Gino,
You may need to look at the routes that are advertised via a looking glass
to discover the reason. For example use the looking glass of your provider,
and that of the other upstreams of the customer.
As well, look at the customer's BGP tables.
First define, are the configured advertisement actually advertizing from the
customer. Configuration errors can sometimes prevent that. For example...
A) if a rule was manually added to a text file of Quagga out of
place.
B) Routemap and filter relationships are not right.
Second, Confirm all upstreams will accept all the route advertizements.
Many reasons they might not....
A) Advertising a smaller subblock within a larger allocated registered
block. Some providers do not allow it. Upstreams would need to add "le 24"
if adverrising a /24 on a /22.
B) Reached max limit of allowable routes to advertise. Upstream must
increase limit.
C) Upstream may be filtering the IPs advertising, if they were not made
aware of it.
D) RIR records have not been updated to reflect your route policy, some
upstreams filter on RIR records.
E) Upstream does not accept small blocks below a certain size
Third, Confirm routes aren' being overided at upstream
A) A static route exists on the upstream to override.
B) Some upstream BGP netwrok designs have routers that do not have
enough memory for Full tables, and therefore all advertised routes may not
exist on all routers, causing path issues. Smallest blocks will usually drop
out first.
C) Both Customer Upstream have a next hop Common upstream, and have
rules for passing traffic between them that overide your advertised route.
I can give an example of a common issue... Lets say we have a
registered /22, and want to advertise a /24 at peerA and a /24 at peerB. We
might Advertise a /22 at both, in case the route is not accepted by one of
the upstream's upstreams because it is small block, as a safety measure. We
might AS prepend PeerB over A to make one more priority for the /22 block.
So both the /24 and /22 will advertise to a peer. Now lets say the /24
advertisement gets dropped because a router has no memory for it, or what
ever reason, the /22 may still exist, causing a different routing behavior
than configured for the /24. .
Fourth, Make sure that your network being the return path, is not blocking
the IPs from returning because of your own internal OSPF / IBGP rules.
I guess my point is.... Without having any detail, or narrowing it down, the
number of possibilties are endless to why it is not working.
If you can verify what advertised routes propogated to what upstreams, you
can then determine what factors might have led to that result.
Lastly, I'll mention AS Prepend is often a default first choice for
prioritizing the inbound route. But that method is not all or nothing for an
advertisement. We found that for our customers, if they wanted a block to
return on our circuit, they wanted all traffic on that block to return on
out network. They wanted it 100%. One way to do that is to combine route
maps with shortest block advertisements. For example, You onl;y advertise
the /24 A on PeerA and /24 B on PeerB, so there is onl;y one configured
choice for each /24. Then advertise the /22 for only one peers, or Prepend
the /22 to propritize it. That mentality may not scale across having a
large number of peers and upstreams, but for an end user customer with 2-3
Transits, it works well. We found that trobuleshooting customers was to
hard UNLESS we knew and the customer knew what traffic was going across our
network. With AS PRepending, maybe some of hte traffic might cross the other
path in some situations. Everytime a customer has a slow access to a
destination site, we havce to check BGP routes or firewalls snifffing before
troubleshooting to know if its our problem or not.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: "Gino Villarini" <[email protected]>
To: "WISPA General List" <[email protected]>
Sent: Tuesday, June 09, 2009 3:09 PM
Subject: Re: [WISPA] Need BGP Support ASAP
> Exactly,
>
> The problem is not for own ip space, its for a downstream customer ips
> space, they have several providers and want to favor our link for some
> ip ranges. They are prepending such ranges to the other providers to
> favor our link.
>
>
> Gino A. Villarini
> [email protected]
> Aeronet Wireless Broadband Corp.
> tel 787.273.4143 fax 787.273.4145
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of David
> Sent: Tuesday, June 09, 2009 3:02 PM
> To: 'WISPA General List'
> Subject: Re: [WISPA] Need BGP Support ASAP
>
> You prepend the link you want to disfavor. The more you prepend the
> longer a route will look.
>
> David
>
>> -----Original Message-----
>> From: [email protected] [mailto:[email protected]]
>> On Behalf Of Gino Villarini
>> Sent: Tuesday, June 09, 2009 12:57 PM
>> To: WISPA General List; [email protected]
>> Subject: Re: [WISPA] Need BGP Support ASAP
>>
>> Should I not prepend to favor our link?
>>
>>
>> Gino A. Villarini
>> [email protected]
>> Aeronet Wireless Broadband Corp.
>> tel 787.273.4143 fax 787.273.4145
>>
>> -----Original Message-----
>> From: [email protected] [mailto:[email protected]]
>> On Behalf Of Michael Baird
>> Sent: Tuesday, June 09, 2009 2:52 PM
>> To: [email protected]; WISPA General List
>> Subject: Re: [WISPA] Need BGP Support ASAP
>>
>> You mean prepending AS numbers, not routes. Prepending will also
>> lengthen the the calculation, so if they are prepending to you, this
>> would the route through your link less favorable to the outside world.
>>
>> Are you seeing the prepend coming from their routers? On a cisco it
>> would be show ip neighbor <ipaddress> received-routes, if you are
>> seeing the prepend from them, check and see if you are forwarding them
>
>> on to your upstream show ip neighbor <ipaddress of upstream interface>
>
>> advertised-routes. If you see these in both places, it's most likely
>> your upstream not allowing the prepend.
>>
>> Regards
>> Michael Baird
>> > Did you notify your upstream that you be advertising your customers
>> routes?
>> >
>> > On Tue, Jun 9, 2009 at 2:24 PM, Jeff Broadwick<[email protected]>
>> wrote:
>> >
>> >> I recommend Tony Mattke for dynamic routing work.
>> >>
>> >> [email protected]
>> >>
>> >> Regards,
>> >>
>> >> Jeff
>> >>
>> >> -----Original Message-----
>> >> From: [email protected]
>> >> [mailto:[email protected]]
>> >> On Behalf Of Gino Villarini
>> >> Sent: Tuesday, June 09, 2009 2:22 PM
>> >> To: WISPA General List
>> >> Subject: [WISPA] Need BGP Support ASAP
>> >>
>> >> Anyone available for some BGP support?
>> >>
>> >> Im providing Internet service to another ISP, they are prepending
>> >> some routes to favor our link, still my router doesnt acknoledge it
>> >>
>> >>
>> >> Gino A. Villarini
>> >> [email protected]
>> >> Aeronet Wireless Broadband Corp.
>> >> tel 787.273.4143 fax 787.273.4145
>> >>
>> >>
>> >>
>> >>
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