[c-nsp] Weird ADSL bridging issue

[Scott Granados]

I’m wondering if you need a no proxy arp on your interface.  I don’t see it in the included config.

On Dec 12, 2014, at 11:03 AM, chris <tknchris at gmail.com> wrote:

> 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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