BGP config WAS RE: [c-nsp] internet redundancy [7:99340]

[Kern, Tom]

as it stands right now, my current config is as such-



internet router----firewall------L3switch(cat 4500)------router-----T1---------albany router-------firewall----internet router





I'm just using an exanmple of my config with 2 sites(NYC and Albany). There is a third site(Buffalo) with its own internet connection and i T1 to Albany and a seperate t1 to NYC. I just left it out for clarity.


All these routers(except the internet one's) run eigrp. As it stands now, there is a static default route on the L3 switch pointing to the NYC internet router.
This static route is redistributed into eigrp to the other sites. so right now, the other sites use NYC internet as the gateway of last resort.


I just wanted to give a slightky clearer view of my set up before proceedeing with Dave's advice.

Is anything wrong here right now as it stands?

Also, will most isp's play "nice" with each other for this?
will they charge me an extra fee?

thanks a lot for all your help so far.
you guys have been great!


David Barak wrote:
> in-line.
> 
> --- Vikas Sharma  wrote:
> 
>> Hi,
>>  1) You don't need to pay for using ASN as this is
>> default BGP attribute.
> 
> the fact than an ASN is a default attribute has
> nothing whatsoever to do with payment.  In any case,
> Tom will need to contact a RIR (ARIN, RIPE, etc) and
> obtain a public ASN, and for this, he'll have to pay a
> nominal annual fee.
> 
> 
>> 2) It is better if u use IBGP internally because
>> IBGP support all attribute
>> of BGP and one should avoid redistribution as
>> possible.
>> 3) You need your ASN only when u want to differ from ISP policies
>> otherwise u don't require ASN.
> 
> Tom is connecting to multiple ISPs - therefore, BGP is
> the appropriate solution.
> 
> 
>> 4) To filter you can use
>>  a) Prefix filtering
>>  b) AS_path filtering
>>  c) Route map fltering
>>  d) Community filtering
> 
> The most effective type of filtering in this case is
> done on the provider's routers - just ask the provider
> for their networks and their customer networks, and
> all will be well.
> 
>>  beside this u need to ask ur SP's to broadcast
>> other SP's route in their
>> network or u may not need this if BGP
>> synchronization is enable in all SPs.
> 
> No service provider worth their salt uses BGP
> synchronization.  If they did, they would only
> advertise routes which appeared in their IGP!  Rather,
> if Tom's ISPs are all cooperative, then they will
> permit him to originate address space, and will carry
> those announcements rather than aggregating them.
> 
>>  Chad :- here internet router and core router are
>> different. so no need to
>> think abt internet link go down as these are
>> seperate router. Redistribution
>> of default route is a good option with network
>> 0.0.0.0  in
>> bgp, but if that link is down there will not be any connectivity.
>> You can also use MED attribute to specify the best route.
> 
> ick!  Redistribution of a default route is an ugly
> solution: the better approach is to have the edge
> routers all speak iBGP with each other and the core
> routers which make decisions.  The core routers are
> the default gateways for Tom's internal network, and
> once data reaches the core, it follows a BGP path
> outward.
> 
> 
> -David Barak
> 
> 
> David Barak
> Need Geek Rock?  Try The Franchise:
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> 
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