Most isp's are going to be picky about advertising such a small subnet.
Luckily, all is not lost. You'll have to get a /24 from one of your Isp's
to get the best shot at being Globally Routable. Also, you have to get an AS
# from ARIN, But before you spend the time (money) to do it, make sure (in
writing) that you can get the Ip's and ISP1 and ISP2 will both advertise
you. If not, find different ISP's. (Unrelated question to group: Are
there any provider-independent /24's left?)
Your BGP setup doesn't have to be complicated, Just accept the directly
connected BGP routes and discard the rest. Only advertise the route to your
/24 (No subnetworks, No Flapping).
Good Luck,
Ejay
----Original Message Follows----
From: John Neiberger <[EMAIL PROTECTED]>
Reply-To: John Neiberger <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: BGP, Multihoming, and Me
Date: Fri, 13 Oct 2000 07:35:35 -0700 (PDT)
I have a question that I'm sure has been referenced before but I couldn't
find an answer in the archives, and it's more practical than technical.
We have a single T-1 connection to an ISP for customer access to our
internal webservers so that our banking customers can do web-based
transactions and get account information. This is such an important aspect
of our business that we decided to get a second T-1 to another ISP for
redundancy. We aren't as concerned with being able to load-balance, which
is a dicey prospect in this arrangement anyway.
Now, the problem: we have a tiny subnet assigned to us from ISP-1, it's a
/27. Now let's say we get a connection to ISP-2 and we start running BGP.
Is ISP-2 probably going to have a problem letting us advertise such a small
set of routes? I've been hearing that big ISPs tend not to want to
advertise subnets smaller than a /18. If that's the case, our plan is in
trouble.
Now, problem #2: even if we can advertise a /27 through ISP-2, ISP-1 is
going to have to agree to advertise our /27 along with their aggregate
advertisement. If they don't, and they only advertise their aggregate, this
will cause return traffic to our network to come through ISP-2 because it
will be advertising a more specific route, correct? If that's correct, do
ISPs tend to have a problem with this arrangement?
Basically, are we setting ourselves up for disappointment? Are there any
other factors that I should be aware of that I'm not considering? Should I
become a yak herder and move to Nepal?
Thanks, as usual...
John Neiberger
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