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Core Switch (5406zl) virus throttling -- network troubleshooting

Glenn Joseph Andal
Frequent Advisor

Core Switch (5406zl) virus throttling -- network troubleshooting

Hi,

I'm troubleshooting some connectivity issues of our company to other location. Can you interpret the logs I collected in one of our core switch. Attach is the full log and slice log.

Port C4 is the connection of BU1 to the Main BU1 network.

The Main BU1 core switch Virus throttling technology is enable. I checked the logged for port C4 and found some entry.

Now here are some of my queries:

1. Is the High connection rate means that this is a possible attack/virus-like traffic?
2. If it is malicious traffic, if the port is configure to notify-only then the port will be affected from that malicious traffic?
3. for verification: if I throttled the port C4, are the normal traffic flow will not be affected by the mechanism?
4. Is the throttled IP from port C1 may affect connectivity issue from port C4?
5. base on the logs what recommendation can you give us to help us in troubleshooting the intermittent connection of BU1.
2 REPLIES
cenk sasmaztin
Honored Contributor

Re: Core Switch (5406zl) virus throttling -- network troubleshooting

1. Is the High connection rate means that this is a possible attack/virus-like traffic?

yes your log high connection rate possible attack

2. If it is malicious traffic, if the port is configure to notify-only then the port will be affected from that malicious traffic?

have three filtering options
(notify only )report with log or snmp trap.
don't stop malicious traffic

Filtering Options
In the default configuration, connection-rate filtering is disabled. When
enabled on a port, connection-rate filtering monitors inbound IP traffic for a
high rate of connection requests from any given host on the port. If a host
appears to exhibit the worm-like behavior of attempting to establish a large
number of outbound IP connections in a short period of time, the switch
responds in one of the following ways, depending on how connection-rate
filtering is configured:
â   Notify only (of potential attack): While the apparent attack
continues, the switch generates an Event Log notice identifying the
offending hostâ s source IP address and (if a trap receiver is configured
on the switch) a similar SNMP trap notice).
â   Throttle: In this case, the switch temporarily blocks inbound IP
traffic from the offending host source IP address for a â penaltyâ
period and generates an Event Log notice of this action and (if a trap
receiver is configured on the switch) a similar SNMP trap notice.
When the â penaltyâ period expires the switch re-evaluates the traffic
from the host and continues to block this traffic if the apparent attack
continues. (During the re-evaluation period, IP traffic from the host
is allowed.)
â   Block: This option blocks all IP traffic from the host. When a block
occurs, the switch generates an Event Log notice and (if a trap
receiver is configured on the switch) a similar SNMP trap notice. Note
that a network administrator must explicitly re-enable a host that has
been previously blocked.

my advice you can use block filtering option on switch
now occur some attack/virus malicious traffic on network your switch only reporting to you not blocking action
you must be enable block filter option

cenk

cenk sasmaztin
Honored Contributor

Re: Core Switch (5406zl) virus throttling -- network troubleshooting

Global and Per-Port Configuration
connection-rate-filter sensitivity < low | medium | high | aggressive > 3-11
filter connection-rate < port-list > < notify-only | throttle | block > 3-12
show connection-rate-filter < blocked-host >
cenk