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From: Benjamin Black <b@b3k.us>
Date: Wed, 1 Sep 2010 15:10:43 -0700
Message-ID: <AANLkTikH2+AJ3V24zKmqpaa7yBiTe_yq7yWdm6tj1mvu@mail.gmail.com>
Subject: Re: Cassandra on AWS across Regions
To: Andres March <amarch@qualcomm.com>
Cc: "user@cassandra.apache.org" <user@cassandra.apache.org>
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It's not gossiping hostnames, it's gossiping IP addresses.  The
purpose of Peter's patch is to have the system gossip its external
address (so other nodes can connect), but bind its internal address.
As Edward notes, it helps with NAT in general, not just EC2.  Not
perfect, but a great start.


b

On Wed, Sep 1, 2010 at 2:57 PM, Andres March <amarch@qualcomm.com> wrote:
> Is it not possible to put the external host name in cassandra.yaml and ad=
d a
> host entry in /etc/hosts for that name to resolve to the local interface?
>
> On 09/01/2010 01:24 PM, Benjamin Black wrote:
>
> The issue is this:
>
> The IP address by which an EC2 instance is known _externally_ is not
> actually on the instance itself (the address being translated), and
> the _internal_ address is not accessible across regions.  Since you
> can't bind a specific address that is not on one of your local
> interfaces, and Cassandra nodes don't have a notion of internal vs
> external you need a mechanism by which a node is told to bind one IP
> (the internal one), while it gossips another (the external one).
>
> I like what this patch does conceptually, but would prefer
> configuration options to cause it to happen (obviously a much larger
> patch).  Very cool, Peter!
>
>
> b
>
> On Wed, Sep 1, 2010 at 1:10 PM, Andres March <amarch@qualcomm.com> wrote:
>
> Could you explain this point further?=A0 Was there an exception?
>
> On 09/01/2010 09:26 AM, Peter Fales wrote:
>
> that doesn't quite work with the stock Cassandra, as it will
> try to bind and listen on those addresses and give up because they
> don't appear to be valid network addresses.
>
> --
> Andres March
> amarch@qualcomm.com
> Qualcomm Internet Services
>
> --
> Andres March
> amarch@qualcomm.com
> Qualcomm Internet Services