Re: BGP conditional adv??

Ooh, very funny :)) Specially 10 days before my exam :))

On Fri, Feb 26, 2010 at 9:22 PM, Narbik Kocharians <narbikk_at_gmail.com> wrote:
> Guys i know it does work, he is referring to one of my labs, i was joking
> with him, because he used patch instead of path.
>
> On Fri, Feb 26, 2010 at 2:25 AM, Tolulope Ogunsina <togunsina_at_gmail.com>
> wrote:
>>
>> Yes, I just did.
>> Assume we have R1, R2,R3 and R4 in AS 1, 2,3 and 4 respectively
>> R1 -- R4 --- R3
>> |
>> R2
>>
>> R1, R2, and R3 advertise 150.1.x.0/24 into bgp where x is the router
>> number.
>>
>> R4 aggregates the routes to 150.1..0.0/16 with as-set attribute.
>> By default, none of the routers get the update anymore since their
>> individual routes are a part of the summary.
>>
>> Using advertise map, we want to make R1 and R3 get the summary; so we
>> only advertise the attributes of the prefix form R2 with the summary.
>> Using as path access-lists and route-maps on R4 we have,
>>
>> ip as-path access-list 1 permit ^2$
>> route-map adv permit 10
>> match as-path 1
>>
>> router bgp 4
>> aggregate-address 150.1.0.0 255.255.0.0 as-set summary-only advertise-map
>> adv
>>
>> Now, R1 and R3 get the summary, R2 doesn't because its AS number is
>> carried along with the summary
>>
>> R1(config-router)#do sh ip bg | i 150.1.0.0
>> *> 150.1.0.0 192.168.1.4 0 0 4 2 i
>>
>> R2(config-router)#do sh ip bg | i 150.1.0.0
>> R2(config-router)#
>>
>> HTH,
>>
>> On 2/26/10, Ruhann <groupstudy_at_ru.co.za> wrote:
>> > Have you labbed this?
>> >
>> > On Fri, Feb 26, 2010 at 10:54 AM, Tolulope Ogunsina
>> > <togunsina_at_gmail.com>
>> > wrote:
>> >> Yes, for conditional route advertisement.
>> >>
>> >> Advertise-maps in conditional advertisement and Route aggregation
>> >> (using the aggregate-address command) perform two entirely different
>> >> functions.
>> >>
>> >> In the latter, the advertise map specifies the "Name of the route map
>> >> used to select the routes to create AS_SET origin communities."
>> >>
>> >> On 2/26/10, Ruhann <groupstudy_at_ru.co.za> wrote:
>> >>> Conditional Route advertisement is meant to watch a route. I am not so
>> >>> sure it will work the way you want, matching a AS-Path filter..
>> >>>
>> >>> It watches a Prefix in the table (the watch route), and if that prefix
>> >>> dissapear it then advertises another prefix (the advertise prefix)
>> >>>
>> >>> On Thu, Feb 25, 2010 at 5:35 PM, Ivan Hrvatska <ivanzghr_at_gmail.com>
>> >>> wrote:
>> >>>> OK. I think I get it. Correct me if I'm wrong:
>> >>>>
>> >>>> if my agg route has {100,300} which are AS numbers of R1 and R3, R1
>> >>>> and R3 will discard that agg prefix cause they see it's own AS
>> >>>> number.
>> >>>> When I do this, on the R2 which is originator of agg rute:
>> >>>>
>> >>>> ip as-patch acl 1 per ^300$
>> >>>> route-map XXX
>> >>>> match as-patch 1
>> >>>> router bgp 200
>> >>>> agg-add 3.1.0.0 255.255.240.0 summ-only as-set adv-map XXX
>> >>>>
>> >>>> I'm actually permitting only ASN 300 in AS_PATH, so R1 will process
>> >>>> agg route and install it in BGP table cause it doesn't see it's AS
>> >>>> number. R3 will discard it. Is this correct? Is this the
>> >>>> functionality
>> >>>> of adv-map with aggregation?
>> >>>>
>> >>>> Regards
>> >>>>
>> >>>> On Thu, Feb 25, 2010 at 2:47 PM, Tolulope Ogunsina
>> >>>> <togunsina_at_gmail.com>
>> >>>> wrote:
>> >>>>> Hi,
>> >>>>> The advertise-map in aggregate address command is different from the
>> >>>>> advertise map in conditional advertisements.
>> >>>>> In aggregate address, the advertise-map argument is the "Name of the
>> >>>>> route map used to select the routes to create AS_SET origin
>> >>>>> communities"
>> >>>>>
>> >>>>> With that said, I do NOT fully understand the scenario you're
>> >>>>> describing. Please shed some more light.
