BGP advertise-map in XOS
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‎06-20-2017 11:05 AM
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
Is there a way of doing it in XOS ?
Thank You,
Elie
29 REPLIES 29
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‎06-20-2017 12:24 PM
Yes, e.g. if you announce your prefixes to as20850 with community 20850:50 -- they will accept your announce and change localpref to 50
Please see https://apps.db.ripe.net/search/lookup.html?source=ripe&key=AS20850&type=aut-num
Please see https://apps.db.ripe.net/search/lookup.html?source=ripe&key=AS20850&type=aut-num
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‎06-20-2017 12:24 PM
You mean: upstream can accept BGP community that will change localpref for your prefix  ?
--
Jarek
--
Jarek
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‎06-20-2017 12:24 PM
Jarek, that's the point I'm trying to explain
Or your upstream can manually accept your prefixes with a different localpref if you ask them to do that.
Or your upstream can manually accept your prefixes with a different localpref if you ask them to do that.
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‎06-20-2017 12:24 PM
Nick,
please see RFC4277 (https://tools.ietf.org/html/rfc4277)
Page 6 says:
BGP has a separate metric parameter for IBGP and EBGP. This allows policy-based metrics to overwrite the distance-based metrics; this allows each autonomous system to define its independent policies in Intra-AS, as well as Inter-AS. BGP Multi Exit Discriminator (MED) is used as a metric by EBGP peers (i.e., inter- domain), while Local Preference (LOCAL_PREF) is used by IBGP peers (i.e., intra-domain) ... and so on...
As a customer you can't add localpref direct in your ISP/Upstream/Transit AS.
Your ISP/Upstream/Transit can configure for customers on their own router/routers BGP community that you could use to change localpref for your prefix/prefixes in their AS.
--
Jarek
please see RFC4277 (https://tools.ietf.org/html/rfc4277)
Page 6 says:
BGP has a separate metric parameter for IBGP and EBGP. This allows policy-based metrics to overwrite the distance-based metrics; this allows each autonomous system to define its independent policies in Intra-AS, as well as Inter-AS. BGP Multi Exit Discriminator (MED) is used as a metric by EBGP peers (i.e., inter- domain), while Local Preference (LOCAL_PREF) is used by IBGP peers (i.e., intra-domain) ... and so on...
As a customer you can't add localpref direct in your ISP/Upstream/Transit AS.
Your ISP/Upstream/Transit can configure for customers on their own router/routers BGP community that you could use to change localpref for your prefix/prefixes in their AS.
--
Jarek
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‎06-20-2017 12:24 PM
I do not agree with you:
If an ISP gets all prefix announces from their uplinks with, say, localpref 100, and from a specific customer on a direct link they get prefix announces with 50, then direct announce will become active only if their prefix will become invisible from their uplinks
If an ISP gets all prefix announces from their uplinks with, say, localpref 100, and from a specific customer on a direct link they get prefix announces with 50, then direct announce will become active only if their prefix will become invisible from their uplinks
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