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New Member

Packet Loss on Catalyst

Hello Community,

I have recently tried implementing a Catalyst L3 into my network acting as an internal router between 4 subnets.

Once I implmeneted, I noticed that there were lots of packet latency and dropped packets. I was losing connections to servers even. When I pinged those subnets, I noticed latency up to 900ms.

I have this catalyst connected to dell powerconnect switches which I think may be the issue.

Is there some specific parameters I need to enable/disable on a port that connects to another switch?

My powerconnect ports are set to auto negotiate. My catalyst is set at 100M with spanning-tree portfast enabled.

thanks in advance

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: Packet Loss on Catalyst

Is the latency between the vlans all excessive.

What is the ping times from a client to the L3 switch?

Have you checked the CPU and memory usage on the switch?

Sent from Cisco Technical Support iPhone App

12 REPLIES
Green

Packet Loss on Catalyst

Try a "show int status" on the catalyst, check if any of the ports are running 10Mb or half duplex.

New Member

Re: Packet Loss on Catalyst

Hi acomiskey,

Thanks for the reply.

I have disconnect the other 3 cables, but one is still connected.

I had the other 3 cables plugged into port 0/1 - 0/3

Fa0/1                        notconnect   2            auto   auto 10/100BaseTX

Fa0/2                        notconnect   3            auto   auto 10/100BaseTX

Fa0/3                        notconnect   4            auto   auto 10/100BaseTX

Fa0/4                        connected    5          a-full  a-100 10/100BaseTX

Fa0/5                        notconnect   1            auto   auto 10/100BaseTX

Fa0/6                        notconnect   1            auto   auto 10/100BaseTX

Fa0/7                        notconnect   1            auto   auto 10/100BaseTX

Fa0/8                        notconnect   1            auto   auto 10/100BaseTX

Fa0/9                        notconnect   1            auto   auto 10/100BaseTX

Fa0/10                       notconnect   1            auto   auto 10/100BaseTX

Fa0/11                       notconnect   1            auto   auto 10/100BaseTX

Fa0/12                       notconnect   1            auto   auto 10/100BaseTX

Fa0/13                       notconnect   2            auto   auto 10/100BaseTX

Fa0/14                       notconnect   2            auto   auto 10/100BaseTX

Fa0/15                       notconnect   2            auto   auto 10/100BaseTX

Fa0/16                       notconnect   2            auto   auto 10/100BaseTX

Fa0/17                       notconnect   3            auto   auto 10/100BaseTX

Fa0/18                       notconnect   3            auto   auto 10/100BaseTX

Fa0/19                       notconnect   3            auto   auto 10/100BaseTX

Fa0/20                       notconnect   3            auto   auto 10/100BaseTX

Fa0/21                       notconnect   4            auto   auto 10/100BaseTX

Fa0/22                       notconnect   4            auto   auto 10/100BaseTX

Fa0/23                       notconnect   4            auto   auto 10/100BaseTX

Fa0/24                       notconnect   4            auto   auto 10/100BaseTX

Gi0/1                        notconnect   1            auto   auto Not Present

Gi0/2                        notconnect   1            auto   auto Not Present

This command may help:

arisrouter#show interface fastethernet 0/4 switchport

Name: Fa0/4

Switchport: Enabled

Administrative Mode: static access

Operational Mode: static access

Administrative Trunking Encapsulation: negotiate

Operational Trunking Encapsulation: native

Negotiation of Trunking: Off

Access Mode VLAN: 5 (VLAN0005)

Trunking Native Mode VLAN: 1 (default)

Administrative Native VLAN tagging: enabled

Voice VLAN: none

Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk Native VLAN tagging: enabled

Administrative private-vlan trunk encapsulation: dot1q

Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled

Capture VLANs Allowed: ALL

Protected: false

Unknown unicast blocked: disabled

Unknown multicast blocked: disabled

Appliance trust: none

arisrouter#

Thanks

John

New Member

Re: Packet Loss on Catalyst

Hi John

Can you post the results from show interface fa0/4. Also can you post the show interface from the Dell switch.

