RE: UC servers not replying every 6th packet

From: Matt Toltzien (Matt.Toltzien@cdw.com)
Date: Thu Apr 10 2008 - 23:40:00 ART


Brad,

I've seen this before... This is by design. Starting in CM 5 there is a
rate limiting feature for ICMP requests.

-Matt

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brad Ellis
Sent: Thursday, April 10, 2008 3:57 PM
To: ccielab@groupstudy.com
Subject: UC servers not replying every 6th packet

Got a strange one here. BOTH of my UC 6.0 servers are not replying to
every 6th ping. Other servers on the same subnet, no issue. Ping is
being initiated from the directly connected switch. I'm learning towards
a DoS type of action from the UC platform, but I wanted to see if anyone
else has seen the same thing.

UC Pub

SWITCH#ping

Protocol [ip]:

Target IP address: 10.2.100.11

Repeat count [5]: 20

Datagram size [100]:

Timeout in seconds [2]:

Extended commands [n]:

Sweep range of sizes [n]:

Type escape sequence to abort.

Sending 20, 100-byte ICMP Echos to 10.2.100.11, timeout is 2 seconds:

!!!!!.!!!!!.!!!!!.!!

Success rate is 85 percent (17/20), round-trip min/avg/max = 1/1/8 ms

UC Sub

SWITCH #ping

Protocol [ip]:

Target IP address: 10.2.100.12

Repeat count [5]: 20

Datagram size [100]:

Timeout in seconds [2]:

Extended commands [n]:

Sweep range of sizes [n]:

Type escape sequence to abort.

Sending 20, 100-byte ICMP Echos to 10.2.100.12, timeout is 2 seconds:

!!!!!.!!!!!.!!!!!.!!

Success rate is 85 percent (17/20), round-trip min/avg/max = 1/2/9 ms

But if you ping anything else on the subnet, it's fine:

SWITCH#ping

Protocol [ip]:

Target IP address: 10.2.100.20

Repeat count [5]: 20

Datagram size [100]:

Timeout in seconds [2]:

Extended commands [n]:

Sweep range of sizes [n]:

Type escape sequence to abort.

Sending 20, 100-byte ICMP Echos to 10.2.100.20, timeout is 2 seconds:

!!!!!!!!!!!!!!!!!!!!

Success rate is 100 percent (20/20), round-trip min/avg/max = 1/1/8 ms

Also, if you ping from a PC, no problems. If you ping FROM the UC box,
no problems.

Anyone else seen this?

thanks,

Brad Ellis

CCIE#5796 (R&S / Security)

CCSI# 30482

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