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Author Topic: mac-address-table only holds 512 entries?  (Read 13470 times)

gmans111

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mac-address-table only holds 512 entries?
« on: October 30, 2009, 09:54:37 AM »

I noticed DGS-1224T was sending traffic some to all ports (like a hub), rather than switching.  The destination(s) are missing from the mac-address-table.

When I count total number of entries in dynamic mac-address-table, it constantly hovers around 500.  It NEVER goes over 512.  Is this the max it can handle?  512 entries?

Under 'Specifications', it claims Mac Address Table Size is 8K.  (http://www.dlink.com/products/?pid=DGS-1224T)
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Fatman

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Re: mac-address-table only holds 512 entries?
« Reply #1 on: October 30, 2009, 10:55:15 AM »

umm this doesn't sound right.  I am going to look into this for you.
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lizzi555

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Re: mac-address-table only holds 512 entries?
« Reply #2 on: November 03, 2009, 11:00:36 AM »

8K = 8192 Byte
1 MAC = 16 Byte
8192 / 16 = 512 entries

Looks ok  ;)
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Fatman

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Re: mac-address-table only holds 512 entries?
« Reply #3 on: November 03, 2009, 02:32:44 PM »

OK, I have managed a little bit of testing so far, and I am still waiting on an officious answer.  What HW and FW rev are you using?

I realize you were being light hearted, but I feel compelled to add that MAC Addresses are 48 bits (6 Bytes) long, that's not to say that a line in an ARP table wouldn't be 16 Bytes long, though I don't know for certain how long they would be for this product.
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gmans111

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Re: mac-address-table only holds 512 entries?
« Reply #4 on: November 05, 2009, 03:03:48 PM »

I have a whole bunch of these switches (about half are still sitting in my cube), but the particular one that prompted my post is hardware version D2, firmware 4.21.01.

Thanks for looking into this.
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gmans111

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Re: mac-address-table only holds 512 entries?
« Reply #5 on: November 20, 2009, 02:17:54 PM »

Hate to be a pest, but... any more news?

I'm more than willing to test-drive debug/development firmware, if that helps.

I need to get past 512 entries.  I temporarily replaced this switch with another brand/model to verify that I've got ~890 mac addresses out there.

Thank you.
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Fatman

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Re: mac-address-table only holds 512 entries?
« Reply #6 on: November 23, 2009, 08:38:12 AM »

I have not been able to recreate your results.  I was using a full 1500 addresses in my tests without failure.

My apologies for the delay, I thought I had already posted as much in this thread.
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Fatman

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Re: mac-address-table only holds 512 entries?
« Reply #7 on: November 23, 2009, 08:39:51 AM »

Also, I think it would be interesting to get you to call in so they can make sure we don't have any obvious problems, then they can get your hardware swapped (and if the tech is any good he will have your switch shipped to HQ for testing).
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gmans111

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Re: mac-address-table only holds 512 entries?
« Reply #8 on: November 30, 2009, 11:35:24 AM »

All of my DGS-1224T's are currently out-of-service, pending our findings with this issue.  Soon as I can muster, I'll slip a different unit into the network to see if it behaves any differently.  Stay tuned.

Meanwhile... I had another thought.

I was using snmp to count the number of entries in mac-address-table.  Can you please test that too (using your 1500 address setup)?

$ snmpwalk -v2c -c public <hostname> .1.3.6.1.2.1.17.4.3.1.2 | wc -l

Maybe I'm jumping to a conclusion by combining two different symptoms?
   1.  Unexplained traffic sent to all ports
   2.  SNMP dot1dTpFdbPort only displays upto 512 entries
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