14 Jun
2015
14 Jun
'15
11:45 p.m.
On Sun, Jun 14, 2015 at 08:44:05PM -0700, Tim Osburn wrote:
Brian,
I've updated the drawing in response to your private email you sent
to me. Would it be possible to "add" a shim box between the telescope
project and your amprgw server? I think we could still achieve what
we're trying to do if that is something you can do.
What you seem to suggest would be to put the SHIM essentially in series
with the telescope and have amprgw forward all outbound 44/8 traffic to
the SHIM - where some of it would be encapsulated to the various tunnel
gateways. If I understand what you're proposing, the traffic to the
BGP-routed 44 subnets would travel from the SHIM over the GRE tunnel
to the ISPs who would then route it appropriately. All inbound 44/8
traffic which didn't pass the filters would be routed to the telescope.
This requires that TWO boxes know about the gateway subnets, as well as
having the SHIM learn about the BGP-routed subnets via BGP from the ISP
over the GRE tunnel. This seems needlessly complex. It also means that
all telescope data has to pass through the SHIM box, which could tax an
underpowered box. (I'm not familiar with the SHIM box itself.)
A year or more ago we discussed a scheme where each BGP-routed subnet
would simply register a route in the gateways table that pointed
to a cooperating router (off the UCSD network) which was capable of
decapsulating the tunneled packets and routing them appropriately.
This has two advantages: it doesn't require any additional hardware
and it doesn't require any changes in the UCSD gateway or network.
I don't know how hard it would be to set up a general decapsulator in
an existing router, but if it's not too difficult this is a simple step
to get where we want to go, don't you think? True, it means that each new
BGP subnet would have to register a single entry in the portal, but I
don't see that as a hassle. What do you think of this alternative?
RE: "advertise /24 summary routes" The only
downside to off loading
the IPIP tunnels to a ISP is that the telescope project will lose
out on some traffic. Example; if a /30 or /32 has been allocated out
of a /24 CIDR then the ISP would need to advertise the whole /24 just
for that one small tiny use case. Where as if you add the shim box
then all the traffic outside the allocated space in that /24 would
pass onto the telescope making for better research data.
In the grand scheme of things, even rounded up to /24s, the total
allocated ham radio space is miniscule compared to the unallocated space
anyway. I think the researchers already factor this in.
I also see the number of tunnel gateways decreasing in future.
- Brian