>> >>>>>
>> >>>>> On 2/25/10, Ivan Hrvatska <ivanzghr_at_gmail.com> wrote:
>> >>>>>> Oh, yea. I didn't read carefully :) First bullet will be done by
>> >>>>>> default. Third bullet will also be done by default. So, the second
>> >>>>>> bullet is actually going through the task on reverse way. If
>> >>>>>> 1.0.0.0
>> >>>>>> is DOWN, nothing is going to be advertised, and if it is UP, only
>> >>>>>> 2.0.0.0 will be advertised. OK. I get it. I was confused by the way
>> >>>>>> the task is given.
>> >>>>>>
>> >>>>>> As I go further through the BGP i have one more issue.
>> >>>>>> One task:
>> >>>>>>
>> >>>>>> R1------R2-------R3
>> >>>>>>
>> >>>>>> R3 has couple of specific nets which are aggregated by R2. R1 only
>> >>>>>> gets aggregate prefix without atomic-agg attribute (summary-only
>> >>>>>> and
>> >>>>>> as-set is used). The aggregation should be configured such that R1
>> >>>>>> in
>> >>>>>> AS 100 is the only AS that recivies agg route. R3 or future peer
>> >>>>>> neighbors should NOT receive the agg route.
>> >>>>>> Solution:
>> >>>>>> ip as-path access-list 1 permit ^300$
>> >>>>>> route-map TST per 10
>> >>>>>> match as-path 1
>> >>>>>> agg 3.1.0.0 255.255.240.0 as-set summ-only adv-map TST
>> >>>>>>
>> >>>>>> First, I planned to solve this task with community no-export. R2
>> >>>>>> sets
>> >>>>>> that comm to the agg route and send it to R1.
>> >>>>>> I don't het what this route-map exactly does in this case? as-path
>> >>>>>> acl
>> >>>>>> matches prefixes originated in AS 300. What else in combination
>> >>>>>> with
>> >>>>>> agg-add command?
>> >>>>>>
>> >>>>>> regards
>> >>>>>>
>> >>>>>> On Thu, Feb 25, 2010 at 11:20 AM, Tolulope Ogunsina
>> >>>>>> <togunsina_at_gmail.com>
>> >>>>>> wrote:
>> >>>>>>> The solution means advertise 2.0.0.0 if (and only if) 1.0.0.0
>> >>>>>>> exists
>> >>>>>>> which also means if 1.0.0.0 does NOT exist, do NOT advertise
>> >>>>>>> 2.0.0.0.
>> >>>>>>>
>> >>>>>>> On 2/25/10, Ivan Hrvatska <ivanzghr_at_gmail.com> wrote:
>> >>>>>>>> Yes, that is true. But shouldn't solution be: if 1.0.0.0/8 is
>> >>>>>>>> DOWN,
>> >>>>>>>> do
>> >>>>>>>> NOT advertise 2.0.0.0:
>> >>>>>>>>
>> >>>>>>>> in solution in route-map EXIST you are matching 1.0.0.0, which
>> >>>>>>>> means,
>> >>>>>>>> if 1.0.0.0 exist in RIB, advertise what you permit in route-map
>> >>>>>>>> ADV,
>> >>>>>>>> and in route-map ADV you permit 2.0.0.0. That's what is confusing
>> >>>>>>>> to
>> >>>>>>>> me.
>> >>>>>>>>
>> >>>>>>>> On Thu, Feb 25, 2010 at 9:32 AM, Tolulope Ogunsina
>> >>>>>>>> <togunsina_at_gmail.com>
>> >>>>>>>> wrote:
>> >>>>>>>>> Hi Ivan,
>> >>>>>>>>> From the question,
>> >>>>>>>>>
>> >>>>>>>>> - if both nets 1.0.0.0 and 2.0.0.0 are up, R1 should advertise
>> >>>>>>>>> them
>> >>>>>>>>> both
>> >>>>>>>>> - if 1.0.0.0/8 is DOWN, R1 should not advertise 2.0.0.0/8 to R3
>> >>>>>>>>> - if 2.0.0.0/8 is DOWN, R1 should only advertise net 1.0.0.0/8
>> >>>>>>>>> to
>> >>>>>>>>> R3
>> >>>>>>>>>
>> >>>>>>>>> network 2.0.0.0/8 is dependent on 1.0.0.0/8. (second
>> >>>>>>>>> requirement).
>> >>>>>>>>> 1st and third requirements are the default behavior of the BGP
>> >>>>>>>>> process.
>> >>>>>>>>>
>> >>>>>>>>> Hence the solution only focuses on the second requirement.
>> >>>>>>>>>
>> >>>>>>>>> HTH,
>> >>>>>>>>>
>> >>>>>>>>> On 2/24/10, Ivan Hrvatska <ivanzghr_at_gmail.com> wrote:
>> >>>>>>>>>> Hi experts,
>> >>>>>>>>>>
>> >>>>>>>>>> I have some difficulties to catch this scenario with BGP
>> >>>>>>>>>> conditional
>> >>>>>>>>>> adv:
>> >>>>>>>>>>
>> >>>>>>>>>> R1-----------R2
>> >>>>>>>>>> |
>> >>>>>>>>>> |
>> >>>>>>>>>> R3
>> >>>>>>>>>>
>> >>>>>>>>>> R1 has lo0 1.1.1.1/8, R2 has Lo0 2.2.2.2/8 and R3 has also Lo0
>> >>>>>>>>>> 3.3.3.3/8. All RTs are in same AS and all of them advertise
>> >>>>>>>>>> their
>> >>>>>>>>>> loopbacks.
