Thanks, I appreciate your comments.
Zsombor
At 01:36 PM 6/23/2003 -0500, MADMAN wrote:
> Were the two T1's terminating at two differant ISP's? If so BGP
>would be appropriate. If you have 2 T1's terminating at a single ISP in
>the same POP then no.
What would you do if they had been terminating at a single ISP in the
same POP? Or did you mean "same router"?
>>>
>>>
>>> Most likely simple default routes.
>>
>>You mean default static routes? From a pure theoretical point of view,
>>that seems a bit dangerous to me (to have two default static route
>>pointing to two different routers). If one of the ISP routers is not
>>directly connected to the customer's router (because for example there is
>>an Ethernet switch in the middle), then the customer's router won't
>>notice even if the ISP router is powered down. Even if the two routers
>>are directly connected, it is possible (even though with current IOS
>>versions it is not very likely) that the interface stays up even though
>>routing dies on the ISP router. In short, I think there is a chance of
>>you blackholing half of your traffic.
>>Comments? :)
>>Thanks,
>>Zsombor
>
> Unless your co-located with your ISP your probably not connected to an
> ethernet switch! Though even if serially connected, with static routes
> you would not know if the LAN connection on the ISP router went down
> effectively causing the same blackholing you refer to.
>
> Like most things there is a cost/benefit analysis. WAN links are more
> prone to outages than the LAN, pointing your default to the ISP WAN is
> simple and commonly used config. For cusomters that are more sensitive
> to outages may opt for dual homing to 2 ISP's using ful routing and have
> their WAN connections via a SHNS or SHARP configuration.
>
> Redundancy and simplicity are not bedfellows and the more your willing
> to spend the more redundancy can be had.
>
> Dave
>
>>
>>> Though as Howard alluded to there are some exceptions where you may
>>> use BGP but not to recieve full routing but more likely to control
>>> network announcements. You could exchange same router/POP as far as
>>> routing is concerned.
>>>
>>> Dave
>
>
>--
>David Madland
>CCIE# 2016
>Sr. Network Engineer
>Qwest Communications
>612-664-3367
>
>"Government can do something for the people only in proportion as it
>can do something to the people." -- Thomas Jefferson
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