Re: BGP conditional adv??

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
Received on Thu Feb 25 2010 - 13:44:52 ART