For us here, with 28,000+ Ethernet ports. By default all our ports are set to auto. If the device on the other end can't support autonegotiation, only than do we hard-set ports.
Keep in mind on a lot of gear (Cisco included) that at 10/100 speeds, half-duplex is the default for duplex negotiation failure. This means if you hard-set one end to 100/Full and the other is auto, 99% of the time the auto side will come up 100/Half. Rule of thumb for us is, both sides are auto, or both sides are hard-set. 1gb speeds 'Full' is the default, but we still leave those ports at auto, and let the FLP's handle the negotiation. Ken Matlock Network Analyst Exempla Healthcare (303) 467-4671 [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jeff Wojciechowski Sent: Thursday, May 20, 2010 1:19 PM To: [email protected] Subject: [c-nsp] Ethernet Interfaces Speed and Duplex - Force or Auto All: Curious what other network admins are doing out there for Ethernet interfaces as far as speed and duplex settings - weather to specify or to leave them auto negotiate. The reason I am asking is we just installed some equipment in a new data center we are in the process of bringing online for redundancy and the switch ports on the network switch at the new location are set to 100/full while the switch this equipment was built and tested on in our main facility was set to auto/auto. Since equipment was moved to the new location I have been taking CRC errors on almost all active network ports that this equipment is plugged into yet the 3 months or so this system was in the other location with speed auto/duplex auto, we had none. I tried swapping out the network switch but I am still taking errors at about the same rate. Show int of port with most errors (WS-C3560-24TS) FastEthernet0/3 is up, line protocol is up (connected) Hardware is Fast Ethernet, address is 001c.0f21.d085 (bia 001c.0f21.d085) MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full-duplex, 100Mb/s, media type is 10/100BaseTX input flow-control is off, output flow-control is unsupported ARP type: ARPA, ARP Timeout 04:00:00 Last input never, output 00:00:01, output hang never Last clearing of "show interface" counters 1d18h Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/0 (size/max) 5 minute input rate 2000 bits/sec, 3 packets/sec 5 minute output rate 3000 bits/sec, 4 packets/sec 533310 packets input, 64455460 bytes, 0 no buffer Received 5227 broadcasts (0 multicasts) 0 runts, 0 giants, 0 throttles 150 input errors, 69 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 0 multicast, 0 pause input 0 input packets with dribble condition detected 556098 packets output, 59830579 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier, 0 PAUSE output 0 output buffer failures, 0 output buffers swapped out During non-production hours, I will be setting those ports to auto/auto to see if the errors go away - but still curious what others are doing - and does it depend on what sort of device is using a port such as a server, router, another switch, pc, etc? Thanks again, Jeff Wojciechowski LAN, WAN and Telephony Administrator Midland Paper Company 101 E Palatine Rd Wheeling, IL 60090 * tel: 847.777.2829 Ê fax: 847.403.6829 e-mail: [email protected]<mailto:[email protected]> http://www.midlandpaper.com _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
