Re: Routing comment

[Tony Barber <]

Ah yes, creating a NOC alarm every time the caretaker switches the hub off ;-)


tb



Morgan Dollard wrote:

> Hello,
> In reading the IOS Essentials for ISP's PDF, ver 2.84
>  http://www.cisco.com/public/cons/isp/documents/IOSEssentialsPDF.zip
>
>  i came across something I believe might need a little bit of clarification.
>
> I dont know if many ISP's use this method or not, but i find it particularly
> usefull.
>
> On page 29, under the Caveats section, specifically the routing protocols
> part, it is stated that :
> ". Routing Protocols. If a routing protocol needs to be run over this link,
> it is operationally much easier to use IP
> addresses. Don't use "ip unnumbered" if the customer is peering with you
> using BGP across the link, or if the link is
> an internal backbone link. Simply use a network with a /30 address mask.
> (Routing will work over unnumbered links
> but the extra management and operational complexity probably outweighs the
> small address space advantage gained.) "
>
> Using Ip unnumbered and BGP is something that works extremely well, in the
> following case.
>  The wan interface is unnumbered to the ethernet interface. The ethernet
> interface is using a primary IP that is the one that should be configured on
> the WAN interface, and a secondary IP that is the LAN IP
>
> In most cases, the Provider will want to peer its BGP session to the IP it
> assigned the customer. This setup allows the BGP session to be peered to the
> Ethernet interface, which in turns leeds to an end to end point of failure,
> from the Ethernet Interface, to the Wan Interface. This succesfully allows
> the ISP to monitor the customer's network availability without the use of
> piningin methods, and relying solely upon the well being of the BGP session.
>
> If this message is off list topic, i apologize for the inconvenience.
>
> Morgan Dollard
>
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