Re: BGP Question

I don't see anything in the document that suggests RTC has some alternate
route to 129.213.1.0. Even if it did, the AD on the eBGP learned route would
prevent it from entering the route table (without the use of the bgp
backdoor feature). I'm guessing this is a mistake.

On Tue, Oct 25, 2011 at 7:13 AM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:

> Kirk,
> this paragraph is wrong. There is no such thing as transitive
> redistribution in cisco gear, and RTC will not reoriginate the
> 129.213.1.0 network even if you do mutual redistribution without
> filters.
>
> Problems with cross redistribution arise when you have at least 2 points
> of mutual redistribution...
>
> -Carlos
>
>
> Kirk Douglas @ 25/10/2011 3:06 -0300 dixit:
>
> I was reading the BGP Case Studies on Cisco's site at this link:
>>
>> http://www.cisco.com/en/US/**tech/tk365/technologies_tech_**
>> note09186a00800c95bb.shtml<http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c95bb.shtml>
>>
>> It states:
>>
>> The network command is one way to advertise your networks via BGP. Another
>> way is to redistribute your IGP into BGP. Your IGP can be IGRP, Open
>> Shortest Path First (OSPF) protocol, RIP, Enhanced Interior Gateway
>> Routing
>> Protocol (EIGRP), or another protocol. This redistribution can seem scary
>> because now you dump all your internal routes into BGP; some of these
>> routes
>> can have been learned via BGP and you do not need to send them out again.
>> Apply careful filtering to make sure that you send to the Internet-only
>> routes that you want to advertise and not to all the routes that you have.
>> Here is an example:
>>
>> RTA announces 129.213.1.0 and RTC announces 175.220.0.0. Look at the RTC
>> configuration:
>>
>> If you issue the network command, you have:
>>
>> RTC#
>> router eigrp 10
>> network 175.220.0.0
>> redistribute bgp 200
>> default-metric 1000 100 250 100 1500
>>
>> router bgp 200
>> neighbor 1.1.1.1 remote-as 300
>> network 175.220.0.0 mask 255.255.0.0
>>
>> !--- This limits the networks that your AS originates to 175.220.0.0.
>>
>> If you use redistribution instead, you have:
>>
>> RTC#
>> router eigrp 10
>> network 175.220.0.0
>> redistribute bgp 200
>> default-metric 1000 100 250 100 1500
>>
>> router bgp 200
>> neighbor 1.1.1.1 remote-as 300
>> redistribute eigrp 10
>>
>> !--- EIGRP injects 129.213.1.0 again into BGP.
>>
>>
>> If you take a look at diagram in the link for this secition you will get a
>> better understanding of my question. Read from the part where it states
>> "*This
>> redistribution can seem scary because now you dump all your internal
>> routes
>> into BGP; some of these routes can have been learned via BGP and you do
>> not
>> need to send them out again*" after looking at the diagram. It also states
>> "
>> *EIGRP injects 129.213.1.0 again into BGP*" at the end. This seems wrong
>> to
>> me but please let me know if I am mistaken. My question is about the
>> ""*EIGRP
>> injects 129.213.1.0 again into BGP*". If eigrp 10 is redistributing bgp
>> routes to the neighbor then the neighbor wouldn't advertise those routes
>> back to RTC where it is redistributing eigrp 10 into bgp 200. If so, then
>> how can EIGRP inject 129.213.1.0 back into BGP?
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> ______________________________**______________________________**
>> ___________
>> Subscription information may be found at: http://www.groupstudy.com/**
>> list/CCIELab.html <http://www.groupstudy.com/list/CCIELab.html>
>>
>>
>>
>>
>>
>>
>>
>>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>
>
>
> Blogs and organic groups at http://www.ccie.net
>
> ______________________________**______________________________**
> ___________
> Subscription information may be found at: http://www.groupstudy.com/**
> list/CCIELab.html <http://www.groupstudy.com/list/CCIELab.html>

Blogs and organic groups at http://www.ccie.net
Received on Tue Oct 25 2011 - 09:33:57 ART