HP 5304Xl inter-vlans routing issue

[Marius_rg]

I think the reason you have to keep on doing a 'clear arp' is because you have an IP address conflict, both the 5300 and 2500 are using 10.20.10.33 on VLAN 20. You should remove this from the 2500.

Remove the IP fron the other switches ? And what ip address should I use for all vlans on the other switches??

On vlan1 I can't do any changes because this is the current vlan in witch are all servers,clients in the firm. And if I make something wrong ....

I don't want to use vlan1. After all the vlans are created then all the network will be on these vlans, no vlan1.
And, I removed the management vlan1...

[Matt Hobbs]

The 2500 doesn't really require an IP address on VLAN 20 at all. You can manage it from the VLAN 1 address.

If you do want an IP address on VLAN 20, then you need to use a unique address, maybe 10.20.10.34?

[Marius_rg]

So on the other switches I need only to have the vlans, with ip config DISABLED ??

And, for test I've removed the ip from all my vlans, but still I have to make an clear arp to make'it work, for a while :(

HP5304XL- ip route
Destination Gateway VLAN Type Sub-Type Metric Dist.
------------------ --------------- ---- --------- ---------- ---------- -----
10.20.10.0/24 DEFAULT_VLAN 1 connected 0 0
10.20.10.32/28 VLAN_VideoCA 20 connected 0 0
10.20.10.48/28 VLAN_EXTRA 30 connected 0 0
127.0.0.0/8 reject static 0 250
127.0.0.1/32 lo0 connected 0 0

[Marius_rg]

Everyting seems to be ok, but after a while, it stops routing.
If I clear arp is working, and then...NO

What is wrong ?

[Antonio Milanese]

Hello,

Matt Hobbs :
>I think the reason you have to keep on
>doing a 'clear arp' is because you have an
>IP address conflict, both the 5300 and 2500
>are using 10.20.10.33 on VLAN 20. You
>should remove this from the 2500.
good point..i've missed this one when i've read the configs!

Mohieddin Kharnoub:

sure yours observations are correct but i
still suggest to avoid subnet overlapping
at least if dont have a good reason to
summarize the routing tables or some other
needs.When i deal with ip addressing i'm
a big fan of KISS approach!

Marius_rg:

Well your routing table show the overlapping
entries i've told above..i really suggest
to adjust the subnet mask for VLAN 1.
Another observation is that port 25 on the
2500 as uplink trunk is member of both tagged VLANs and unttaged
VLAN 1: since the 2500 series has a
single istance forwarding database this
may cause problem with the overlapping
routing table aforementioned.

As suggested by Matt remove the duplicate ip
on the 2500 and if you still need to clear
the arp cache post those entries and
the table of MAC learned by each VLAN on
trunk port.

Best regards,

Antonio

[Marius_rg]

I've removed the ip address from the vlans on the other switch, but still I need to clear arp ( on the client, or on the switch )

How can I adjust subnetting on vlan1 without affecting my running network ?


====Well your routing table show the overlapping
entries i've told above..i really suggest
to adjust the subnet mask for VLAN 1.


Yes, port 25 is untagged on vlan1 and tagged on the other vlans. If I change from untagged into tagged on vlan1, it's not a problem with my network?

====Another observation is that port 25 on the
2500 as uplink trunk is member of both tagged VLANs and unttaged

Switch1-4thFL-HP5304XL(config)# show arp

IP ARP table

IP Address MAC Address Type Port
--------------- ----------------- ------- ----
10.20.10.1 003048-581ee4 dynamic D3
10.20.10.10 003005-99ebc2 dynamic D2
10.20.10.15 00123f-48f0b6 dynamic
10.20.10.143 0015f2-c460aa dynamic C3
10.20.10.246 001372-52365f dynamic C3
10.20.10.39 0015f2-3af5b6 dynamic B12
10.20.10.55 0013d4-c34d2f dynamic
10.20.10.63 0015f2-3af29c dynamic
10.20.10.66 0013d4-c34d46 dynamic
10.20.10.49 001438-748800 static
10.20.10.65 001438-748800 static


