stacking 3 procurve 2510 and using vlan

[Frederick Natividad]

I have 3 procurve 2510 connected in series via fiber like this.

A <--fb--> B <--fb--> C

i have a a.b.c.d subnet connected to A, and two more machines using the same subnet connected to C. is it possible to stack the 3 procurve and define a vlan to isolate subnet a.b.c.d from the other subnet?

thanks.

P.S. This thread has been moved from Switches, Hubs, Modems (Legacy ITRC forum) to  ProCurve / ProVision-Based. -HP Forum Moderator

[Pieter 't Hart · Accepted solution]

the term "stack" does not apply here.

If you want totally separate networks, then this should be no problem.
If you are using vlan100 on switches A, B and C; and vlan200 on switches A and C, then the only thing you need to do is let switch-B NOT know about vlan 200!
The interconnecting ports A <-> B and B <-> C should NOT pass vlan200!
=> don't configure these ports either tagged or untagged for vlan200.
So switch-B won't provide a (virtual) link between the two VLAN200's.

Allthough the same vlan-number (200) and subnets are used they remain separate networks.

Only if you DO want some traffic between VLAN100 and VLAN200 then there will be a problem to determine if data must be sent to vlan200-a or vlan200-b.

To avoid problems in the future I would consider to renumber one of the subnets.

[Frederick Natividad]

thanks pieter for the reply.

im a newbie in vlan configs, and i thought stack will do the trick. your reply was very informative and helpful for me.

but i still doesnt understand what you mean by saying that one vlan should not pass the other vlan.

at this point, i am still confused on tagging and untagging and trunking, and so i really dont know how to configure my procurve to connect my host from switch A to host in switch C without other hosts knowing it.

thanks a lot.

[Pieter 't Hart]

Hi Frederick
>>> but i still doesnt understand what you mean by saying that one vlan should not pass the other vlan <<<
No I didn't say that.

I said, the SWITCH "in the middle" (switch-b) should not pass the unwanted vlan from left (switch-a) to right (switch-c).

lets' start at a single switch.
You create three vlan's on this switch (100, 200, 300).
(switch-A)
vlan 100
untagged 1 - 5
exit
vlan 200
untagged 6-10
exit
vlan 300
untagged 11-15
exit

Vlans are used to separate networks like physically separate networks, so there is no data exchanged between the three vlan's/subnets!
ports 1-5 cannot communicate with ports 6-10.

You need a coupling device (a router) that knows about the vlan/s and subnets to transfer data between them.
Some switches can do the routing function internally so you don't need an extra physical device, but from IP-networking view it's a separate function (device).

Now you add a second switch.
(switch-A)
vlan 100
untagged 1 - 5
tagged 24
exit
vlan 200
untagged 6-10
tagged 24
exit
vlan 300
untagged 11-15
exit
(switch-B)
vlan 100
untagged 1 - 5
tagged 24
exit
vlan 200
untagged 6-10
tagged 24
exit
vlan 300
untagged 11-15
exit
connected the switches using port-24

packets from swich-a vlan-100 can reach all untagged ports on switch-a (offcourse).
if they need to go to the other switch, a vlan-tag is added to the packet and sent through port-24.
switch-b recognizes it's for vlan100 removes the tagg and can send it to the local untagged ports in vlan-100.
so switch-a/port-1 to 5 can communicate to switch-b/port-1 to 5.

Same goes for vlan-200 ports 6 to 10.

But NOT for vlan300!
packets are not sent (tagged or untagged) via port-24 to switch-b.
so vlan300 on switch-a stays separate from vlan300 on switch-b.

This looks like the configuration you requested, but you need a third switch;
vlan300 does not need to exist on the middle switch at all!

(switch-A)
vlan 100
untagged 1 - 5
tagged 24
exit
vlan 200
untagged 6-10
tagged 24
exit
vlan 300
untagged 11-15
exit
(switch-B)
vlan 100
untagged 1 - 5
tagged 23,24
exit
vlan 200
untagged 6-10
tagged 23,24
exit
(switch-C)
vlan 100
untagged 1 - 5
tagged 23
exit
vlan 200
untagged 6-10
tagged 23
exit
vlan 300
untagged 11-15
exit
connect switch-a/port-24 to switch-b/port-24
connect switch-c/port-23 to switch-b/port-23

so switch-a/port-1 to 5 can communicate to switch-b/port-1 to 5 and to switch-c port 1 to 5
Same goes for vlan-200 ports 6 to 10.
switch-a ports 11-15 can NOT communicate witch switch-c ports 11-15 as desired.

all switches/port-1 to 5 canNOT communicate with ports-6 to 10; you need to add a router to make that possible.

[Frederick Natividad]

sir pieter,

thanks a lot!
what a very informative detailed step.

that solved my problem

[FrankK3]

Pieter 't Hart,

Could the routing be turned on by adding "IP Routing" to the running-config and enabling RIP?