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high latency and packet loss in lan
hi,
im using 2 cisco 3560e Giga, with 4 etherchannel uplinks with vpan trunks, configured with hsrp on of the switches is active for all vlan ( i have 4 vlans).
i have 3 esx servers connected on both equipments for the HA.
Since a few time i have some packets lost if i ping between 2 machines in the same vlan or different vlan, the latency is minimum 1 ms average 2 ms and maximum 34 ms for repeat count of 1000 packets
the ping with maximum size make too much losts !!!
so any one have a suggestion ?
im using 2 cisco 3560e Giga, with 4 etherchannel uplinks with vpan trunks, configured with hsrp on of the switches is active for all vlan ( i have 4 vlans).
i have 3 esx servers connected on both equipments for the HA.
Since a few time i have some packets lost if i ping between 2 machines in the same vlan or different vlan, the latency is minimum 1 ms average 2 ms and maximum 34 ms for repeat count of 1000 packets
the ping with maximum size make too much losts !!!
so any one have a suggestion ?
Who is Participating?
hello giltjr
here is a sample of a ping
ping 10.10.10.52 repeat 1000 size 1800
Type escape sequence to abort.
Sending 1000, 1800-byte ICMP Echos to 10.10.10.52, timeout is 2 seconds:
!!!!!!!!.!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!.!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!
Success rate is 99 percent (994/1000), round-trip min/avg/max = 1/8/151 ms
Well, although I would expect 100%, 6 dropped packets out of 1000 is not that bad.
What is your MTU? Have you enabled jumbo frames?
You are using 1800 bytes. The default LAN MTU is 1500 bytes. If you have the default then you are fragmenting every packet.
If you want to test without fragmenting you need to specify 1472 instead of 1800, unless of course you have jumbo frame enabled. If you have jumbo frames you need to specific "MTU-28" (IP and ICMP headers are 28 bytes together).
What happens if you do not specify a size and let it default?
What is your MTU? Have you enabled jumbo frames?
You are using 1800 bytes. The default LAN MTU is 1500 bytes. If you have the default then you are fragmenting every packet.
If you want to test without fragmenting you need to specify 1472 instead of 1800, unless of course you have jumbo frame enabled. If you have jumbo frames you need to specific "MTU-28" (IP and ICMP headers are 28 bytes together).
What happens if you do not specify a size and let it default?
hello giltjr
My MTU is the standard one 1500.
No im not using jumbo frames so should i ?
when i do not specify the size, i have 0% of loss and the maximum latency time is reducing
My MTU is the standard one 1500.
No im not using jumbo frames so should i ?
when i do not specify the size, i have 0% of loss and the maximum latency time is reducing
Well, although I would expect 100%, 6 dropped packets out of 1000 is not that bad.I would disagree, any amount of packet loss is bad, especially utilizing TCP. Any packet loss is considered to be the result of network congestion and the congestion window size is reduced dramatically as a precaution. Your packet loss could be a result of many different factors and without some detailed troubleshooting and information, we will not be able to assist, we would only be assuming. please provide the configuration of your 2 switches, ensure that your port descriptions on configured on the ports so that we can identify what NICs are connected to what ports. Also, provide some screen shots on the vswitch configuration.
just as a test to rule on multihoming issues, remove NIC 2, and retest with 1800 bytes and report back.
Billy
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As I stated before, going larger than what a single Ethernet frame (MTU) causes fragmentation. Once you have fragmentation there are other issues that can cause lost packets.