Another BGP challange 2

acidsatyracidsatyr Member Posts: 111
in CCIE 

 AS 20			.      AS 12
			.
			.	
R1------(122.12.1.0/24)-------R2
 |			.      |
 |			.      |
 |                      .      |
 (133.13.1.0/24)        .      |
 |                      .      |
 |                      .      |
 |                      .      |
 |                      .      |
R3------(10.23.1.0/24)---------
			.
			.
			.

Here's another quick challange, this time for BGP.
Assume full mesh and that peering is done on directly
connected interfaces.

Assume that R2 is advertising its network 2.2.2.0/24. Then,
configure BGP so that it matches output on R1:
   Network          Next Hop            Metric LocPrf Weight Path
* i2.2.2.2.0/24     10.23.1.2            0      100           0 12 i
*>                  122.12.1.2           0                    0 21 12 i


Config should be as simple as possible. Do not use route map on R1 or R2.
If you think you know the asnwer give others a chance to think.

:)
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Comments

  • ColbyGColbyG Member Posts: 1,264
    I'm confused.
    http://blog.alwaysthenetwork.com
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    Giving others a chance to think.
    An expert is a man who has made all the mistakes which can be made.
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  • acidsatyracidsatyr Member Posts: 111
    If you know the answer please give others chance to think. I know there are ppl here who find this easy but don't ruin it for everyone else
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  • TurgonTurgon Banned Posts: 6,308 ■■■■■■■■■□
    That 21 in the AS Path is interesting..

    0 21 12 i

    I will await your findings ;)
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  • Forsaken_GAForsaken_GA Member Posts: 4,024
    local-as
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  • notgoing2failnotgoing2fail Member Posts: 1,138
    augh! I haven't gotten to BGP yet! icon_redface.gif
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  • acidsatyracidsatyr Member Posts: 111
    Some people feel they might be more important than others.
    So anyway here's the solution:

    R1

    router bgp 20
    nei 122.12.1.2 remote 21
    bgp bestpath as-path ignore

    R2

    router bgp 12
    nei 122.12.1.1 local-as 21
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  • TurgonTurgon Banned Posts: 6,308 ■■■■■■■■■□
    acidsatyr wrote: »
    Some people feel they might be more important than others.
    So anyway here's the solution:

    R1

    router bgp 20
    nei 122.12.1.2 remote 21
    bgp bestpath as-path ignore

    R2

    router bgp 12
    nei 122.12.1.1 local-as 21

    Perhaps you can explain why there is no local pref value for the R2 advertised prefix
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  • acidsatyracidsatyr Member Posts: 111
    Because it is a well known discretionary attribute, meaning, it is not advertises from AS to AS. Same route from R3 has local pref of 100.
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  • TurgonTurgon Banned Posts: 6,308 ■■■■■■■■■□
    acidsatyr wrote: »
    Because it is a well known discretionary attribute, meaning, it is not advertises from AS to AS. Same route from R3 has local pref of 100.

    Spot on. Good stuff and keep them coming.
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