nanog mailing list archives

Re: asymmetric routes/security concerns/Fortinet


From: Greg Whynott <Greg.Whynott () oicr on ca>
Date: Fri, 7 Jan 2011 13:56:00 -0500

Thanks John for your input.

You are correct,  ORION is a dedicated high speed research network.

Based on the fact that we access ORION via one of our ISPs (3rd party,  we don't  BGP/directly peer with ORION),  I'm 
not sure if i can use this solution here.   I could do that for the routes learned from that ISP,  but we receive the 
entire internet routing table from them…  I'd have to understand things more before I went down that road.  perhaps I 
shouldn't be accepting the full table from them.

the localpref is something I'll look at,  thanks for that.   I'm not a BGP expert by any stretch,  and our requirements 
here are "simple".  we are not a transit.    I've only attempted to make the config safe,  not efficient.


 i'd like to hear what you have to say about the original question,  is there good reason in this day and age to drop 
traffic as described in the original post in your opinion?

-g



On Jan 7, 2011, at 1:15 PM, John Kristoff wrote:

On Fri, 7 Jan 2011 12:40:32 -0500
Greg Whynott <Greg.Whynott () oicr on ca> wrote:

we have multiple internet connections of which one is a research
network where many medical institutions and universities are also
connected to threw out the country.  This research network (ORION)
also has internet access but is not meant to be used as a primary
path to the internet by its customers.     Connected to the ORION
network are many sites we exchange email with daily who also have
multiple internet connections.   One of these sites is not reachable
by us.   After investigating,  it was discovered this site is
dropping our connections as the path back to use would use a
different interface on the firewall ( a Fortinet device) than that
which it arrived upon.

Correct me if I'm wrong, I'm not very familiar with ORION, but if it's
like some of the research networks in the U.S. have been built in the
past, ORION is dedicated high speed, low latency network that
interconnects research institutions together.  The way these are often
used is that you localpref routes you learn from ORION participants so
that traffic between each of you goes over the research network.  You'd
typically want this since the performance is good and there is plenty of
capacity available, but it is also paid for, probably through some
research grant, helping to reduce the use and expense of your commercial
transit.

You should be sending your traffic to them via ORION and they
likewise.  However, if that path is down, then it would make sense for
it to go via another route.  Hence, asymmetry may happen.

Are you not sending the traffic via ORION?  If so, then I'd suggest you
both have something to fix.  :-)

John


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