high latencies on routing interface on Powerconnect 6248

Can you post the specific config of the Layer 3 interfaces of the two VLANs.....as this sounds very odd.

How many client PC or hosts do you have in each VLAN...is it a classic /24 subnet with typically 250 hosts ?

If you have a very large client PC base in a single VLAN.....i.e 500+ then you could have ARP or DHCP broadcasts on initial bootup causing problems - but not when logging off.

Hello

Thank you very much for your answer

In one lan i have 200 clients aprox and in other 50

This is the config file:

'-----------------------------------------------------------------------------------

!Current Configuration:
!System Description "Dell 48 Port Gigabit Ethernet, 2.1.0.13, VxWorks5.5.1"
!System Software Version 2.1.0.13
!
configure
vlan database
vlan  2-3
vlan association subnet x.x.x.x 255.255.255.0 2
vlan association subnet y.y.y.y 255.255.255.0 3
exit
stack
member 1 2
exit
ip address 192.168.50.5 255.255.255.0
ip routing
ip route 0.0.0.0 0.0.0.0 x.x.x.237
router rip
no enable
exit
interface vlan 2
name "LAN_xxx"
routing
ip address  x.x.x.254  255.255.255.0
no ip proxy-arp
exit
interface vlan 3
name "LAN_yyy"
routing
ip address  y.y.y.254  255.255.255.0
no ip proxy-arp
exit
username "admin" password xxxxxxxxxxxxxxxxxxxxxxxxxx level 15 encrypted
router ospf
no enable
no 1583compatibility
exit
!
interface ethernet 1/g3
switchport access vlan 2
exit
!
interface ethernet 1/g4
switchport access vlan 2
exit
!
...
!
interface ethernet 1/g24
switchport access vlan 2
exit
!
interface ethernet 1/g25
switchport access vlan 3
exit
!
...
!
interface ethernet 1/g48
switchport access vlan 3
exit
exit

'--------------------------------------------------------------------

Thank you very much

For yor logon issue could i suggets you use this command on each PC /host interface :

 interface ethernet 1/g3

 spanning-tree portfast

By enabling port-fast on each user PC port you will skip the listening learning stages of Spanning tree and go straight to forwarding of

packets.

If you enable port-fast on each of the PC ports, be careful about connecting other switches to those ports or causing a loop in your network.  Port fast effectively disables the benefits of Spanning Tree.  But I agree with Sentinel-master, you will see a decrease in the amount of time it takes before each of your PCs are able to send and receive packets when the NIC links up initially.

But I have a feeling that the type of latency that you're talking about might be different.  Can you give a hypothetical scenario that describes your problem?  When you're seeing packet loss, are you seeing that on the host computers when doing pings or is your switch showing something indicating dropped packets or errors in its counters?

One other thought I had related to PCs, is the default gateway, just want to check this piece of information from you.

How have you assigned IP addresses to your PC hosts....is it via DHCP or static IP addressing.

Either way what is the default IP gateway address of teh PC hosts ?

.....is it the LAN IP address of the L3 switch interface ?

Hello tester25

Thank you for your answer

I see the packet loss when i do a ping from one vlan1 computer to one vlan2, if i do a ping from vlan1 to vlan1 or vlan2 to vlan2 there is not packet loss.

Hello sentinel-master

Thank you very much for your answer

I have DHCP in each vlan. and the gateway for pcs is the vlan ip interface for each vlan.

Regards

Okay that all makes sense -just wanted to make sure there was no other Layer hop or device involved.

Just to test a theory can you do a ping from PC_VLan 2  to PC_VLAN_3 and vice versa - whats the results ?

Avoid ping or using VLAN1 - as I want to see if the default management VLAN is related to loss.

This is bad news and is either a firmware bug - or the Layer 3 forwarding performance (between different VLANs) is getting hammered for soem reason.

I noticed in your config you have both RIP & OSPF enable - do you need both these enabled at the same time, could you turn one or both  off just to chekc CPU performance and interface forwarding without them in config.

hello sentinel-master

RIP and OSPF are disabled (no enable)

and the firmware, i tried with a backup switch 6248 with the last firmware, after this problem, and the result is the same. :(

Thank you very much

Regards

I also have the same problem so I hope someone can answer this. I also found out that if I enable portfast on a port then I can plug something into that port and it will not cause a problem but I would have to enable portfast on every port which doesn't seem right to me since portfast effectively disables what Spanning Tree was designed to do. There must be another answer.

I am also experiencing symptoms much like this, I would be interested to know if this has been solved or not... My Network sees the high latencies throughout the day. It is very random but seems to happen 100 + times a day. I can tell you that pings to devices on the same VLAN are fine...come back all <1ms. The latencies are across the VLANS. When I have a running ping to a device on a differnt VLAN I see high ping spikes several times an hour. Sometimes resulting in timeouts.

Also like I said pings on the same VLAN are fine, but when I ping to the VLAN gateway IP...Result is high ping spikes...

Thanks all...

Please post your confguration file.

