Re: BGP AS-PATH PREPEND

Yea sorry that prefix list was a bit messy, but i think you get the Jist of
it (remove deny in the "ip prefix-list AS_CHANGE *deny*") to much copy and
paste se action going on from your emails :)

On Wed, Jan 8, 2014 at 5:15 PM, Sam Bibby <sammybibs_at_gmail.com> wrote:

> Oh I see, so you want to pre-pend everything except that one route, well
> that possible, Try then changing the things so as to deny the route you
> don't want to pre-pend & permit everything else
>
>
> !
> router bgp 65500
> neighbor 10.255.0.26 route-map AS_CHANGE out
> !
> route-map AS_CHANGE permit 10
> match ip address prefix OVER_L2
>
> set as-path prepend 65500 65500 65500
> !
> ip prefix-list AS_CHANGE deny
> ip access-list extended OVER_L2 deny X.X.X..X/XX *!!!the orute
> you dont want to prepend*
> ip access-list extended OVER_L2 permit 0.0.0.0/0 le 32 *!!!Permit
> everything else to get prepended*
>
>
>
> Without a full understanding of the topology I have to make some
> assumptions & I am trying to understand your issue a bit better,
>
> *1)Because I only want 10.100.60.11 (source) to go over Layer 2 (a name)
> 10.20.80.11 (destination). The rest should all be prepended. *
>
> *I don't see a route to 10.20.80.11 in the bgp output you send over:*
>
> R1#sh ip bgp
> > BGP table version is 196, local router ID is 10.255.255.2
> > Status codes: s suppressed, d damped, h history, * valid, > best, i -
> > internal,
> > r RIB-failure, S Stale, m multipath, b backup-path, x
> > best-external, f RT-Filter
> > Origin codes: i - IGP, e - EGP, ? - incomplete
> > Network Next Hop Metric LocPrf Weight Path
> > *> 10.3.0.0/16 0.0.0.0 0 32768 ?
> > *> 10.7.0.0/24 0.0.0.0 0 32768 ?
> > *> 10.11.0.0/24 0.0.0.0 0 32768 ?
> > *> 10.13.0.0/16 10.255.255.1 0 1 65501 ?
> > * 10.255.0.26 0 0 65501 65501
> 65501 65501 ?
> > *> 10.16.0.0/24 0.0.0.0 0 32768 ?
> > *> 10.20.0.0/24 10.255.255.1 0 1 65501 ?
> > * 10.255.0.26 28416 0 65501 65501 65501 65501 ?
>
>
> \Sam
>
>
>
> On Wed, Jan 8, 2014 at 4:53 PM, Cisco Fanatic <ebay_products_at_hotmail.com>wrote:
>
>> Because I only want 10.100.60.11 (source) to go over Layer 2 (a name)
>> 10.20.80.11 (destination). The rest should all be prepended.
>>
>> ip access-list extended OVER_L2
>> permit ip host 10.100.60.11 host 10.20.80.11
>>
>> With your suggestion all the traffic will be prepended (longer AS path)
>> and it will not be the best route.
>>
>>
>> ------------------------------
>> Date: Wed, 8 Jan 2014 16:36:40 +0000
>>
>> Subject: Re: BGP AS-PATH PREPEND
>> From: sammybibs_at_gmail.com
>> To: ebay_products_at_hotmail.com
>> CC: mothafungla_at_gmail.com; ccielab_at_groupstudy.com
>>
>>
>> I'm pretty sure the route map is wrong here,
>>
>> *!!!Yours*
>> !
>> *!You match the ACL but don't do anything with it.*
>> !
>> route-map AS_CHANGE permit 10
>> match ip address OVER_L2
>> !
>> *! You then pre-pend everything via the match all in the next statement*
>> !
>> route-map AS_CHANGE permit 20
>> set as-path prepend 65500 65500 65500
>> !
>>
>> *!!!Suggestion*
>> !
>> !You match the ACL but don't do anything with it.
>> !
>> route-map AS_CHANGE permit 10
>> match ip address OVER_L2
>> set as-path prepend 65500 65500 65500
>> !
>>
>> \Sam
>>
>>
>> On Wed, Jan 8, 2014 at 4:31 PM, Cisco Fanatic <ebay_products_at_hotmail.com>wrote:
>>
>> Sorry, cut-paste issue, too many notepad open.