Also, take off spanning-tree portfast.

Sent from Cisco Technical Support iPhone App

New Member

Re: Packet Loss on Catalyst

Hello Fergua,

Here are my results:

arisrouter#sh interface fastethernet 0/4

FastEthernet0/4 is up, line protocol is up (connected)

  Hardware is Fast Ethernet, address is 0007.0e76.0c86 (bia 0007.0e76.0c86)

  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 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

     460707 packets input, 63684643 bytes, 0 no buffer

     Received 34257 broadcasts (0 multicasts)

     0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 31404 multicast, 0 pause input

     0 input packets with dribble condition detected

     893037 packets output, 183463100 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

I could not get the command line on my dell powerconnect, but I have attached a screen shot of the g33 ethernet port I connected to.

So now my interfaces look like this without the spanning-tree portfast:

interface FastEthernet0/1

switchport access vlan 2

switchport mode access

!

interface FastEthernet0/2

switchport access vlan 3

switchport mode access

!

interface FastEthernet0/3

switchport access vlan 4

switchport mode access

!

interface FastEthernet0/4

switchport access vlan 5

switchport mode access

New Member

Re: Packet Loss on Catalyst

Is the latency between the vlans all excessive.

What is the ping times from a client to the L3 switch?

Have you checked the CPU and memory usage on the switch?

Sent from Cisco Technical Support iPhone App

New Member

Re: Packet Loss on Catalyst

Hi Fergus,

Yes. latency is excessive when pinging. Times were reaching 800ms pinging from one network to another.

I did not check the CPU or the memory useage on the L3.

This is the CPU and RAM I have:

cisco WS-C3560-24TS (PowerPC405) processor (revision E0) with 122880K/8184K bytes of memory.

New Member

Re: Packet Loss on Catalyst

Are you still getting high ping times to the L3 switch vlan interfaces, rather than pinging across the vlans.

Also if you have 2 devices on the same vlan on the switch, what is the response times between these two devices?

Sent from Cisco Technical Support iPhone App

New Member

Re: Packet Loss on Catalyst

I took out my L3 router and re-commissioned my old Linux router until I get things staightened out.

When the L3 was active, I did not try to ping to the direct VLAN ip address, I only tried pinging across the vlans. This is where I noticed the large amounts of latency and few dropped packets during the constant ping

I did have a constant ping to another server within the same vlan. Those pings were all 100% successful unlike the across vlan pings.

New Member

Re: Packet Loss on Catalyst

Do you think my Catalyst could be broken?

I just do not understand all the latency and dropped packets.

I still need to test tuning the Dell Powerconnect port to 100M and disabling auto. Then connect that port to the 100M port on the Catalysy.

Can you think of anything else I can test?

New Member

Re: Packet Loss on Catalyst

Hello,

I just put the catalyst L3 into production again. I am hoping that making all the ports 100m will help. I have a constant ping to my direct VLAN and to another server across the VLAN.

I see it is still spotty meaning that pinking both direct VLAN IP adddres and across is resulting in some latency. Every 10-20th packet has latency up to 10ms. All other packets are <1ms.

I am crossing my fingers, but not hopeful since is some latency.

New Member

Re: Packet Loss on Catalyst

Knowing nothing about traffic.....just trowing it out there, could latency be due to iSCSi traffic? I have a server who uses 5 different microsoft iSCSi initiators.

Maybe the L3 cannot handle the traffic?

But that server who uses the iSCSi san, is on the same subnet....so it would not really use the L3 to go across VLANs....

New Member

Re: Packet Loss on Catalyst

Yes I now see the Dell Powerconnect does not have jumbo frames enabled, but the switch has global parameters:

iSCSi status: Enabled

CoS: 5

Remark: Enabled

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