Switch 3 - ProCurve2524(config)# show arp

IP ARP table

IP Address MAC Address Type Port
--------------- ----------------- ------- ----
10.20.10.1 003048-581ee4 dynamic 25
10.20.10.15 00123f-48f0b6 dynamic 17
10.20.10.65 0015f2-47f1dc dynamic 25
10.20.10.143 0015f2-c460aa dynamic 9

Now I have a client on vlan 40 (ip 10.20.10.66 port 7 switch 2524)

[Matt Hobbs]

To rule out the chance that the overlapping subnet mask is causing a problem, I would create two new VLANs (2001,2011) on the 5300, 20.0.0.1/24 and 20.0.1.1/24. Tag C3 for these VLANs and create the same VLANs on the 2500, tagging port 25. Untag one port for VLAN 2001 on the 2500 and another port for 2011).

Connect your two clients to the 2500, give them 20.0.0.2/24 gw 20.0.0.1 and 20.0.1.2/24 gw 20.0.1.1.

Otherwise if you have a problem, capture a show arp, and when the problem has been resolved by clear arp, capture another show arp. It should become apparent what the problem is.

[Antonio Milanese]

How

>How can I adjust subnetting on vlan1 without affecting my running network ?
good question..if you have configured your devices according
to the ip address partitioning in your first message,
nothing bad should happen since each device has a non overlapping
network host address and gateway.
VLANs are layer 2 segmentations, when a device is plugged into
a f.e. untagged VLAN1 port it share the same L2 broadcast domain
as other VLAN1 members, the ip level is neutral to this
segmentation infact you can mix and match ip addr/subnets
within your VLAN, ofcourse you need a router to let each
one talk to others.
So if the ip configuration of a device that's "living"
within VLAN1 has an ip configuration like in your
vlan10- 10.20.10.0/27 and a gateway of 10.20.10.3
you can change the VLAN subnet to /27 without worries


In a L3 switch like the 5300 when you assign an ip addr to a VLAN
you've simply created a virtual interface that can route traffic
for that "ethernet virtual segment".
This virtual interface is obviusly not bounded to a specific
port but have its own MAC i.e. in the show arp you see those
entries:
10.20.10.49 001438-748800 static
10.20.10.65 001438-748800 static

> Yes, port 25 is untagged on vlan1 and tagged on the other vlans.
> If I change from untagged into tagged on vlan1, it's not a problem
> with my network?

The problem with single istance forwarding switch and
routing enabled is described in the chaper 2 of
Advanced Traffic Management manual.
When you think about how ARP work and what happen if
you have overlapping subnets in different VLANs maybe
you have a culprit for the ARP schizofrenia we see.

As suggested by Matt you can verify the problem creating
2 different VLAN with different network/gateway.

The suggestion to capture the ARP table before and after
the problem is another good one, i'll add a show mac
with the mac address of the stations too and try
to found any incongruence.

Best regards,

Antonio

[Matt Hobbs]

With the latest running-config that you attached a few posts ago, it looks as though VLAN1 is simply acting as a switch and is not actually being used as the default gateway for any clients.

There is no static route to the next hop device, and RIP is not enabled on VLAN1. Also your 'show ip route' is evidence of this.

I believe all your clients are probably pointing to 10.20.10.1.

So changing the subnet mask on VLAN 1 should not affect your production network.

[Marius_rg]

Hello guys, sorry for my absence. I was a little busy.
So, Iâ ve tested, as Matt Hobbs said, and it worked. It was like you all said, the overlapping subnet mask.
Now Iâ m trying to prepare for all vlans.
VLAN1, will exist no more, I mean that no used port will remain in that vlan, so I must move the primary vlan on VLAN_SERVERS ( ID80 ), and create VLAN_IT with ip 10.20.10.1 mask 255.255.255.224.
I will attach my running-config ( donâ t make notice of the ports, because I canâ t move them, only this weekend perhaps ) and I hope itâ s OK.
My default gateway to the internet will be on VLAN_SERVERS, ip 10.20.10.226.

Do I need anything else to make my vlans work?

Thank you all.