Re: Routing comment

[Jan-Erik Eriksson <]

On Wed, 6 Sep 2000, Tony Barber wrote:

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

Even worse, you don't know if it actually is a link problem or
"just" an ethernet problem when the link takes a dive into to the deep
blue...

Use numbered links, or addresses from a loopback if you must use
unnumbered links. 

>
>
>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
>>
>> Disclaimer
>> ----------
>> This email and any files transmitted with it are confidential and are
>> intended solely for the use of the individual or entity to whom they are
>> addressed. This communication represents the originator's personal views and
>> opinions, which do not necessarily reflect those of the NSC Group. If you
>> are not the original recipient or the person responsible for delivering the
>> email to the intended recipient, be advised that you have received this
>> email in error, and that any use, dissemination, forwarding, printing, or
>> copying of this email is strictly prohibited. If you received this email in
>> error, please immediately notify administrator@localhost.
>

------------- Elcom ------------- Network Operations Center ---------
Jan-Erik Eriksson		mailto: jee@localhost
Elcom				phone: +358 18 23500
PB 233, Torggatan 10		fax: +358 18 14643
FIN-22100 Mariehamn		URL: http://www.alcom.aland.fi