• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1483
  • Last Modified:

ALCATEL 7342 blocking Arp Responses

Basically i have an Alcatel 7342 that is blocking the return Arp responses. Does anyone know how to get around this?


CISCO 7604-------->ALCATEL 7342-------->MP124

I have looked at the Arp Table on the CISCO and it stays incomplete for around 8 minutes after the Arp UPdate. I also looked at the ip cef and it gave me the valid glean adgecency thus telling me that there is no response. I moved teh MP directly to the CISCO and tried it again and it worked fine. Can somone tell me if there is something in the AlcaTel 7342 that may be causing this behavior.


Thank you,

TAMSCODAN
0
TAMSCODAN
Asked:
TAMSCODAN
  • 5
  • 2
  • 2
1 Solution
 
woolmilkporcCommented:
Hi,
afaik the Alcatel 7342 is basically a router. Each router will block outgoing arp requests and will answer them by inserting its own MAC Address. This is normal behaviour, since the router must handle outgoing traffic, and the machines behind it must take the path over the router, thus are forced to send outgoing packets to the router's MAC, regardless of which IP might actually be the target.
 
wmp
 
0
 
TAMSCODANAuthor Commented:
Is there any way that we can force the Alcatel not to proxy the response?
0
 
woolmilkporcCommented:
No, as long as it is acting as a router.
I don't know whether one could reconfigure it as sort of a bridge/repeater, but I don't think so.
You might want to consult the manuals of the 7342. I for one don't know enough about this machine to help you with that.
 
wmp
 
0
Get free NFR key for Veeam Availability Suite 9.5

Veeam is happy to provide a free NFR license (1 year, 2 sockets) to all certified IT Pros. The license allows for the non-production use of Veeam Availability Suite v9.5 in your home lab, without any feature limitations. It works for both VMware and Hyper-V environments

 
harbor235Commented:

Is this passive optical networking? the Alcatel device is a OLT? More information is needed, I also assume the mp124 is a voice gateway?

How are you testing the MP124 connected directly works? What are you doing when the ALcatel fails

Please provide more detailed information

harbor235 ;}
0
 
TAMSCODANAuthor Commented:
The Alcatel OLT is not a Passive Device. The MP-124 is the Voice GW. When the MP-124 is Connected Directly to the CISCO and the Arp table creates a request the MP-124 responds Immediately, however when it is connected after the OLT it appears that the responses do not make it through the Alcatel. For some reasons only gratuitous ARP's from the MP-124 makes it to the CISCO however when the time expires on the Arp entry then the CISCO makes an ARP request and there is no reply back.

When the connection fails I look at the arp  entry, and it shows incomplete, then I look at the cef entry and it shows that the ARP was sent but there has been no response received.

The only way for the system to work is to create a static Arp Entry for each MP-124
0
 
TAMSCODANAuthor Commented:
CISCO 7604-------->ALCATEL 7342-------->MP124
0
 
harbor235Commented:
ok, so you are using GPON, the Alcatel 7342 is thier flagship gigabit passive optical network solution.
Passive meaning that you are using optical splitters that split the signal between the OLT and the potential ONTs downstream.  

Do you have a ONT connected like the following?

Alcatel 7342 ------> ONT -----> MP124

The 7342 uses GEM encapsulation and the ONT strips that and bridges the ethernet frames

The 7342 is not a bridge/switch it forwards encapsulated frames, on the downstream it forwards/broadcasts to every ONT/host on the PON, it also encrypts all downstream traffic using AES 128, you need an ONT to decrypt. The upstream traffic is given a time slot and forwarded up to the layer 3 device.

Because of the GPON architecture I would not locate the voice GW on PON, I would create a network directly connected to the 7600, this would give you better performance and better ethernet utilization.

harbor235 ;}
0
 
TAMSCODANAuthor Commented:
my connectivity is:

CISCO 7604---->Alcatel 7342------->ONT------->MP124

on my cisco every 4 hours when the CISCO sends a request for an ARP update to the MP 124 there is no reponse back for at least 8 minutes. Now if I make a static ARP entry in the CISCO communications work fine. For some reason I'm not getting a response back from the CISCO. I am wondering if the MP is even getting a request to it. hummm!! Do you think the ONT is my problem either blocking the request from the CISCO or the response from the MP?

I know that if we power cycle the MP then the gratuitous ARP traverses the network without a problem and the CISCO 7600 updates its table immediately. The other solution was the static arp entry.
0
 
TAMSCODANAuthor Commented:
I will have to get with Alcatel to trace this issue. Thank you.
0

Featured Post

Free learning courses: Active Directory Deep Dive

Get a firm grasp on your IT environment when you learn Active Directory best practices with Veeam! Watch all, or choose any amount, of this three-part webinar series to improve your skills. From the basics to virtualization and backup, we got you covered.

  • 5
  • 2
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now