Also, when the problem is occuring, execute the following command and post the output:

console# show process cpu

Here is the config of the 6224's

corpgate11#show run
!Current Configuration:
!System Description "Dell 24 Port Gigabit Ethernet, 2.1.0.13, VxWorks5.5.1"
!System Software Version 2.1.0.13
!
configure
vlan database
vlan  4,10,200,300,400,2000
exit
hostname "corpgate11"
stack
member 1 1
exit
ip address 192.168.2.2 255.255.255.0
ip address vlan 2000
ip domain-name alcpartner.com
ip name-server 192.168.0.8
ip name-server 192.168.0.9
ip routing
ip route 172.16.0.0 255.255.252.0 172.16.40.1
ip route 172.16.0.0 255.255.252.0 172.16.252.3
ip route 172.16.24.0 255.255.252.0 172.16.252.3

ip route 172.16.40.0 255.255.252.0 172.16.252.3
ip route 172.16.40.0 255.255.252.0 172.168.252.3
ip route 0.0.0.0 0.0.0.0 172.16.4.1
ip route 172.16.252.0 255.255.255.248 172.16.252.3
ip route 172.16.8.0 255.255.252.0 172.16.252.3
bootpdhcprelay enable
bootpdhcprelay serverip 192.168.0.8
interface vlan 1
routing
ip address  192.168.0.2  255.255.255.0
exit
interface vlan 4
name "corporate"
routing
ip address  172.16.4.2  255.255.252.0
exit
interface vlan 10
routing
ip address  172.16.252.2  255.255.255.248
exit
interface vlan 200

name "Accounting"
routing
ip address  172.16.28.2  255.255.252.0
exit
interface vlan 300
name "Marketing"
routing
ip address  172.16.24.2  255.255.252.0
exit
interface vlan 400
name "HR"
routing
ip address  172.16.36.2  255.255.252.0
exit
username "alcadmin" password e01e13231596db53b02df7457b4efbfd level 15 encrypted
!
interface ethernet 1/g1
switchport access vlan 4
exit
!
interface ethernet 1/g2

switchport access vlan 4
exit
!
interface ethernet 1/g3
switchport access vlan 10
exit
!
interface ethernet 1/g4
switchport access vlan 4
exit
!
interface ethernet 1/g5
switchport access vlan 4
exit
!
interface ethernet 1/g6
switchport access vlan 4
exit
!
interface ethernet 1/g8
switchport access vlan 4

exit
!
interface ethernet 1/g9
switchport access vlan 4
exit
!
interface ethernet 1/g10
switchport access vlan 4
exit
!
interface ethernet 1/g11
switchport access vlan 4
exit
!
interface ethernet 1/g12
switchport access vlan 4
exit
!
interface ethernet 1/g14
switchport access vlan 4
exit

!
interface ethernet 1/g15
switchport access vlan 4
exit
!
interface ethernet 1/g16
switchport access vlan 4
exit
!
interface ethernet 1/g18
switchport access vlan 4
exit
!
interface ethernet 1/g20
switchport access vlan 4
exit
!
interface ethernet 1/g21
switchport mode general
no switchport general acceptable-frame-type tagged-only
switchport general allowed vlan add 4,10,200,300,400 tagged

exit
snmp-server community public rw ipaddress 192.168.0.2
exit

These are the results of the show process cpu, First one is during the time with high latencies, The second one is during normal times and the third is once again during high latencies. I notice right away that the IpMapForwardingTask is high when the problems occur.

corpgate11#show process cpu

Memory Utilization Report

Status      Bytes
------ ----------
  Free   49901168
 Alloc  146315280

Task Utilization Report

Task                    Utilization
----------------------- -----------
osapiTimer                    1.30%
bcmL2X.0                      0.85%
bcmCNTR.0                     0.25%
bcmTX                         1.10%
bcmLINK.0                     0.85%
bcmRX                         4.55%
USL Task                      0.25%
MAC Send Task                 0.10%
MAC Age Task                  0.05%
dtlTask                       0.80%
hapiRxTask                    1.00%
hapiL2AddrFlushTask           0.15%
hapiRtAsyncTask               0.90%
dot1s_timer_task              0.15%
dot1s_task                    0.20%
radius_timer_task             0.05%
ipMapForwardingTask          18.90%
tL7Timer0                     0.05%
tArpCallback                  0.20%
Kernel/Interrupt/Idle        68.30%

Total                        100.00%

corpgate11#
corpgate11#
corpgate11#show process cpu

Memory Utilization Report

Status      Bytes
------ ----------
  Free   49890848
 Alloc  146325600

Task Utilization Report

Task                    Utilization
----------------------- -----------
osapiTimer                    1.10%
bcmL2X.0                      0.75%
bcmCNTR.0                     0.30%
bcmLINK.0                     0.55%
bcmRX                         0.75%
MAC Send Task                 0.05%
dtlTask                       0.05%
hapiRxTask                    0.25%
dot1s_timer_task              0.40%
dot1s_task                    0.05%
ipMapForwardingTask           0.80%
tL7Timer0                     0.05%
tArpCallback                  0.05%
Kernel/Interrupt/Idle        94.85%

Total                        100.00%

corpgate11#show process cpu

Memory Utilization Report

Status      Bytes
------ ----------
  Free   49890848
 Alloc  146325600

Task Utilization Report

Task                    Utilization
----------------------- -----------
osapiTimer                    1.30%
bcmL2X.0                      0.70%
bcmCNTR.0                     0.30%
bcmTX                         2.15%
bcmLINK.0                     0.60%
bcmRX                         5.80%
USL Task                      0.25%
envMonTask                    0.05%
dtlTask                       0.55%
hapiRxTask                    1.10%
hapiL2AddrFlushTask           0.30%
hapiRtAsyncTask               0.95%
RMONTask                      0.10%
dot1s_timer_task              0.15%
dot1s_task                    0.20%
ipMapForwardingTask          25.35%
tL7Timer0                     0.05%
tArpCallback                  0.35%
lldpTask                      0.05%
Kernel/Interrupt/Idle        59.70%

Total                        100.00%

Thanks for any help....