On some gear, it will ARP for an address that is not directly connected
when you force the interface being used.
(Basically telling the router "Ignore the forwarding table...use this
interface no matter what").
To which the router says "okay, but i'm gonna have to ARP for it, and
anyone watching is going to think I don't know what i'm doing...."
(And they'd be correct...)
Under normal circumstances (not specifying the interface), my traceroutes
happily go out the shortest transit path shown in the full BGP feed.
No proxy arp here. :)
~Matthew
On Thu, Aug 16, 2018 at 5:13 PM, Andrew Hoyos <[log in to unmask]> wrote:
> Yeah, was just writing this.
> Your router should see that it’s not a directly connected IP, and back up
> to routing table/FIB. It may ARP for next hop depending on path.
>
> For those with this issue, what say your routing tables for this subnet?
> And do *you* have proxy arp turned off?
>
> —
> Andrew Hoyos
> [log in to unmask]
>
>
>
> On Aug 16, 2018, at 3:11 PM, Jeremy Lumby <[log in to unmask]> wrote:
>
> Why would your router ARP for an address that is not on the same subnet as
> any of your interfaces?
>
> *From:* MICE Discuss [mailto:[log in to unmask]
> <[log in to unmask]>] *On Behalf Of *Matthew Beckwell
> *Sent:* Thursday, August 16, 2018 5:01 PM
> *To:* [log in to unmask]
> *Subject:* Re: [MICE-DISCUSS] Routing of non-IX traffic
>
> I'm getting similar behavior as Frank.
>
> Like Doug, I only have 45.60.73.0/24 from transit connections.
> So a traceroute from my MICE interface should ARP and die (I would
> think)....
>
> When I traceroute to 45.60.73.16-- my router sends out an ARP request, as
> expected.
> But...I get ARP replies for 45.60.73.16 from these Cisco MACs (in the
> order they came into my interface):
>
>
> 00:23:33:c6:a0:c0
> 206.108.255.50
> Cooperative Network Services (CNS)
> 32609
> e4:aa:5d:83:73:06
> 206.108.255.47
> IVDesk
> 393639
> 88:43:e1:00:f2:10
> 206.108.255.18
> Consolidated Communications
> 12042
> b0:aa:77:33:7b:03
> 206.108.255.79
> Gigamonster, LLC
> 31939
> 3c:08:f6:81:6e:a5
> 206.108.255.46
> OneNetUSA
> 46131
> 00:1d:e5:c0:78:c3
> 206.108.255.5
> Implex
> 21709
> 54:75:d0:e6:08:30
> 206.108.255.106
> Nuvera Communications
> 23465
> 00:11:5d:82:6c:00
> 206.108.255.80
> Future Technologies
> 26451
>
>
> Proxy ARP (or something like it)?
> CNS seems to be consistently coming in first place when I clear my ARP
> entry.
>
> ~Matthew
> [log in to unmask]
> AS13746
>
>
>
>
> On Thu, Aug 16, 2018 at 3:25 PM, Frank Bulk <[log in to unmask]>
> wrote:
> When I force a traceroute to originate from our MICE-facing connection,
> the first hop is 206.108.255.50 (AS32609 aka CNS). Any reason why?
>
> To making things more interesting, Incapsula-destined traffic goes via
> Paul Bunyan. Here's just one example:
>
> traceroute to www.yamaha-dealers.com (45.60.73.16), 30 hops max, 60 byte
> packets
> 1 AS32609.micemn.net (206.108.255.50)
> 14.059 ms 14.084 ms 14.076 ms
> 2 cns70.cnsllc.net (205.149.150.9) 18.484 ms 18.434 ms 18.507 ms
> 3 fg30.ips.cnsllc.net (205.149.150.30) 20.254 ms 20.346 ms 20.267 ms
> 4 crss2.PaulBunyan.net (205.149.159.197)
> 20.527 ms 20.562 ms 20.619 ms
> 5 cra.PaulBunyan.net (205.149.159.181)
> 23.398 ms fp233.ips.PaulBunyan.net (205.149.159.233)
> 22.669 ms cra.PaulBunyan.net (205.149.159.181)
> 23.393 ms
> 6 * * *
> 7 * * *
> 8 * * *
> 9 * * *
> 10 * * *
> 11 * * *
> 12 * * *
> 13 * * *
> 14 * * *
> 15 * * *
> 16 * * *
> 17 * * *
> 18 * * *
> 19 * * *
> 20 * * *
> 21 * * *
> 22 * * *
> 23 * * *
> 24 * * *
> 25 * * *
> 26 * * *
> 27 * * *
> 28 * * *
> 29 * * *
> 30 * * *
> SiouxCenter-Arista-North(s1)
>
> The reason I stumbled across this is because we've had more than a dozen
> customers over the last month complain about access to Incapsula-protected
> sites. Packet captures show TCP RSTs coming from the far side.
>
> Regards,
>
> Frank Bulk
> AS53347
>
>
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