Hi guys, I am replying in-line ...
-----Original Message----- From: Michael van Elst [mailto:mlelstv@serpens.de] Sent: Thursday, March 06, 2003 8:48 PM To: Hill, Aaron Cc: 'toasters@mathworks.com'
On Thu, Mar 06, 2003 at 06:31:18PM -0600, Hill, Aaron wrote:
Hey, thanks for the info.
Here is the network path;
Source Filer GigE ----- GigE on 4006 Cisco switch 100/FastE ---- 100/FastE 3660 Router 100/FastE ==== 20M VLAN ==== 100/FastE 3600 Router 100/FastE ---- 100/FastE 2924 Cisco Switch 100/FastE ---- 100/FastE
Target Filer
I see a pair of 3660's in the middle. Are they one of the first ones you had? They are fast and they are 'divisional' class routers. They can operate HSSI interfaces up to DS3 speeds effectively, but take a look at the processing of them. What is the cpu utilization. You are most likely using the FA0/0 and FA 0/1, but just asking. Are you doing any routing protocols, ect? I am digging so please bear with me. I am pointing out potential issues. Also make sure you have the full version IOS on these routers. When I got my first pair, I was doing DS3's to a web site, and I got a pre-release of the cisco IOS on there. Just something to check. We did upgrade, because of a bug. ( harware related ) Look at the couters on the int's for ANY errors. If you packets are seeing any issues, then you will see it there. Also, at 20 megabit, you will see about 1.6 megabytes MAX theoretical. Are you ever seeing that anywhere? FTP, makefiles ect.? Try to establish the baseline. I saw you say you got it from ftp, but that speed? Just curious.
The VLAN carrier, UECOMM tells us no traffic shaping on the
VLAN given
to us.
I have seen AT&T do this here in the US. You can get good speeds, but it is burst.
Our network team has no traffic shaping on the 3660 nor the 3600.
See anything else in there causing an issue?
Not off hand. Anything else happening on the WAN when you are doing this? Are you getting dedicate CIR rates from the carrier. Do you have any TSU's or DSU like terminaing devices. Check framing. I think that it is possible that the filer can POUND that link into a submissive state. That is not to say we shouldn't get max speeds, but snapmirror CAN be unrelenting. You need to try and harden the link, and packet shaping can help. The original request to turn on flow control is good if you have the option. This will aid the source and destination in any fragmentation or retrans type issues.
Are you seeing any errors in the ifstat information. CRC, checksum errors, anything?
I would start looking at flow-control settings for the GigE on the 4006 and also verify the MTU sizes on each interface to rule out packet fragmentation.
Sounds good.
But I still suspect the 20Mbps bandwidth limit to have a significant effect. To make this more visible you could enable traffic shaping on your routers with a slightly smaller limit.
This will keep you from crippling the link. Snapmirror was designed with campus speeds in mind. The throttle came when wan and DR was introduced. If you can throttle to 1.7 megabit, the you will see a possible performance increase. Sort of like stopping a potential 'downward spiral'.
-- Michael van Elst Internet: mlelstv@serpens.de "A potential Snark may lurk in every tree."
Rich B