Surestream issues with load sharing

Unanswered Question
Mar 26th, 2010


Got an issue with a surestream (2*SDSL: 2ATM, 2 DIalers tunning static routes). I am using load sharing as I would like to get the traffic using both line at the same time.

I am using ip cef and the cmd ip load-sharing per-packet on each dialer. In my CEF table I am able to see both virtuall-accesses.

All is working fine ***but**** if one line bounced and comes up, dialer comes up, virtual access come up too, can see the session in my sh users but in the CEF table this virtuall access is not appearing anymore

Need your brain guys



I have this problem too.
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Paolo Bevilacqua Fri, 03/26/2010 - 06:52

You should not use load sharing per packet.

It cause out of order packet arrival, consequently  is very detrimental for most applications.

melaniemaillet Fri, 03/26/2010 - 07:34


Thanks for your answer.

I was thinking it was only for voice over ip, in my case we are not using VOIP, will be still an issue?

As if it's not good to use it, I am not sure waht to use to get the both line used at the same time.


Ronit Bhattacharjee Fri, 03/26/2010 - 13:40

Hi Melanie,

As p.bevilacqua pointed out, it is not recommended to use per-packet load sharing unless we are sure both the links have similar latency and converge on the same device at the next-hop. This is almost impossible for internet links; even if the links are from the same ISP.

You can use per-destination load sharing (default) which would get you better results (though not perfectly equal bandwidth distribution)

Hope this helps

melaniemaillet Mon, 03/29/2010 - 00:52

Thank you all Will put back the load sharing per destination to improve the BW share. But even with that I still have the bug after bouncing one of the line, once the line comes back up, and i can see the virtual access up under my sh users, I still cannot see it from the CEF table. Could it be an IOS issue?

Thanks in advance for your help.

Ronit Bhattacharjee Mon, 03/29/2010 - 04:09

Hi Melanie,

Please send a capture of the cef table during normal operation and during the issue along with a "show ver" from the router.

Also, once one of the links has bounced (and come back UP) and is missing from the CEF table, what do you do to restore normal operation?


melaniemaillet Mon, 03/29/2010 - 06:20


To get it working fine I have to clear the CEF I know that's not good.

In The CEF table below we can see allis working fine, but if Virtual-Access2 bounced and comes up again, it won't appear anymore in teh CEF table.

sh ip cef
Prefix              Next Hop             Interface           X.X.X.C         Virtual-Access2
                    X.X.X.C         Virtual-Access3          receive
X.X.X.C/32          attached             Virtual-Access2
                    attached             Virtual-Access3
Y.Y.Y.Y/32    receive
S.S.S.S/32    receive
........./29  attached             FastEthernet0/0
........./32  receive
.........32  receive
........./32  .........     FastEthernet0/0
........./32  receive
........./4         drop
........./24        receive
........./32  receive

#sh ver
Cisco IOS Software, 1841 Software (C1841-ADVIPSERVICESK9-M), Version 12.4(5b), RELEASE SOFTWARE (fc2)
Copyright (c) 1986-2006 by Cisco Systems, Inc.
Compiled Tue 18-Apr-06 18:41 by ssearch

ROM: System Bootstrap, Version 12.4(13r)T, RELEASE SOFTWARE (fc1)

System returned to ROM by Reload Command
System image file is "flash:c1841-advipservicesk9-mz.124-5b.bin"

Cisco 1841 (revision 7.0) with 97280K/33792K bytes of memory.

2 DSL controllers
2 FastEthernet interfaces
2 ATM interfaces
1 Virtual Private Network (VPN) Module
DRAM configuration is 64 bits wide with parity disabled.
191K bytes of NVRAM.
31488K bytes of ATA CompactFlash (Read/Write)

Configuration register is 0x2102


Ronit Bhattacharjee Mon, 03/29/2010 - 07:16

Hi Melanie,

The symptoms you’re seeing are most probably being caused by bug CSCsh71247. See more details for this bug here (you'll need a cco account)

This bug is fixed in 12.4(13) and above. To confirm whether this is the bug, when the problem occurs again, get a "show adjacency", it should show something like this

Protocol Interface Address

IP Virtual-Access3 point2point(8) (incomplete)

Hope this helps!!!

melaniemaillet Mon, 03/29/2010 - 08:28

Hi Ronit,

Thanks for that

I will test the router with this new IOS version




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