set one end to 100 half and the other to 100 full and see what happens....:)
Priscilla Oppenheimer wrote: >Larry Letterman wrote: > >>Most likely the previous 10/half interface on the switch and >>the router >>were not >>linked at the same speed/duplex or the other router had an >>issue with >>the setting. >> > >No, the switch and router were set to the same thing, which was 10 Mbps half >duplex, if you read his messages. He was using a 2500 router. Those routers >predate the full duplex standard. In fact they may predate 100 Mbps also. He >had no choice but to upgrade the router, which he did. > >He was seeing lots of collisions, including excessive collisions where the >frame got dropped because even after 15 retries it encountered a collision. > >Collisions are normal in shared (half-duplex) Ehternet, but excessive >collisions are not. Collisions are caused by the stations on the shared link >simultaneously sending. Excessive collisions are due to a shortage of >capacity. One fix to the problem is to increase the capacity. By jumping >10-fold from 10 Mbps to 100 Mbps, the risk of collisions, especially >excessive collisions, goes way down. Since each frame takes 1/10th the >amount of time to send, the odds that some other station is sending when >another station transmits (or retransmits) go way down. > >Increasing capacity used to be the only way we could upgrade an Ethernet >network. Then the full-duplex standard came about. It can only be used on a >point-to-point link where each side has its own dedicated transmit path. In >other words, it's no longer shared Ethernet. There's no need to sense >carrier to see if anyone else is sending, because there isn't anyone else. >It's not multiple access. Receiving while you're sening is legitimate, so >there's no need to check for collisions. It's no longer CSMA/CD. Of course >the collision rate goes down. Collisions really have no meaning in this >environment. If there are collisions, then there's probably a duplex mismatch. > >So, anyway, he improved matters in two ways: upgrading the capacity and >moving to full duplex. > >I just wanted to add this theory discussion. It's not right to say (as >someone else did) that collisions are "caused by" a half-duplex setting. >Collisions are caused by two stations sending at once, which tends to happen >more and more frequently when there's not enough capacity to support the >sending behavior of the nodes on the shared network. To fix the problem, you >can increase capacity or you can make the network not shared by connecting >just two devices and using full duplex. > >_______________________________ > >Priscilla Oppenheimer >www.troubleshootingnetworks.com >www.priscilla.com > >>To be safe I would set the switch port and the router interface >>to >>100/full or 10/full >>and there should be no issues then. >> >>and yes, the fast ethernet in the 26XX/36XX routers are a >>better >>solution..... >> >>Larry Letterman >>Cisco IT-LAN , San Jose >> >>Cliff Cliff wrote: >> >>>Today, We are put 3660 router to their end, having >>> >>Fastethernet card, and >> >>>connected to their switch. >>> >>>They change their switch port as following: >>> >>>interface FastEthernet0/14 >>>load-interval 30 >>>duplex full >>> >>>so far, after observe serveral hours, there is no collision as >>> >>well as not >> >>>error message in our router. >>> >>>So, what's wrong? Is the fastethernet is better? or previous >>> >>setting that I >> >>>have is wrong? Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=58485&t=58389 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
