Zyxel IP Dslam prob

Hi guys!

we hav a scenario in which we have Zyxel IES-1248-71 IP dslam and aztech adsl modem.Now aztech modem sync with dslam but the prob is tht dslam and aztech cant ping each other .
Ips on aztech and dslam are of same subnet

dslam ip = 192.168.1.1/24
aztech modem ip= 192.168.1.2/24
Looback test is successful .There r no filters on the dslam which prohibits ping request packets.Since we r only testing it so i made dslam port and aztech in bridge mode (as we dunt hav any authentication server BRAS at the moment).
I suspect dslam issue rather than aztech's cz i tested 2 aztech modems with same result.Is there any issue with the compatability of aztech modems with zyxel dslam?

Wht can be the problem ?help will b appreciated.

Thnx

Taqqi

Hi Taqqi,

I suspect you network looks like this:

PC --> AZTECH CPE --> Zyxel DSLAM --> Server

And from your post you are logging into the CPE and attempting to ping the DSLAM.

Also you state that the connection within the Zxyel is a bridged connection. Also the connection across the CPE is bridged.

This explains why you cannot ping either the CPE or the DSLAM. Bridged mode means that both the CPE and the DSLAM are acting as Layer 2 (ATM / Ethernet) devices. As such they are not aware of IP layer traffic and so have no way to respond to the PING.

In this setup you will only be able to ping the Server as this is the only other layer 3 (IP) aware device in the setup.

In these situations it is always useful to draw a layerd diagram of the network:

[code:1]

PC CPE DSLAM SERVER
IP

---

IP Layer 3
ETH

---

ETH<->ATM

---

ATM<->ETH

---

ETH Layer 2
\_______CAT 5_________/ \_______DSL_______/ \____FIBRE/CAT 5_____/ Layer 1
[/code:1]

I suspect the IP address given work fine for management, and are unrelated to traffic.

what IP address is on the PC and the Server? They need to be on the same subnet.

br

R

thnx ranger tht explains y they r not pinging each other.
PC's ip add= 192.168.1.2
BRAS Server's ip = 172.16.0.1

But y does they hav to b in the same subnet? i want my users (connecting through CPE) to be not on the same network as my BRAS subnet.so tht broadcasting shuldnt b propagate into my server .i didnt understand tht.cant i keep my cpe in diff subnet then my BRAS ?

Rgds
Taqqi

Hi Taqqi,

Try the following:

Traffic IP Address
===========
PC IP - 192.168.1.2
BRAS - 192.168.1.254

Management IP Address
===============
CPE 192.168.1.1 (so can be manged from the PC)
DSLAM 172,16,0,2
BRAS 172.16.0.1

Then configure a vlan between the DSLAM and BRAS for traffic (i.e. vlan 100), and a second vlan for management (or use default vlan)

Then at the BRAS you have 2 vlans configured downstream 1 for customer traffic and 1 for management traffic.

As for broadcast - I would expect to be able to configure the DSLAM to manage broadcast traffic. It should be able to tell the DSLAM to turn broadcast off so it doen't propogate upstream, but it should allow the dslam to manage downstream broadcasts to the customer connections.

Remember that all traffic has to pass through the BRAS, so when using the described connections (bridged CPE, bridged DSLAM) then the customer PCs have to be on the same subnet as their BRAS interface.

The CPE is basically acting as a media converter, recieveing Ethernet frames from the PC and placing these into ATM (using AAL4 or 5) then transmitting them over DSL on copper. So it's interaction with traffic is minimal.

The DSLAM is acting as an aggregator - taking several customer connectiosn and switching them on to a single VLAN.

Hope this helps

R