Re: One direction Bandwidth Issue

sajidabbas · ‎05-19-2019

Hi,

We are having an issue where bandwidth obtained in one direction is quite low as compared to the other direction.

We have done iperf/jperf and also SMB testing in both direction which seems to be giving the same consistent results.

We have the following topology

Station A <-> 6800 <-> 4900M <-> Station B

Station A to B = 50% speed

Station B to A = Full speed

I have seen some other posts similar to this but without any solution.

Anybody can shed light or assist on this.

Sajid

Seb Rupik · ‎05-19-2019

Hi there,

Do you have QoS implemented in this topology?

If so, it could be that traffic from station B is being marked on ingress into the network and receiving preferable policing along the path to station A.

Station A's traffic on ingress is being placed in the default queue and suffering as a result.

cheers,

Seb.

sajidabbas · ‎05-20-2019

We do have QoS implemented but have taken it off to do the testing.

I have done some wiresharking and dont see any marking in the packets going through the network.

How to verify on the switch if marking is being done.

Georg Pauwen · ‎05-19-2019

Hello,

what is Station A and what is Station B (e.g. are these 'regular' Windows machines) ? We need to see the output of 'show interfaces x' where 'x' are the interfaces of respectively the 6800 and the 4900 switches the stations are connected to...

sajidabbas · ‎05-20-2019

Station A and B are win10 machines.

show interface outputs as shown below

Station A
GigabitEthernet105/1/0/26 is up, line protocol is up (connected)
Hardware is C6k 1000Mb 802.3, address is 689c.e2e8.7a9a (bia 689c.e2e8.7a9a)
MTU 9216 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is 10/100/1000BaseT
input flow-control is off, output flow-control is unsupported
Clock mode is auto
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:21, output never, output hang never
Last clearing of "show interface" counters 1y47w
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 35962
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 2957000 bits/sec, 269 packets/sec
5 minute output rate 378000 bits/sec, 97 packets/sec
387476361 packets input, 289876840624 bytes, 0 no buffer
Received 1730602 broadcasts (1589183 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 251658240 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
790061723 packets output, 754747609160 bytes, 0 underruns
0 output errors, 0 collisions, 4 interface resets
0 unknown protocol drops
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

Station B
GigabitEthernet3/9 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet Port, address is 0026.991f.dfff (bia 0026.991f.dfff)
Description: To-TVCRTR1 Gi3/12
Internet address is 172.25.1.129/30
MTU 9198 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseT
input flow-control is on, output flow-control is on
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:04:32, output never, output hang never
Last clearing of "show interface" counters 21:13:49
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 0 bits/sec, 0 packets/sec
30 second output rate 1000 bits/sec, 1 packets/sec
L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
L3 out Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
IPv6 L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
IPv6 L3 out Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
3111757 packets input, 2947831277 bytes, 0 no buffer
Received 1299 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 input packets with dribble condition detected
2407785 packets output, 3066572668 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

Seb Rupik · ‎05-21-2019

Hi there,

The overrun value on the Station A interface would indicate traffic loss A -> B :

251658240 overrun

...is station A connected to a FEX? What software version are you running on the 6800?

cheers,

Seb.

Giuseppe Larosa · ‎05-21-2019

Hello Sajid,

>> GigabitEthernet105/1/0/26 i

are you using Instant access with FEX like dependent modules / satellite switches?

In first implementation of instant access unicast traffic needs to go up to master C6800 to be routed.

In other words Instant access with C6800 and its satellite devices is only suited for access devices not to host servers that may need better performance.

Hope to help

Giuseppe

Georg Pauwen · ‎05-21-2019

Hello,

the flow control settings on both interfaces differ, not sure if that makes a difference, you might want to make sure the settings match (interface command 'flowcontrol receive off/on')...

Station A
GigabitEthernet105/1/0/26 is up, line protocol is up (connected)
Hardware is C6k 1000Mb 802.3, address is 689c.e2e8.7a9a (bia 689c.e2e8.7a9a)
MTU 9216 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is 10/100/1000BaseT
input flow-control is off, output flow-control is unsupported

Station B
GigabitEthernet3/9 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet Port, address is 0026.991f.dfff (bia 0026.991f.dfff)
Description: To-TVCRTR1 Gi3/12
Internet address is 172.25.1.129/30
MTU 9198 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseT
input flow-control is on, output flow-control is on