From: Xuan.Sun@xxxxxxxxxxx
Date: Mon Aug 27 2001 - 13:22:10 GMT-3
The interested point is:
If you have two pathes, one is from EBGP peer, one is from IBGP peer. By
default, BGP takes the path from EBGP peer. But if you want to use the path
from IBGP peer, how to configure ? How to use Locale_Preference to do ? It
is the intention in this example.
If you can try in your lab, that will be great.
Jason Gardiner <gardiner@sprint.net>@sprint.net on 08/27/2001 05:21:33 AM
Sent by: gardiner@sprint.net
To: Xuan.Sun@Seagate.com
cc: ccielab@groupstudy.com
Subject: Re: LOCAL_PREF example in Doyle, Routing TCP/IP Volume II page
242
Hello,
I'm not sure how this exactly setup, but something you said is
interesting:
>>assigns a high Local_Pref number (300) on Moritz. It send to Zermatt.
Local pref is just that. Local. If you send routes to another AS, the
local pref gets dropped.
Xuan.Sun@Seagate.com wrote:
>
> Hi All
>
> I have posted a message talking about LOCAL_PREF before. I hit this
problem
> again when I tried the example on Dolye's book.
>
> The diagram and configuration are at Page 242-243. Dolye uses this
example
> to manipulate the LOCAL_PREFERENCE. So it will take the route to AS 50
> using Innsbruck, AS 75 using Saalbach.
>
> On Zermatt, there are two paths to reach AS 75, for example the route
> 172.18.0.0. It either takes Innsbruck or Moritz. The Innsbruck is the
EBGP
> peer. Moritz is the IBGP peer. Because the Innsbruck is the EBGP peer.
BGP
> always uses it as the next hop.
>
> Dolye assigns a high Local_Pref number (300) on Moritz. It send to
Zermatt.
> So on Zermatt, the next hop to 172.18.0.0 from Moritz increased to 300,
> instead of the default 100. So BGP will take Moritz as the next hop for
> 172.18.0.0. The "show ip BGP" is on Page 244.
>
> I have built up the same network and configuration. But it does not work
in
> the way as Dolye's. I can see the Locale_Pref has been changed to 300.
But
> BGP still takes Innsbruck. See my "show ip bgp" on Zermatt. I have
aligned
> the output. But it may not display on your machine.
>
> Have somebody tested this configuration before ? Did you have the same
> problem ? Is it a IOS bug ? I am using 3810, IOS 12.0.(7)T for Moritz and
> Zermatt.
>
> Your feedback is highly appeciated. I am tied to this Locale_Pref
> attribute.
>
> Zermatt#sh ip bgp
> BGP table version is 23, local router ID is 172.30.255.254
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight
Path
> * i10.20.0.0/16 172.30.255.150 100 0
100 50 ?
> *> 10.100.83.1 200 0
100 50 ?
> * i10.30.0.0/16 172.30.255.150 0 100 0
?
> *> 192.168.3.3 0 32768
?
> * i10.50.250.1/32 172.30.255.150 100 0
100 50 ?
> *> 10.100.83.1 200 0
100 50 ?
> * i10.75.100.1/32 172.30.255.150 100 0
100 50 ?
> *> 10.100.83.1 200 0
100 50 ?
> *> 10.100.65.1/32 10.100.83.1 200 0
100 50 ?
> *>i10.100.83.1/32 172.30.255.150 100 0
100 50 ?
> * i172.16.0.0 172.30.255.150 0 100 0
?
> *> 192.168.3.3 0 32768
?
> * i172.17.0.0 172.30.255.150 100 0
100 50 ?
> *> 10.100.83.1 200 0
100 50 ?
> * i172.18.0.0 172.30.255.150 300 0
100 75 i
> *> 10.100.83.1 0
100 75 i
> * i172.29.1.0/24 172.30.255.150 0 100 0
?
> *> 192.168.3.3 0 32768
?
> * i172.29.2.0/24 172.30.255.150 100 0
100 50 ?
> *> 10.100.83.1 200 0
100 50 ?
> *> 172.30.255.150/32
> 192.168.3.2 0 32768
?
> * i172.31.0.0 172.30.255.150 0 100 0 ?
> *> 192.168.3.3 0 32768
?
> * i192.168.50.0 172.30.255.150 100 0
100 50 ?
> *> 10.100.83.1 200 0
100 50 ?
> * i192.168.100.0 172.30.255.150 0 100 0
?
> *> 192.168.3.3 0 32768
?
> **Please read:http://www.groupstudy.com/list/posting.html
-- Thanks,Jason Gardiner Supervisor, Engineering Services Sprint E|Solutions
"You can swim all day in the Sea of Knowledge and still come out completely dry. Most people do."
- Norton Juster **Please read:http://www.groupstudy.com/list/posting.html
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