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New Member

Set AS-PATH prepend by matching RT value during import

Hi,

Can some one please explain how to match RT value and set AS-PATH prepend while importing the routes in to a VRF ?

I know AS-PATH prepention can be done with export-map when exporting routes along with setting a RT value. But for some reason this can't be done while importing to the VRF. Please help 

Thanks in advance,

Anil.

3 REPLIES
Cisco Employee

Set AS-PATH prepend by matching RT value during import

Anil,

This may not be possible. Use of import map is to have a finer control (whether to import or not) over prefixes allowed through the import RT list already defined for the VRF. This is simply a filtering mechanism and controling attirbutes may not be possible.

http://www.cisco.com/en/US/docs/net_mgmt/vpn_solutions_center/1.1/user/guide/VPN_UGB.html#wp1003958

regards

Ashish

Cisco Employee

Set AS-PATH prepend by matching RT value during import

Anil,

I did some more research and tested it to be working. you were not able to set AS-PATH prepend in an import-map due to the following bug.

I tested the workaround in my lab. If you set local-preference along with as-path prepend then it works fine.

CSCtj85371            Bug Details

import map with as-path prepend

Symptom:
AS_PATH prepend will only work if there is LOCAL  PREF defined inside a outbound routemap. If there is only AS_PATH  prepend and no LOCAL_PREF, BGP will not prepend the paths with defined  AS values.
Conditions:
AS PATH prepend will not be pre-pended properly
Workaround:
Configure LOCAL_PREF along with AS_PATH prepend

Fixed-In

15.0(1)M4.5

15.1(3.13)T

12.2(33)SRE3

12.2(33.2.20)SRE

15.1(1)S0.2

15.1(1.22)S

15.0(1.19)DPA12

15.1(3.8.3)PIB

15.2(0.0.12)PIL16

15.0(1)S2.3

15.1(2)T2.2

15.1(1)T2.4

15.1(3)T0.2

15.1(1)S1

15.0(1.19)DPB23

15.0(2.12)DPB1

15.0(1)SY

15.1(1)SG1.3

15.0(1)S3a

15.1(2)GC1

15.1(1)MR3

New Member

Set AS-PATH prepend by matching RT value during import

Hi Ashish,

I also did the same , it worked after setting local pref while impporting.

Many thanks for the support.

Thanks,

Anil.

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