Hi,

I have pix 535 with configured logical subinterfaces for each VLAN on my
network, so pix performes inter-VLAN routing. When I download a file (via
FTP) from machine in one VLAN to machine in other VLAN accross pix, speed of
download(upload) depends on the IP address I use on the machines. For
instance, when two PCs has following IP addresses:PC1:192.168.20.20, in VLAN
10, and PC2:172.16.20.20 in VLAN 20 (full duplex 100Mbit/s forced on switch
for both PCs), download speed is 0,8Mbit/s. When I just change the IP
address on PC1 to 192.168.20.21, download speed changes to 60Mbit/s. I have
similar problem in other network where RSM on Catalyst 5500 performes
inter-VLAN routing. Does anyone know what could be the problem?

Thanks in advence,

Vedran

In article <buqsgg$n47$1@ls219.htnet.hr>, vedran <vedran@hinet.hr> wrote:
:I have pix 535 with configured logical subinterfaces for each VLAN on my
:network, so pix performes inter-VLAN routing. When I download a file (via
:FTP) from machine in one VLAN to machine in other VLAN accross pix, speed of
:download(upload) depends on the IP address I use on the machines. For
:instance, when two PCs has following IP addresses:PC1:192.168.20.20, in VLAN
:10, and PC2:172.16.20.20 in VLAN 20 (full duplex 100Mbit/s forced on switch
:for both PCs), download speed is 0,8Mbit/s. When I just change the IP
:address on PC1 to 192.168.20.21, download speed changes to 60Mbit/s. I have
:similar problem in other network where RSM on Catalyst 5500 performes
:inter-VLAN routing. Does anyone know what could be the problem?

That's odd, but not impossible.

It is -plausible- that the internal processing is hashing upon the last
two octets of the IP address, and that the devices are having to do
extra work in case of a hash conflict. An interesting experiment would
be to change the destination to 172.160.20.21 and see if the speed
drops again.

I would expect the results to be more pronounced on the RSM, where
DMA would come into play. But then I don't know the RSM architecture well.
-- 
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