[c-nsp] Preloading AS to static network entry via route-map: Duh?

[Ramcharan, Vijay A]

I've never used that method to do as-prepending but I tried it in a lab
and it didn't work. Perhaps I'm missing something as well. 

Reading the BGP-4 handbook by Parkhurst, page 250 says that "In theory,
these commands allow you to modify a network's BGP attributes. In our
experience, they are too buggy and should not be used."

I used the same route-map in a neighbor statement and it as-prepended as
expected. 

router bgp 2
 bgp log-neighbor-changes
 neighbor 10.0.50.4 remote-as 4
 neighbor 10.0.50.5 remote-as 5
 !
 address-family ipv4
  neighbor 10.0.50.4 activate
  neighbor 10.0.50.4 route-map asprepend out	===> WORKS
  neighbor 10.0.50.5 activate
  no auto-summary
  no synchronization
  network 1.1.1.0 mask 255.255.255.0 route-map asprepend ===> Doesn't do
anything 
 exit-address-family
!
route-map asprepend permit 10
 set as-path prepend 2 2 2
!

Downstream-2600-4#show ip bgp 
BGP table version is 19, local router ID is 10.0.50.4
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*  1.1.1.0/24       10.0.50.2                0             0 2 2 2 2 i
*>                  10.0.0.5                               0 1 5 2 i
Downstream-2600-4#

Vijay Ramcharan 


> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Elmar K. Bins
> Sent: Monday, January 17, 2011 10:11 AM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Preloading AS to static network entry via route-map:
Duh?
> 
> Re guys,
> 
> the prefixes I give out are being rooted by "network" entries with
> a route-map attached (like "network a.b.c.d/e route-map <rm>").
> 
> In that route-map, I'm simply prepending an ASN ("as-path prepend
<as>").
> 
> Well - that prepend never makes it to the outside world. Source ASN is
> simply my ASN, the desired <as> is nowhere to be found.
> 
> Am I wrong in assuming it should work that way?
> 
> Oh, platform is an ASR1002, IOS-XE 12.2(33)XNC1t.
> 
> Didn't try my 7301s yet...
> 
> Elmar.
> 
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