Regular expressions usage in BGP

[Mikey John]

Hi,

I have a new spoke site coming up with MPLS as primary and Metro E as backup. Both spoke site and Hub site use the same MPLS Service provider XYZ

Spoke site setup (New)
=================

MPLS - XYZ
Metro E as backup to Hub site (same city) - Proposed eBGP to Hub site over Metro E, and then out via MPLS XYZ

Hub Site setup (Existing)
=========================

MPLS - XYZ

Hub router has route-map installed on BGP which states that only Locally originated routes should go out to XYZ MPLS cloud (using Regex ^$)

Now, looking at the new spoke site, if Primary MPLS link fails, and the traffic flows from Spoke site->Hub site over eBGP, it will not go out via XYZ MPLS cloud in hub site because it allows only locally originated routes to go out.

Question

1) Using Regex, how do I make the hub site router to allow the routes locally originated routes + the routes originated in spoke site to go out its XYZ MPLS cloud.

2) For inbound routing to spoke site (if primary MPLS links is UP), the path preferred would be via teh YZ MPLS cloud in spoke site router owing to AS-path? Or would it be via hub site? Or asymmetrical?

Thanks

Mikey

[Mikey John]

Appreciate if someone could help here.

Cheers

Mikey

[Mikey John]

Hey guys,

 Appreciate  some pointers out here.

Cheers

[Jon Marshall]

Can you clarify the AS numbers being used ?

Jon

[Mikey John]

AS100 for hub site, and AS200 for spoke site.

Cheers

Mikey

[Jon Marshall]

Sorry I have should have been more specific. 

Do you have other spokes and if so do you not want the hub to be backup for them ? 

I am trying to work out whether you just need a different regex or you can just remove it and let the hub site advertise out all BGP routes but just make sure the hub is only used for the spoke site(s) if the main spoke site MPLS connection fails.

Jon

[Jon Marshall]

Also if there are other spokes is each spoke using a different AS number ?

Jon

[paul driver]

Hello Mikey/Jon

1) Using Regex, how do I make the hub site router to allow the routes locally originated routes + the routes originated in spoke site to go out its XYZ MPLS cloud.

ip as-path access-list x permit ^$  <-- i am assuming this is the existing as-path statement for originated routes

so let say you new spoke site has a ASN10

ip as-path access-list 1 permit _10$  <---- allow for prefix that originated for asn10

2) For inbound routing to spoke site (if primary MPLS links is UP), the path preferred would be via teh YZ MPLS cloud in spoke site router owing to AS-path? Or would it be via hub site? Or asymmetrical?

inbound it would take the spoke site as the hub site would be adverting longer as-path in it routes it received from the spoke.

res
Paul