Speed mismatch

[NewAdm]

What would the effect be of a speed mismatch be between two routers on the Fa0 interface?

They're connected point to point on the serial interface, Fa0 on each one goes to the LAN on each side.

My initial thought is that they are unrelated, but we've been experiencing issues between these two sites.

 

[burtsbees]

What sort of issues? What kind of line? What kind of routers? Can you post configs and sh int of the serial interfaces?

Burt

 

[NewAdm]

Cisco 1720/21 routers. One of our web apps drops connections on a very irregular basis. T1 point to point connection. We'll call them Trouble and Notrouble

*****Trouble
sh int:

FastEthernet0 is up, line protocol is up
Hardware is PQUICC_FEC, address is 0004.c13f.501b (bia 0004.c13f.501b)
Internet address is 192.168.2.1/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 10Mb/s, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total ou
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 6000 bits/sec, 3 packets/sec
5 minute output rate 8000 bits/sec, 2 packets/sec
617338 packets input, 124842888 bytes
Received 8719 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog
0 input packets with dribble condition detected
710898 packets output, 556502513 bytes, 0 underruns
286 output errors, 1014 collisions, 100 interface resets
0 babbles, 95 late collision, 832 deferred
191 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
FastEthernet0.1 is up, line protocol is up
Hardware is PQUICC_FEC, address is 0004.c13f.501b (bia 0004.c13f.501b)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA
ARP type: ARPA, ARP Timeout 04:00:00
Last clearing of "show interface" counters never
Serial0 is up, line protocol is up
Hardware is PQUICC with Fractional T1 CSU/DSU
Interface is unnumbered. Using address of FastEthernet0 (192.168.2.1)
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 4000 bits/sec, 4 packets/sec
5 minute output rate 5000 bits/sec, 5 packets/sec
723319 packets input, 549984371 bytes, 0 no buffer
Received 8223 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
636734 packets output, 124856221 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 output buffer failures, 0 output buffers swapped out
1 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up

*****Notrouble
sh int:
FastEthernet0 is up, line protocol is up
Hardware is PQUICC_FEC, address is 0002.1762.2
Internet address is 192.168.1.254/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 10Mb/s, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 15000 bits/sec, 8 packets/sec
5 minute output rate 6000 bits/sec, 4 packets/sec
17911852 packets input, 2794523450 bytes
Received 4783541 broadcasts, 0 runts, 0 giants, 0 throttles
72423 input errors, 36327 CRC, 114 frame, 0 overrun, 0 ignored
0 watchdog
0 input packets with dribble condition detected
13424902 packets output, 4269191726 bytes, 0 underruns
5 output errors, 0 collisions, 3 interface resets
0 babbles, 0 late collision, 0 deferred
5 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
Loopback0 is up, line protocol is up
Hardware is Loopback
MTU 1514 bytes, BW 8000000 Kbit, DLY 5000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation LOOPBACK, loopback not set
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
Serial0 is up, line protocol is up
Hardware is PQUICC with Fractional T1 CSU/DSU
Interface is unnumbered. Using address of FastEthernet0 (192.168.1.254)
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 10
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 6000 bits/sec, 3 packets/sec
5 minute output rate 6000 bits/sec, 2 packets/sec
12849865 packets input, 4005067365 bytes, 0 no buffer
Received 188218 broadcasts, 0 runts, 0 giants, 0 throttles
20 input errors, 1 CRC, 12 frame, 0 overrun, 0 ignored, 7 abort
13026754 packets output, 2273185654 bytes, 0 underruns
0 output errors, 0 collisions, 17 interface resets
0 output buffer failures, 0 output buffers swapped out
7 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up


I see a lot of collisions there. I also do not know why a sub-int was set up on fa0

