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ASA5520 stops forwarding, or what ?

I have an customer with an ASA5520, 100Mbit internet and 4000 pc's.

A couple of times each day, tha ASA stops forwarding packets. Its still alive, and i can access it from outside. From inside it looks dead.

Sometimes just removing end reinserting the cable in the inside interface can start it again. Other times only an reboot helps.

Thi inside is connected to an HP5300 switch, both ports fixed at 100Mbit fd.

HELP !! i am running out of ideas.

Nothing special in the syslog, nothing special from the ssm module. Last message on the ASDM log is "connection to syslog server lost.

Syslogging are udp.

Per Buch


Community Member

Re: ASA5520 stops forwarding, or what ?


Maybe you should try sniffing the internal network to check for traffic, like to host or protocol.

I have a case where the internal server keeps sending ARP flood. It slow down the network.

Community Member

Re: ASA5520 stops forwarding, or what ?


We are sniffing the internal network, can't find anything special there. The network is not slowing down, its the internetconnection thats going down.

The traffic goes from 40-50 mbit/s to 0.

Connections goes from around 100/s to 0.

The IPS repports a lot of "tcp syn" but most of them looks like false positives.

There are times where the number of udp connections suddenly rises to around 200/s, but i cant se what is causing it.

Could it be default gateway spoofing ?

Would that explain this behavior ?

Per Buch

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