BGP as-path prepend for specific destination

[mirage]

Dear all,

I have a following topology in my lab:

R1 (as 208097) -- > R2 ISP (as16010)  -- R3 (as 35805)

                                                |

                                      R4 (as 10101)

I want to

prepend

my announce for AS35805 only with

as-path access-list

and

route-map

like this:

R1

interface FastEthernet0/0
ip address 2.2.2.1 netmask 255.255.255.252
duplex auto
speed auto

router bgp 20809
no synchronization
bgp router-id 1.1.1.254
bgp log-neighbor-changes
network 1.1.1.0 netmask 255.255.255.0
neighbor 2.2.2.2 remote-as 16010
neighbor 2.2.2.2 route-map BGP_OUT_RMAP out

ip as-path access-list 50 permit ^20809 16010 35805$
ip as-path access-list 50 deny .*

ip prefix-list MM seq 10 permit 1.1.1.0/24

route-map BGP_OUT_RMAP permit 10

match ip address prefix-list MM
match as-path 50
set as-path prepend 20809 20809

But it doesn't work

Does it possible?

[mirage]

Perfect answer,

But more details about my test:

I turned off R1 (main router) and bgp announce changed on R5(for example), but when it returns in active state, toute table does not change at R5 until I clear bgp session on R2 (backup router). What is a solution for returning best path again on R5 except EEM (I can configure EEM event on R2 when R1 returns in active state)?

Thanks in advance.

[MHM Cisco World]

Both primary and backup in same as' run bfd it will immediately detect neighbor up/down fast than depend on bgp hello.

[mirage]

I thy this way too, and will write results..

[mirage]

Done without bfd, there was little misconfiguration.

Many thanks for all!

[MHM Cisco World]

and from me and all you are so welcome