This is entirely up to you since you'll be doing the configuration. If
you choose to configure the AT&T link as backup only, then you'll only
have 3MB available. Do you already have at least a full /24 prefix
assigned to you? Do you have your own ASN?
If so, then if you have a hefty enough router, accept customer-only
routes from all three links and let the router choose the best link.
Since you'll have two links to Qwest, this will require more thought
since the AS Path will be the same. You'll have to consider using other
attributes to make your routing decisions.
If you really have a beefy router you could accept full routes from all
three locations. Again, having two links to Qwest makes intelligent
routing more difficult. In this situation, here's how I would do it:
1. Accept customer only routes from AT&T
2. Accept at least the default from the two Qwest links, possibly
customer-only routes
3. Let the router make the best decision between either an AT&T exit or
a Qwest exit.
4. For prefixes that are closer through Qwest, do per-destination
load-sharing on the Qwest links.
To make this simpler, basically if your router learns a route from the
AT&T link it will always use that link for that prefix. If it doesn't
have an explicit route then load-share over the Qwest links.
But, that's how I would do it. You should get some other opinions and
then compare them with your goals to figure out what's best for you.
HTH,
John
>>> "Jeongwoo Park" 7/25/01 5:24:42 PM >>>
Hi all
I am trying to implement BGP.
I used to have 2T1 lines going straight to Qwest (isp). Now I want to
install another T1 line going to AT&T (isp) as a back-up line.
Now my question is what bandwidth will I have?
Will I have 4.5M bandwidth (2xT1 + T1) together? or Will I have only
3M
bandwidth (2xT1) from Qwest because T1 going to AT&T is used as a
back-up?
It would be better if I could use extra T1 not only as a back up but
also as
an additional bandwidth.
Your input will be appreciated.
JP
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