*****Trouble config
Current configuration : 2192 bytes
!
! Last configuration change at 20:46:19 UTC Wed Nov 14 2007 by admin
!
version 12.3
no service pad
service timestamps debug datetime msec
service timestamps log d
service password-encryption
no service dhcp
!
hostname x
!
boot-start-marker
boot-end-marker
!
logging buffered 51200 warnings
enable secret 5 x
!
memory-size iomem 25
no aaa new-model
ip subnet-zero
!
!
no ip domain lookup
ip name-server x
ip name-server x
!
ip flow-cache timeout active 1
ip cef
!
username admin privilege 15 password 7 x
!
!
!
!
interface FastEthernet0
ip address 192.168.2.1 255.255.255.0
ip route-cache flow
speed 10
half-duplex
!
interface FastEthernet0.1
!
interface Serial0
ip unnumbered FastEthernet0
ip route-cache flow
no fair-queue
!
ip classless
ip route 0.0.0.0 0.0.0.0 Serial0
ip route 192.168.1.0 255.255.255.0 Serial0
ip http server
ip http authentication local
ip flow-export source FastEthernet0
ip flow-export version 5
ip flow-export destination 192.168.1.189 9996
!
snmp-server community public RO
snmp-server community private RW
snmp-server location x
snmp-server contact x
snmp-server enable traps snmp authentication linkdown linkup coldstart warmstart

snmp-server enable traps tty
snmp-server enable traps aaa_server
snmp-server enable traps isdn call-information
snmp-server enable traps isdn layer2
snmp-server enable traps isdn chan-not-avail
snmp-server enable traps isdn ietf
snmp-server enable traps hsrp
snmp-server enable traps config
snmp-server enable traps entity
snmp-server enable traps config-copy
snmp-server enable traps frame-relay
snmp-server enable traps frame-relay sub
snmp-server enable traps syslog
snmp-server enable traps cnpd
snmp-server enable traps rtr
banner motd ^C
x Branch Router - Unauthorized Access Is Strictly Prohibited!
^C
!
line con 0
exec-timeout 3 0
password 7 x
login
line aux 0
exec-timeout 3 0
password 7 x
login
line vty 0 4
exec-timeout 3 0
privilege level 15
password 7 x
login local
transport input telnet
!
sntp server x
end

*****Notrouble
Current configuration : 2187 bytes
!
! Last configuration change at 19:21:07 UTC Wed Nov 7 2007 by admin
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname x
!
boot-start-marker
boot-end-marker
!
logging buffered 51200 warnings
enable secret 5 $1$AN89$rjN4u9AIi.1Pd8r7EtJQ61
!
memory-size iomem 25
no aaa new-model
ip subnet-zero
!
!
no ip domain lookup
ip name-server x
ip name-server x
!
ip flow-cache timeout active 1
ip cef
!
username admin privilege 15 password 7 x
!
!
!
!
interface Loopback0
no ip address
!
interface FastEthernet0
ip address 192.168.1.254 255.255.255.0
ip route-cache flow
speed 10
half-duplex
!
interface Serial0
ip unnumbered FastEthernet0
ip route-cache flow
no fair-queue
!
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.1.1
ip route 192.168.2.0 255.255.255.0 Serial0
ip http server
ip http authentication local
ip flow-export source FastEthernet0
ip flow-export version 5
ip flow-export destination 192.168.1.189 9996
!
snmp-server community public RO
snmp-server community private RW
snmp-server location x
snmp-server contact x
snmp-server enable traps snmp authentication linkdown linkup coldstart warmstart

snmp-server enable traps tty
snmp-server enable traps aaa_server
snmp-server enable traps isdn call-information
snmp-server enable traps isdn layer2
snmp-server enable traps isdn chan-not-avail
snmp-server enable traps isdn ietf
snmp-server enable traps hsrp
snmp-server enable traps config
snmp-server enable traps entity
snmp-server enable traps config-copy
snmp-server enable traps frame-relay
snmp-server enable traps frame-relay subif
snmp-server enable traps syslog
snmp-server enable traps cnpd
snmp-server enable traps rtr
snmp-server host 192.168.1.189 version 2c noauth
snmp-server host 192.168.1.189 public
banner motd ^C
WALTON Branch Router - Unauthorized Access Is Strictly Prohibited!
^C
!
line con 0
exec-timeout 3 0
login
line aux 0
exec-timeout 3 0
login
line vty 0 4
exec-timeout 3 0
privilege level 15
password 7 x
login local
transport input telnet
!
sntp server x
end

