[c-nsp] Weird ADSL bridging issue

[chris]

Just an update for the archives. Karsten nailed it with the default route
pointing to the bvi. 20 hours later and no more weird mac addrs in arp.
Thanks everyone who replied

chris

On Fri, Dec 12, 2014 at 1:51 PM, Karsten Thomann <karsten_thomann at linfre.de>
wrote:
>
>  no proxy arp on your router has nothing to do with it, the proxy arp is
> done by the redback, you have to make sure that your route is not pointing
> to the bvi without next hop, and that there is a right default route from
> dhcp.
>
>
>
> Is there any configured static route in the configuration like "ip route
> 0.0.0.0 0.0.0.0 bvi1"?
>
>
>
> I don't have the exact command in mind, but there is a command at "show ip
> dhcp" or "show dhcp" where you can see what settings you got from the
> provider dhcp server.
>
>
>
> Am Freitag, 12. Dezember 2014, 13:34:00 schrieb chris:
>
> I added "no ip proxy-arp" under BVI1 and rebooted the router to clear all
> the entries in the arp table and right away as soon as the circuit came up
> and i logged in I'm still seeing the same random MAC's and alot of them
> even though its only up a few minutes.
>
>
> To keep email from getting too long I've posted debug info here:
> http://pastebin.com/AxMB3mw8
>
>
>
>
> On Fri, Dec 12, 2014 at 11:29 AM, Karsten Thomann <
> karsten_thomann at linfre.de> wrote:
>
> Hi Chris
>
> Is there any configured default route on the router?
> Is it possible to post output of sh ip route?
> This looks like a default route without next hop ip and proxy arp at the
> provider...
>
> Kind regards
> Karsten
>
> Gesendet von meinem BlackBerry
>   Originalnachricht
> Von: chris
> Gesendet: Freitag, 12. Dezember 2014 17:21
> An: cisco-nsp at pu ck.nether.net
> Betreff: [c-nsp] Weird ADSL bridging issue
>
> Hello,
>
> We have a small site we inherited that is still on ADSL on legacy sprint in
> the northeast.
> The ILEC is using aal5snap and we have a WIC-1ADSL with a physical ATM
> interface thats bridged to BVI1, and we get a dynamic WAN ip from the ILEC
> via DHCP on BVI1.
>
> the ADSL part of our config looks like this:
>
> *bridge irb*
> *!*
>
> *interface ATM0/0*
> * description DSL Layer2*
> * no ip address*
> * atm restart timer 300*
> * no atm ilmi-keepalive*
> * dsl operating-mode auto *
> * clock rate aal5 7000000*
> * clock rate aal2 7000000*
> * bridge-group 1*
> * bridge-group 1 spanning-disabled*
> * hold-queue 224 in*
> * pvc 8/35 *
> * encapsulation aal5snap*
> * !*
> *!*
>
> *interface BVI1*
> * ip address dhcp*
> * ip nat outside*
>
> I was looking internet into a report of weird internet issues and I found
> the arp table for BVI1 is full (several pages) of lots of random internet
> IP's with the same MAC address which isnt local to the router:
>
> *Protocol Address Age (min) Hardware Addr Type Interface*
> *Internet 17.110.228.155 26 0030.881b.f475 ARPA BVI1*
> *Internet 8.8.8.8 162 0030.881b.f475 ARPA BVI1*
> *Internet 23.3.13.24 25 0030.881b.f475 ARPA BVI1*
> *Internet 17.110.228.154 84 0030.881b.f475 ARPA BVI1*
> *Internet 74.209.254.102 24 0030.881b.f475 ARPA BVI1*
> *Internet 74.125.228.215 29 0030.881b.f475 ARPA BVI1*
> *Internet 173.194.121.18 29 0030.881b.f475 ARPA BVI1*
> *Internet 17.110.228.159 84 0030.881b.f475 ARPA BVI1*
> *Internet 69.172.216.55 24 0030.881b.f475 ARPA BVI1*
> *Internet 4.2.2.2 162 0030.881b.f475 ARPA BVI1*
> *Internet 31.13.69.80 25 0030.881b.f475 ARPA BVI1*
> *Internet 173.194.121.17 26 0030.881b.f475 ARPA BVI1*
> *Internet 17.110.224.152 36 0030.881b.f475 ARPA BVI1*
> *Internet 66.196.81.223 2 0030.881b.f475 ARPA BVI1*
> *Internet 74.125.228.219 21 0030.881b.f475 ARPA BVI1*
> *Internet 17.167.146.44 22 0030.881b.f475 ARPA BVI1*
> *Internet 173.194.121.30 26 0030.881b.f475 ARPA BVI1*
> *Internet 17.172.239.90 35 0030.881b.f475 ARPA BVI1*
> *Internet 74.122.189.133 97 0030.881b.f475 ARPA BVI1*
> *Internet 173.252.79.23 49 0030.881b.f475 ARPA BVI1*
> *Internet 17.173.255.74 144 0030.881b.f475 ARPA BVI1*
>
> Interestingly enough when I look up the OUI of that MAC I see Sierra
> Systems aka Redback which I happen to know is the DSLAM that the ILEC is
> using.
>
> Anyone seen anything like this? I am trying to figure out if its an issue
> with the bridging on the local router or telco misconfiguration.
>
> I rarely touch any ATM anymore so I'm scratching my head here but hoping
> something obvious might stand out to someone.
>
> TIA,
> chris
>
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