Slow speed when connecting to specific VLAN

[dgzbri]

Hi just want to ask if I have the same problem here and if you can share your solution.

We currently segregate our pc units to specific VLAN, we create a VLAN 550 where they can only access server but no internet access.
Upon our test run on 5 pc units, when opening an application, they experience a slow response from that application. While the other units that are connected to other VLAN have fast response. Is there anyone here with the same problem? We want to migrate those pc's to VLAN 550 but since we are experiencing slow response, we might not meet our timeline. Below is the interface of our VLAN 550.

SW-DC-CORE#sh int VLAN 550
Vlan550 is up, line protocol is up
 Hardware is Ethernet SVI, address is 
 Internet address is
 MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
   reliability 255/255, txload 1/255, rxload 1/255
 Encapsulation ARPA, loopback not set
 Keepalive not supported
 ARP type: ARPA, ARP Timeout 04:00:00
 Last input never, output 21:42:22, output hang never
 Last clearing of "show interface" counters never
 Input queue: 0/375/0/0 (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
   746674 packets input, 254138836 bytes, 0 no buffer
   Received 0 broadcasts (0 IP multicasts)
   0 runts, 0 giants, 0 throttles
   0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
   679223 packets output, 649123599 bytes, 0 underruns
   0 output errors, 4 interface resets
   0 unknown protocol drops
   0 output buffer failures, 0 output buffers swapped out

Thanks
dgzbri

[MHM Cisco World]

What is SW model?

MHM

[dgzbri]

Cisco C3850-nm-blank 24 port

[MHM Cisco World]

The interface connect to device use same mtu' can you do show interface 

MHM

[dgzbri]

@MHM Cisco World actually our vlans are configured inside our core c3850. mtu is 1500

[MHM Cisco World]

Show ip traffic statistics 

Check if there is any frag

MHM

[Gagandeep_Singh_1997]

can you share topology?

[Gagandeep_Singh_1997]

try same with creating new vlan

[g58211702 · Accepted solution]

• Bandwidth Limitation: Check if there are any bandwidth limitations set on VLAN 550. Since you mentioned that the speed is significantly slower compared to other VLANs, ensuring that the bandwidth allocation is appropriate for your applications is crucial.

• Quality of Service (QoS): Implement QoS settings to prioritize traffic on VLAN 550. This can help improve the performance of applications by ensuring they get the bandwidth they need over less critical traffic.

• Network Latency: Investigate if there are any network latency issues specifically affecting VLAN 550. Tools like ping tests or traceroute can help identify any delays in the network path.

• Application-Specific Issues: Verify if the applications being used have specific requirements for performance or connectivity that may not be being met by the VLAN configuration.

• Switch Configuration: Review the switch configuration for VLAN 550 to ensure that there are no misconfigurations. Pay attention to settings like STP (Spanning Tree Protocol) and ensure there are no blocked ports.

[timo-juhani · Accepted solution]

1) You're using SVI. Check for bottlenecks in LAN port speeds i.e. is there enough capacity even on theory. You didn't mention the device type of the software therefore for safety it makes sense to suggest that CPU load should be verified as well. Figure out if your traffic is for some reason hitting the CPU. This could be the case for the more "traditional" models.

2) Do you have a firewall between the VLANs? How does it perform?

3) Are the PCs distributing equal traffic load and type when you compare the two VLANs together?

[dgzbri]

Thank you for all your information.

I contacted the resigned network administrator of our company, and upon checking we have a bottleneck problem on vlan1 as what @timo-juhani said. Currently we are on-going check of what and who are connected to this vlan 1.

Thank you everyone, might as well give you feedback once we solve the bottleneck at vlan 1