Re: VLAN problems

Alexandre Biancalana wrote:
Hi list,

I changed the company gateway implementing vlan concept and now I
have a lot of slow and packet loss.

I'm running FreeBSD FW1 7.0-PRERELEASE FreeBSD 7.0-PRERELEASE #0:
Fri Jan 25 10:36:18 UTC 2008 root@FW1:/usr/obj/usr/src/sys/FW
amd64

This server is an Dell Power Edge 1950, QuadCore 2.83, 2Gb Ram, one
bce gigabit interface connected to a gigabit port of a Cisco 4500 in
trunk mode. There are 10 vlans configured on top of bce1 interface. I
made this change last night and with small traffic all was ok, but
with the increase of the traffic during normal daily usage, we are
experiencing too much packet loss and slow connections.

I change the mtu of bce to 9000, this help something but I still
have bad performance. I think that this could be related with mtu, but
I don't know where and what to change.

I have seen some problems if you try to run more than one MTU on different VLANS with the same parent interface. For example if you set the parent interface MTU and vlan1 to 9000 and then tried to change vlan2 to have a 1500 byte mtu then the change of mtuon the vlan would also change the mtu on the parent.

If you are not running jumbo frames or nested vlans I don't think that changing the mtu of the interface is going to help you. The output of ifconfig would also help people give you more help with this.

Tom

Googling around I found some references that said to test mtu with
ping and here are the results:

# ping -D -s 1473 192.168.0.5
PING 192.168.0.5 (192.168.0.5): 1473 data bytes
ping: sendto: Message too long
ping: sendto: Message too long
--- 192.168.0.5 ping statistics ---
6 packets transmitted, 0 packets received, 100.0% packet loss

# ping -D -s 1400 10.2.0.36
PING 10.2.0.36 (10.2.0.36): 1400 data bytes
1408 bytes from 10.2.0.36: icmp_seq=0 ttl=64 time=86.026 ms
1408 bytes from 10.2.0.36: icmp_seq=1 ttl=64 time=5.558 ms
--- 10.2.0.36 ping statistics ---
3 packets transmitted, 2 packets received, 33% packet loss
round-trip min/avg/max/stddev = 5.558/45.792/86.026/40.234 ms


Looking at netstat -ni output I have output errors too:

# netstat -niW
Name Mtu Network Address Ipkts Ierrs Opkts
Oerrs Coll
bce0* 1500 <Link#1> 00:1d:09:67:8d:f1 0 0 0
0 0
bce1 9000 <Link#2> 00:1d:09:67:8d:ef 83289870 0 80535996
0 0
pflog0 33160 <Link#3> 0 0 1153529
0 0
lo0 16384 <Link#4> 516657 0 516661
0 0
lo0 16384 127.0.0.0/8 127.0.0.1 4041401 - 516661
- -
pfsync0 1460 <Link#5> 0 0 0
0 0
vlan2 1500 <Link#6> 00:1d:09:67:8d:ef 37445062 0 32727529
1047565 0
vlan2 1500 10.2.0.0/16 10.2.0.36 636786 - 3000823
- -
vlan11 1500 <Link#7> 00:1d:09:67:8d:ef 33865371 0 36676651
993848 0
vlan11 1500 10.11.0.0/16 10.11.0.1 51270 - 1147250
- -
vlan16 1500 <Link#8> 00:1d:09:67:8d:ef 388 0 19
0 0
vlan16 1500 10.16.0.0/24 10.16.0.1 5 - 13
- -
vlan20 1500 <Link#9> 00:1d:09:67:8d:ef 1483 0 1
0 0
vlan20 1500 10.20.0.0/24 10.20.0.1 636 - 0
- -
vlan200 1500 <Link#10> 00:1d:09:67:8d:ef 390 0 3
0 0
vlan200 1500 10.200.0.0/30 10.200.0.1 0 - 0
- -
vlan201 1500 <Link#11> 00:1d:09:67:8d:ef 19153 0 19274
3408 0
vlan201 1500 10.200.0.4/30 10.200.0.5 0 - 0
- -
vlan202 1500 <Link#12> 00:1d:09:67:8d:ef 8338 0 6694
1074 0
vlan202 1500 10.200.0.8/30 10.200.0.9 0 - 0
- -
vlan203 1528 <Link#13> 00:1d:09:67:8d:ef 1691886 0 1429174
86768 0
vlan203 1528 192.168.0.0/2 192.168.0.1 35672 - 31375
- -
vlan204 1500 <Link#14> 00:1d:09:67:8d:ef 1256 0 3
0 0
vlan204 1500 10.0.0.84/30 10.0.0.85 0 - 0
- -
vlan205 1500 <Link#15> 00:1d:09:67:8d:ef 10256373 0 9676750
626525 0
vlan205 1500 10.0.0.8/30 10.0.0.9 2509909 - 2667896
- -


Any help is very appreciated,

Regards,
Alexandre Biancalana

PS: Please cc me, because I'm not subscribed in the list.
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