BGP advertise-map in XOS

[Elie_Raad]

I have a Multi-homed Routers connected to 2 ISPs. I need to Create like an Advertise-map on the Standby Router connected to the Standby ISP to only advertise my Public address if the primary link goes down .

Is there a way of doing it in XOS ?
Thank You,
Elie

[Jarek]

Elie,

This is only an idea and I don't have a time to put it all together, but...
lets assume you have scenario like this bellow:

Router Expedient - Low speed link
/
Your Standby Router (EXOS switch)
|
|
|
Your Main Router (EXOS switch)
\
Router Cogent - High speed link

You advertise your prefix for example 10.0.0.0/24 from Main router:
- dirtect to Cogent
- to Standby Router and then to Expedient

On Main Router you can have a UPM script and BGP export policy.

The UPM script will check if some route is in table and this route nexthop is via Cogent
or if the session is up and so on.
If the route does not exists, you apply iBGP_export_Stby.pol to iBGP peer out to Standby Router
and advertise prefix with community 65535:100
If all is ok, unconfigure policy iBGP_export_Stby.pol

================= iBGP_export_Stby.pol =====================

entry iBGP_peer_Main { if match all {
nlri 10.0.0.0/24;
} then {
permit;
community set 65535:100;
}}

========================================================

On Stanby Router you can have a policy that import prefix from Main router like this:
If I receive my prefix from IBGP peer Main Router with community 65535:100
then I will permit and then advertise to Expedient.
If not deny the prefix and don't advertise anything.

example
========== iBGP_import_Main.pol =============================
entry iBGP_peer_Main { if match all {
community 65535:100;
nlri 10.0.0.0/24;
} then {
permit;
}}

entry IP_BGP_deny { if {
} then {
deny;
}}
===========================================================

--
Jarek

[EtherMAN]

I hate to agree with the others here but your first step has to be working with the upstream provider you are paying good money to for the best way they would support your scenario. They each have their own rules on how they will send traffic back to you from other customers of theirs that are directly connected to them. They would prefer that traffic to remain on their direct connection to you and may be ignoring any community or pre-pend you are sending out. You must escalate and work through sales channel if you have to. Tell you get responses back from them you are just guessing and hoping for the best....

[Elie_Raad]

Guys, i have had a case open with Expedient and Cognet for almost a Year and ISPs are hard to deal with and it takes forever. i am trying to implement a Solution from my side . in my initial post i mentioned if someone know if there is a feature like bgp advertise-map as in cisco.
thank you ,

[Elie_Raad]

what if the primary link fails to the other ISP . how will the secondary ISP knows that so that their routers can remove these communities