 | Start a set with this search |
 | Include this search in one of my sets |
 | Exclude this search from one of my sets |
 | Permalink to these results Paste this link in email or IM: |
 | Atom feed for tracking future search results Paste this URL into your reader: |
12 messages in net.nether.puck.cisco-nsp[c-nsp] MTU Question on T1| From | Sent On | Attachments |
|---|---|---|
| Richard J. Sears | Jan 24, 2005 12:33 pm | |
| Gert Doering | Jan 24, 2005 12:54 pm | |
| Richard J. Sears | Jan 24, 2005 1:13 pm | |
| Gert Doering | Jan 24, 2005 1:28 pm | |
| Joe Maimon | Jan 24, 2005 1:28 pm | |
| Jon Lewis | Jan 24, 2005 1:39 pm | |
| Rodney Dunn | Jan 24, 2005 2:39 pm | |
| Bill Wichers | Jan 24, 2005 7:46 pm | |
| Richard J. Sears | Jan 24, 2005 8:15 pm | |
| Jon Lewis | Jan 24, 2005 8:18 pm | |
| Jay Hennigan | Jan 24, 2005 8:27 pm | |
| Gert Doering | Jan 25, 2005 3:08 am |
| Permalink for this message Paste this link in email or IM: |
| Permalink for this thread Paste this link in email or IM: |
| Atom feed for this thread Paste this URL into your reader: |
| Subject: | [c-nsp] MTU Question on T1 | Actions... |
|---|---|---|
| From: | Richard J. Sears (rse...@americanIS.net) | |
| Date: | Jan 24, 2005 12:33:25 pm | |
| List: | net.nether.puck.cisco-nsp | |
I have a interesting situation that I would like to run by everyone and see if anyone has run into this before.
I have a vendor with two pieces of equipment. Here is the layout:
Vender Equipment -> FE on Router -> Dual Multilink T1s -> Router -> FE on Vender Equipment
Right now the equipment is not working as advertised. According to the vendor, this is because a ping of 40000 bytes is returning a rtt of 400ms across the dual T1s.
Sh ints on all interfaces show no errors, no crcs, no drops, etc.
In our tests, there is nothing running on the link other than the vendor equipment. They also suggested setting up LLQ (which we did) on the routers and there was no change in the performance of their equipment.
Their entire claim is that because they cannot ping the other router with a 40000 byte packet with less than 50ms latency, that is the entire problem and until we fix that issue - don't call them back.
So - my brain begins to think and I go to my 7500s, ping any number of customers with T1s with no traffic on them with Cisco's max packet size of 18024 - I see around 225ms.
Each T1 is set with an mtu of 1500 bytes, which means that every 40000 byte packet have to be broken up into almost 27 packets, get sent across the T1, be put back together and then reverse that process in order to get the RTT.
I do not see any place to increase the MTU on a Cisco T1 WIC card (if even we would want to), nor do I see errors.
After looking at about 20 different T1s - I get the sense that I won't see anything less than 300 to 400ms doing a 40000 byte ping test across two Cisco 1720's.
I just want to see if I missed something or if my logic is off before going back to the drawing board with these guys.
Any improvements in my logic or suggestions would be great.
Thanks !!
****************************************** Richard J. Sears Vice President American Internet Services
---------------------------------------------------- rsears at adnc.com http://www.adnc.com
---------------------------------------------------- 858.576.4272 - Phone 858.427.2401 - Fax INOC-DBA - 6130
----------------------------------------------------
I fly because it releases my mind from the tyranny of petty things . .
"Work like you don't need the money, love like you've never been hurt and dance like you do when nobody's watching."