Probe on a /31 or /32 IPv4 network
Hi, We would like to deploy our Atlas probe on a separate L2 network, but without having to spend 4 IPv4 addresses (i.e. a /30 network). Using a /31 would be nice, but the web UI doesn't allow it as static IPv4 configuration ("The Gateway address should be different from the ending network address"). Would it be possible to allow /31 in the web UI? I believe the probes themselves support it. Even nicer would be support for /32 networks, even though it is perhaps less usual. This can easily be done with iproute2 on Linux, assuming the probe is 192.0.2.48/32 and its gateway is 192.0.2.1: ip addr add 192.0.2.48/32 dev eth0 ip route add 192.0.2.1/32 dev eth0 ip route add default via 192.0.2.1 or even shorter: ip addr add 192.0.2.48/32 dev eth0 ip route add default via 192.0.2.1 onlink dev eth0 Using a gateway that is not on the same subnet doesn't sound very nice, but again, the goal is to avoid wasting precious IPv4 space. Thanks, Baptiste
On 2014/08/14 23:15 , Baptiste Jonglez wrote:
Even nicer would be support for /32 networks, even though it is perhaps less usual. This can easily be done with iproute2 on Linux, assuming the probe is 192.0.2.48/32 and its gateway is 192.0.2.1:
Why not just fool the probe and tell it is on a /24? Philip
On Thu, 14 Aug 2014, Baptiste Jonglez wrote:
Using a gateway that is not on the same subnet doesn't sound very nice, but again, the goal is to avoid wasting precious IPv4 space.
What router platform are you using upstream from the probe? Doing a /32 per vlan(ie sharing a larger subnet between different vlans) is perfectly possible on several routing platforms. http://tools.ietf.org/html/rfc3069.html You can do this with Ciscos using static /32 route pointing to a vlan. http://www.gossamer-threads.com/lists/nsp/ipv6/25933 -- Mikael Abrahamsson email: swmike@swm.pp.se
On Fri, Aug 15, 2014 at 06:23:09AM +0200, Mikael Abrahamsson wrote:
On Thu, 14 Aug 2014, Baptiste Jonglez wrote:
Using a gateway that is not on the same subnet doesn't sound very nice, but again, the goal is to avoid wasting precious IPv4 space.
What router platform are you using upstream from the probe? Doing a /32 per vlan(ie sharing a larger subnet between different vlans) is perfectly possible on several routing platforms.
We're using Linux. Actually, we are already routing a /32 per VLAN on the router, but up to now, we were also setting up /32 "subnets" on the downstream routers or hosts.
Interesting read. It basically amounts to use /32 routes on the router, and a larger subnet (e.g. /24) on hosts, as Philip suggests. This is a bit of a hack when hosts want to talk to each other, but this is mostly ok for the probe (or we can use proxy ARP on the router if it becomes a problem). Thanks for the help, Baptiste
"(or we can use proxy ARP on the router if it becomes a problem)." You're a braver man than I. Personally, the prospect of troubleshooting proxy-arp at 3 am doesn't sound like much fun. -James -----Original Message----- From: ripe-atlas-bounces@ripe.net [mailto:ripe-atlas-bounces@ripe.net] On Behalf Of Baptiste Jonglez Sent: Friday, August 15, 2014 12:07 AM To: ripe-atlas@ripe.net Subject: Re: [atlas] Probe on a /31 or /32 IPv4 network On Fri, Aug 15, 2014 at 06:23:09AM +0200, Mikael Abrahamsson wrote:
On Thu, 14 Aug 2014, Baptiste Jonglez wrote:
Using a gateway that is not on the same subnet doesn't sound very nice, but again, the goal is to avoid wasting precious IPv4 space.
What router platform are you using upstream from the probe? Doing a /32 per vlan(ie sharing a larger subnet between different vlans) is perfectly possible on several routing platforms.
We're using Linux. Actually, we are already routing a /32 per VLAN on the router, but up to now, we were also setting up /32 "subnets" on the downstream routers or hosts.
Interesting read. It basically amounts to use /32 routes on the router, and a larger subnet (e.g. /24) on hosts, as Philip suggests. This is a bit of a hack when hosts want to talk to each other, but this is mostly ok for the probe (or we can use proxy ARP on the router if it becomes a problem). Thanks for the help, Baptiste
participants (4)
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Baptiste Jonglez -
James Sink -
Mikael Abrahamsson -
Philip Homburg