>> >>>>>>>>>> Task is next:
>> >>>>>>>>>> - if both nets 1.0.0.0 and 2.0.0.0 are up, R1 should advertise
>> >>>>>>>>>> them
>> >>>>>>>>>> both
>> >>>>>>>>>> - if 1.0.0.0/8 is DOWN, R1 should not advertise 2.0.0.0/8 to R3
>> >>>>>>>>>> - if 2.0.0.0/8 is DOWN, R1 should only advertise net 1.0.0.0/8
>> >>>>>>>>>> to
>> >>>>>>>>>> R3
>> >>>>>>>>>>
>> >>>>>>>>>> Solution on R1:
>> >>>>>>>>>> acl 1 permit 1.0.0.0 0.255.255.255
>> >>>>>>>>>> acl 2 permit 2.0.0.0 0.255.255.255
>> >>>>>>>>>>
>> >>>>>>>>>> route-map ADV per 10
>> >>>>>>>>>> match ip add 2
>> >>>>>>>>>> route-map EXIST per 10
>> >>>>>>>>>> match ip add 1
>> >>>>>>>>>>
>> >>>>>>>>>> router bgp 100
>> >>>>>>>>>> neighbor R3 adv-map ADV exist-map EXIST
>> >>>>>>>>>>
>> >>>>>>>>>> So, from my point of view this task should do next:
>> >>>>>>>>>> - if 1.0.0.0/8 is UP (2.0.0.0/8 can also be UP) advertise
>> >>>>>>>>>> 2.0.0.0/8
>> >>>>>>>>>> to
>> >>>>>>>>>> R3 (task asks you to NOT advertise)
>> >>>>>>>>>> - if 1.0.0.0/8 is DOWN (2.0.0.0/8 can also be DOWN), do not
>> >>>>>>>>>> advertise
>> >>>>>>>>>> anything
>> >>>>>>>>>>
>> >>>>>>>>>> This solution is correct, but I don't get the logic?
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>> Blogs and organic groups at http://www.ccie.net
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>> _______________________________________________________________________
>> >>>>>>>>>> Subscription information may be found at:
>> >>>>>>>>>> http://www.groupstudy.com/list/CCIELab.html
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>>
>> >>>>>>>>>
>> >>>>>>>>>
>> >>>>>>>>> --
>> >>>>>>>>> Best Regards,
>> >>>>>>>>>
>> >>>>>>>>> Tolulope.
>> >>>>>>>>>
>> >>>>>>>>
>> >>>>>>>
>> >>>>>>>
>> >>>>>>> --
>> >>>>>>> Best Regards,
>> >>>>>>>
>> >>>>>>> Tolulope.
>> >>>>>>
>> >>>>>>
>> >>>>>> Blogs and organic groups at http://www.ccie.net
>> >>>>>>
>> >>>>>>
>> >>>>>> _______________________________________________________________________
>> >>>>>> Subscription information may be found at:
>> >>>>>> http://www.groupstudy.com/list/CCIELab.html
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>
>> >>>>>
>> >>>>> --
>> >>>>> Best Regards,
>> >>>>>
>> >>>>> Tolulope.
>> >>>>
>> >>>>
>> >>>> Blogs and organic groups at http://www.ccie.net
>> >>>>
>> >>>>
>> >>>> _______________________________________________________________________
>> >>>> Subscription information may be found at:
>> >>>> http://www.groupstudy.com/list/CCIELab.html
>> >>>>
>> >>>>
>> >>>>
>> >>>>
>> >>>>
>> >>>>
>> >>>>
>> >>>>
>> >>>
>> >>>
>> >>>
>> >>> --
>> >>> <ruhann>
>> >>> www.routing-bits.com
>> >>>
>> >>>
>> >>> Blogs and organic groups at http://www.ccie.net
>> >>>
>> >>>
>> >>> _______________________________________________________________________
>> >>> Subscription information may be found at:
>> >>> http://www.groupstudy.com/list/CCIELab.html
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>
>> >>
>> >> --
>> >> Best Regards,
>> >>
>> >> Tolulope.
>> >>
>> >
>> >
>> >
>> > --
>> > <ruhann>
>> > www.routing-bits.com
>> >
>>
>>
>> --
>> Best Regards,
>>
>> Tolulope.
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>>
>>
>>
>>
>>
>>
>
>
>
> --
> Narbik Kocharians
> CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> www.MicronicsTraining.com
> Sr. Technical Instructor
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Received on Fri Feb 26 2010 - 23:01:10 ART