
> >
> > -larry
> >
> >
> >
> > On 2/5/08, Joseph Brunner <joe@affirmedsystems.com> wrote:
> >
> > Both would be in the routing table. But there will no load balancing
> unless
> > cef is disabled (no ip cef). With cef the OLDEST or first learned route
> is
> > USED only... so if you want true load balancing using the routing table,
> > disable cef.
> >
> > josCEF
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Robert CCIE
> > Sent: Monday, February 04, 2008 8:07 PM
> > To: ccielab@groupstudy.com
> > Subject: Route preference
> >
> > Hello Everyone,
> > I was just wondering how a router behaves in these situations. If a
> > router learns a route through a routing protocol but there is a static
> > route with the same admin distance configured. Which route would be
> > installed in the routing table? Or would both be installed? Also, I'm
> > guessing metrics only matter for that routing protocols process as far
> > as calculation since a static route has a metric of 0.
> >
> > So, if a router is learning 192.168.1.0/24 through ospf and there is a
> > static route for 192.168.1.0/24 with AD of 110. Thank you in advance.
> >
> > -Robert
> >
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