Any thoughts? I changed speed on Fa0 of trouble to 10

 

[burtsbees]

router(config)#int fa0
router(config-if)#speed auto
router(config-if)#duplex auto

Try that. If the NICs of the nodes on the other ends are set to auto negotiate, you'll get tons of collisions with the current set-up.

Burt

 

[plshlpme]

are your fa0/0 ports connected to fastethernet ports on a switch?

to answer your original question though..

FA0/0 on router1
and
FA0/0 on rotuer2

would have no effect on each other at all..
they are not connected to each other and you could not put enough bandwidth over the T1 line to have any adverse affect on the other

ie one was 100 full and one was 10 half.

T1 is only 1.5mb anyways....


So again.. what are the FA0/0 interfaces plugged into?
obviously full duplex would be better then half to eliminate collisions if you could do it.

Your no trouble router does show some errors on the serial interface.. how old are those counters?


what kind of traffic load is the T1 under while this web app is showing the degradation?

if it is a high load you may need to implement some QOS to make sure it gets the bandwidth reserved to meet the demand...

 

[NewAdm]

They're connect to fast ethernet on both ends. Notrouble was configured for 10/half long before my time for a compatibility issue with a switch. I will be experimenting with it this weekend when no one else is on. The ports are configured for 10/half.

Bandwidth does not seem to be an issue, the load has only peaked to about 500kb

Counters were lifetime counters, I'm the first one to touch these routers since they were implemented many years ago.

A question on some of the commands:
on Trouble -
no service pad - What does this do? Should it be the same on both sides?

ip route -> Serial0 on Trouble VS ip route -> 192.168.1.1 Notrouble - Do these essentially mean the same thing?

on Notrouble -
no fair-queue - What does this do? Should it be the same on both sides?

Thanks for all of the help!

 

[NewAdm]

Nevermind the fair-queue thing, I don't know how to read =P

 

[jneiberger]

You have a duplex mismatch on Trouble and the device it is connected to. You have it set for half duplex but the other side is operating at full duplex. You can tell this is happening because of the late collisions. Set both sides to auto and see if it clears up. If that doesn't work then the device is not negotiating properly so you'll need to manually configure your router to operate at full duplex.

 

[jneiberger]

I forgot to say two other things. First, how long have these links been up? I'd like to know how old those counters are. Second, collisions are completely normal and expected on half duplex links. They do not indicate a problem.

Late collisions, on the other hand, do indicate a problem, usually a duplex mismatch but it can also be a bad cable.

 

[NewAdm]

The links have been up for years, but we have just recently started using a web app that is generating more traffic. We have outside users that are able to connect, it's just users on the other side of Trouble that are having issues. Their connections are dropping in the middle of sessions (it's an oracle app). It sporadically affects some users, sometimes all users go down at once.

The counters were from the first time the router was set up before my time here. I have reset the counters and I'm still getting collisions on Trouble (no late collisions), but 58 in 45 minutes vs none on Notrouble.

I manually configured the port on Trouble side to 10/h. I am going to be investigating changing over to auto/auto on both sides.

It's so inconsistent is the maddening part.

 

[jneiberger]

If you see any late collisions after clearing the counters then you almost surely have a duplex mismatch. That will give you horrible performance and you should fix it immediately if you see it.

Regular collisions on a half duplex link are totally normal and nothing to worry about. A collision is not an error and not an indication that any at all is out of the ordinary.