Do you think the interface BW is normal in C3560

eigrpy · ‎11-17-2015

Hi, Do you think the interface BW is normal in C3560. The switch has 24 fast ports and 2 giga ports. The giga port' BW is 10000 Kbit, while fast port BW is 100000 Kbit. What can cause the issue? The below is output of interface, Thank you

Switch Ports Model SW Version SW Image
------ ----- ----- ---------- ----------
* 1 26 WS-C3560-24PS 12.2(25)SEE2 C3560-IPBASEK9-M

-----------------------

Switch#sh int gigabitEthernet 0/2
GigabitEthernet0/2 is down, line protocol is down (notconnect)
Hardware is Gigabit Ethernet, address is 0019.56b4.cd02 (bia 0019.56b4.cd02)
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Auto-duplex, Auto-speed, link type is auto, media type is Not Present
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
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: 0/40 (size/max)
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 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 1 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

Switch#sh interfaces fastEthernet 0/1
FastEthernet0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0019.56b4.cd03 (bia 0019.56b4.cd03)
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 00:01:59, 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 0 bits/sec, 0 packets/sec
5 minute output rate 1000 bits/sec, 1 packets/sec
77 packets input, 6737 bytes, 0 no buffer
Received 77 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 73 multicast, 0 pause input
0 input packets with dribble condition detected
142 packets output, 10954 bytes, 0 underruns
--More--

Peter Paluch · ‎11-17-2015

Hi,

On Ethernet-type interfaces, switches automatically adjust their reported bandwidth depending on the result of autonegotiation, that is, the speed the port has negotiated with its link partner. Obviously, a port that is down/down is treated as a 10Mbps port (the slowest Ethernet available), hence the reported bandwidth. As the FastEthernet port has negotiated 100Mbps operation with its link partner, the reported bandwidth also corresponds to 100Mbps.

The bandwidth indication on a Gigabit Ethernet port (or any Ethernet port for that matter) will make sense only when the port is up/up, and it will correspond to the negotiated speed.

Best regards,
Peter

eigrpy · ‎11-17-2015

Thank you so much for your reply. If I want to know the physical speed of the port, how can I know that? Is the BW could be its speed ? Thank you

Peter Paluch · ‎11-18-2015

Hi,

With Ethernet-type interfaces, the maximum supported speed can be directly inferred from the name of the interface:

Ethernet: 10 Mbps
FastEthernet: 10/100 Mbps
GigabitEthernet: 10/100/1000 Mbps
TenGigabitEthernet: 10/100/1000/10000 Mbps

On switches, you can also use the show interface interface-name capabilities command to find out about the interface capabilities including supported port speeds:

Switch# show interface gi0/1 capabilities
GigabitEthernet0/1
Model:                 WS-C3560G-48TS
Type:                  10/100/1000BaseTX
Speed:                 10,100,1000,auto
Duplex:                half,full,auto
Trunk encap. type:     802.1Q,ISL
Trunk mode:            on,off,desirable,nonegotiate
Channel:               yes
Broadcast suppression: percentage(0-100)
Flowcontrol:           rx-(off,on,desired),tx-(none)
Fast Start:            yes
QoS scheduling:        rx-(not configurable on per port basis),
                         tx-(4q3t) (3t: Two configurable values and one fixed.)
CoS rewrite:           yes
ToS rewrite:           yes
UDLD:                  yes
Inline power:          no
SPAN:                  source/destination
PortSecure:            yes
Dot1x:                 yes

On copper (twisted pair) interfaces, the interface usually supports all speeds from 10 Mbps up to its maximum speed, and the real communication speed will depend on the capabilities of the link partner advertised during the autonegotiation. On fiber interfaces, usually only a single speed is supported and it cannot be autonegotiated. This is because optical transceivers are usually constructed for only a single supported speed.

Best regards,
Peter

Joseph W. Doherty · ‎11-18-2015

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Posting

When port is up, it should indicate physical speed/bandwidth.

For example, from your original post:

Switch#sh interfaces fastEthernet 0/1
FastEthernet0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0019.56b4.cd03 (bia 0019.56b4.cd03)
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 00:01:59, 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 0 bits/sec, 0 packets/sec
5 minute output rate 1000 bits/sec, 1 packets/sec
77 packets input, 6737 bytes, 0 no buffer
Received 77 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 73 multicast, 0 pause input
0 input packets with dribble condition detected
142 packets output, 10954 bytes, 0 underruns
--More--

Masoud Pourshabanian · ‎11-18-2015

Adding to my previous comment.

It is the default output of show interface fa0/0

FastEthernet0/1 is up, line protocol is up (connected)

Hardware is Lance, address is 0060.4706.d201 (bia 0060.4706.d201)

MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Half-duplex, 100Mb/s

FastEthernet0/1 is up, line protocol is up (connected)

********************************************************************

I changed the speed of the interface from 100 to 10 by speed command. As you see, bandwidth is changed because bandwidth is calculated by speed; however, it is unrelated to the actual bandwidth. you can change it to 1 as I did in my previous comment. It does not have effect on actual bandwitdh.

Hardware is Lance, address is 0060.4706.d201 (bia 0060.4706.d201)

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

input flow-control is off, output flow-control is off

ARP type: ARPA, ARP Timeout 04:00:00

Masoud

Masoud Pourshabanian · ‎11-18-2015

Hello,

Bandwitdh and speed are different on the interface. Default bandwidth is calculated based on the interface speed or you can change it by "Bandwidth command" under the interface. BW does not have to do anything with actual bandwidth on the interface. Check the output below. I have changed bandwidth to 1, but still able to transfer much more on the interface. Check the 5 minutes input/output rate. It shows the current bandwitdh(average in 5 minutes).

FastEthernet0/0 is up, line protocol is up
Hardware is DEC21140, address is ca01.03c0.0000 (bia ca01.03c0.0000)
Internet address is 1.1.1.1/24
MTU 1500 bytes, BW 1 Kbit, DLY 100 usec,
     reliability 255/255, txload 204/255, rxload 204/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:03, output 00:00:03, 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 2135000 bits/sec, 201 packets/sec
5 minute output rate 2134000 bits/sec, 201 packets/sec
     106442 packets input, 155351022 bytes
     Received 20 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
     106540 packets output, 155356902 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets

Speed is the max speed that interface supoprts depending on the auto negotiation and BW is used for routing protocol to find the best path toward a destination.

Hope it helps,

Masoud