>>
>> R1
>> ++
>>
>> !
>> router bgp 65500
>> neighbor 10.255.0.26 route-map AS_CHANGE out
>> !
>> route-map AS_CHANGE permit 10
>> match ip address OVER_L2
>> !
>> route-map AS_CHANGE permit 20
>> set as-path prepend 65500 65500 65500
>> !
>> ip access-list extended OVER_L2
>> permit ip host 10.100.60.11 host 10.20.80.11
>> !
>>
>> It is still going over the other connection...
>>
>> R1#traceroute 10.20.80.11
>> Type escape sequence to abort.
>> Tracing the route to 10.20.80.11
>> VRF info: (vrf in name/id, vrf out name/id)
>> 1 10.255.255.1 4 msec 0 msec 4 msec
>> 2 10.255.255.22 [AS 1] 4 msec 0 msec 4 msec
>> 3 10.13.0.253 [AS 65501] 4 msec 4 msec 0 msec
>>
>>
>>
>>
>>
>>
>> > Subject: Re: BGP AS-PATH PREPEND
>> > From: mothafungla_at_gmail.com
>> > Date: Wed, 8 Jan 2014 15:59:21 +0000
>> > CC: ccielab_at_groupstudy.com
>> > To: ebay_products_at_hotmail.com
>> >
>> > Where's your match extended ACL in route-map condition ?
>> >
>> > --
>> > BR
>> >
>> > Tony
>> >
>> > > On 8 Jan 2014, at 15:47, Cisco Fanatic <ebay_products_at_hotmail.com>
>> wrote:
>> > >
>> > > I understand how AS-PATH PREPEND works, but I am not able to make it
>> work
>> if I
>> > > need to manipulate traffic paths only from a specific source to a
>> specific
>> > > destination.
>> > >
>> > > R1
>> > > ++
>> > >
>> > > !
>> > > router bgp 65500
>> > >
>> > > neighbor 10.255.0.26 route-map AS_CHANGE out
>> > >
>> > > !
>> > > route-map AS_CHANGE permit 10
>> > >
>> > > set as-path prepend 65500 65500 65500
>> > >
>> > > !
>> > >
>> > > R2
>> > > ++
>> > >
>> > > !
>> > > router bgp 65501
>> > >
>> > > neighbor 10.255.0.25 route-map AS_CHANGE out
>> > >
>> > > !
>> > > route-map AS_CHANGE permit 10
>> > >
>> > > set as-path prepend 65501 65501 65501
>> > >
>> > > !
>> > >
>> > > R1#sh ip bgp
>> > > BGP table version is 196, local router ID is 10.255.255.2
>> > > Status codes: s suppressed, d damped, h history, * valid, > best, i -
>> > > internal,
>> > > r RIB-failure, S Stale, m multipath, b backup-path, x
>> > > best-external, f RT-Filter
>> > > Origin codes: i - IGP, e - EGP, ? - incomplete
>> > > Network Next Hop Metric LocPrf Weight Path
>> > > *> 10.3.0.0/16 0.0.0.0 0 32768 ?
>> > > *> 10.7.0.0/24 0.0.0.0 0 32768 ?
>> > > *> 10.11.0.0/24 0.0.0.0 0 32768 ?
>> > > *> 10.13.0.0/16 10.255.255.1 0 1 65501
>> ?
>> > > * 10.255.0.26 0 0 65501
>> 65501
>> 65501
>> > > 65501 ?
>> > > *> 10.16.0.0/24 0.0.0.0 0 32768 ?
>> > > *> 10.20.0.0/24 10.255.255.1 0 1 65501
>> ?
>> > > * 10.255.0.26 28416 0 65501
>> 65501
>> 65501
>> > > 65501 ?
>> > >
>> > > I need specific traffic from 10.100.60.11 (Source) to specific
>> 10.20.80.11
>> > > (Destination) over the 10.255.0.26 connection.
>> > >
>> > >
>> > > 10.100.60.11
>> > > _` 10.20.80.11
>> > >
>> > >
>> > > Any thoughts?
>> > >
>> > >
>> > > Blogs and organic groups at http://www.ccie.net
>> > >
>> > >
>> _______________________________________________________________________
>> > > Subscription information may be found at:
>> > > http://www.groupstudy.com/list/CCIELab.html
>> >
>> >
>> > Blogs and organic groups at http://www.ccie.net
>> >
>> > _______________________________________________________________________
>> > Subscription information may be found at:
>> > http://www.groupstudy.com/list/CCIELab.html
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Wed Jan 08 2014 - 17:17:50 ART