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Webcast-Catalyst9k
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HP Switch connected to Cisco Device Issue

I have an HP switch layer 2 connected to a Cisco switch layer 3 and have the following issues. The HP used to go to another HP with no issues the Cisco device is new. I beleive I'm missing something easy but have no experience going from HP to Cisco.

The HP setup is very basic  I've posted most of it below. The problem is from the Cisco device I can ping vlan 93's IP address and from the HP I can ping vlan 93's gateway on the Cisco device. Either from the HP or Cisco can I ping the IP address of vlan 11. The IP gateway of the HP is a valid IP on the Cisco device and from the HP I cannot ping this gateway. From outside of my building I cannot ping the IP address of vlan 73. I've included what the port config looks like on the Cisco device below.

Thanks for any input you can provide!

hostname "XX"

snmp-server mib hpSwitchAuthMIB excluded

time timezone -5

no web-management

web-management ssl

interface 48

   name "user"

exit

interface 49

   name "UplinkfromCore"

exit

trunk 49 Trk1 Trunk

ip default-gateway 10.x.x.x

logging facility local1

logging x.x.x.x

vlan 11

   name "Servers"

   untagged 2,10,50-52

   ip address 10.x.x.x 255.255.255.0

   tagged Trk1

   no untagged 1,3-9,11-48

   exit

vlan 128

   name "users"

   untagged 46-48

   tagged Trk1

   exit

vlan 26

   name "Voice"

   no ip address

   qos priority 6

   tagged 1-9,11-48,Trk1

   voice

   exit

vlan 93

   name "Data"

   untagged 1,3-9,11-45

   ip address 10.X.X.X 255.255.255.0

   tagged Trk1

   exit

Here is  the ports config on the Cisco device

interface GigabitEthernet1/0/46

description *** Uplink to HP ***

switchport mode trunk

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Blue

HP Switch connected to Cisco Device Issue

Derek

On HP's if I have mulitlple vlans as long as I turn on IP routing and point them to a router or L3 switch I should be able to setup mulitple vlans with IP's and send them across one trunk as the trunk in HP world handles mulitple vlans.

I think we may be talking at cross purposes. If you turn on IP routing then the switch is no longer acting as a L2 switch. But you said in your original post the HP was acting as L2 not L3.

You are right when you say if you enable IP routing you can route for multiple vlans but then the switch would be acting as a L3 switch.

A trunk link carrying multiple vlans is a L2 concept not a L3 one.  So if your HP was meant to be acting as L2 you can have as many vlans as you need to at L2 and carry them across the trunk link. Same with Cisco switches.  But for traffic to route between the vlans you need either a router with subinterfaces or more likely a L3 switch with multiple L3 vlan interfaces.

I think maybe the confusion is coming because of the way i am referring to the L3 vlan interface. On a L2 switch you only have one L3 vlan interface ie. the interface with an IP address configured. This is used only so you can remotely connect to the switch to manage it. But you have two interfaces with IP addresses and this makes no sense on a L2 switch ie. a switch where IP routing is not enabled.

A L3 switch would have IP routing enabled and multiple L3 vlan interfaces each with an IP address. So you connect your HP switch via a trunk to the Cisco switch. For each user vlan you configure a L3 vlan interface on the Cisco switch with an IP address and use that as the default gateway for clients within that vlan.

The HP switch has as many vlans as you need at L2 but all L3 inter vlan routing is done by the Cisco switch.

From the sounds of it there is no difference between how HP do it and Cisco do.

If this is still not clear then just let me know which bit and i'll try and explain it in a different way.

Jon

8 REPLIES
Hall of Fame Super Blue

Re: HP Switch connected to Cisco Device Issue

Could you clarify what you can and cannot ping as i think there may be typos in your question.

So the Cisco switch is doing the inter vlan routing ?

Could you also perhaps not put x's in the 10.x.x.x addresses. These are private addresses so you are not disclosing any sensitive information and it would make it easier to read the configuration.

So the HP is connected via a trunk to the Cisco ?

What model is the Cisco switch ?

From the Cisco switch can you post -

1) "sh int trunk"

2) "sh vlan brief"

3) "sh ip int brief | include Vlan"

Jon

New Member

Re: HP Switch connected to Cisco Device Issue

Thanks for the reply Jon. Due to policy I have to use the X sorry.

I will try to clear up what I can ping.

On the HP device I can ping vlan 93's gateway which sit's on the Cisco, On the Cisco I can ping vlan 93's IP on the HP.

On the HP I cannot ping vlan 11's gateway on the Cisco device. On the Cisco I cannot ping vlan's 11's IP on the HP.

From outside of the building I cannot ping the HP's vlan 93's IP I can from withing the building SSH to it.

The HP is connected via Trunk to the Cisco

Cisco is a 3850

Yes, the Cisco should be doing the intervlan routing. I cannot post those at this time I will see if I can later.

Thanks

Hall of Fame Super Blue

Re: HP Switch connected to Cisco Device Issue

If HP switches work the same way as Cisco switches in terms of L2 vs L3 (and i suspect they do)  then you cannot have more than one L3 vlan interface on a L2 switch and this is only used to manage the switch not as a gateway for clients.

Only a L3 switch doing routing (or more precisely L3 switching) can have multiple L3 vlan interfaces.

In terms of being able to ping vlan 93 from outside the building that may be a separate issue but first you need to decide which vlan is used for management on the HP and Cisco switches.

Jon

New Member

Re: HP Switch connected to Cisco Device Issue

Thanks Jon,

The HP is just a layer 2 while the Cisco is layer 3. I will have to read up more on multiple vlans with HP's. Thanks again for your time.

Derek

Hall of Fame Super Blue

HP Switch connected to Cisco Device Issue

Derek

Just to clarify.

You can have multiple vlans at L2 and use a trunk from the HP, you just can't have multiple L3 vlan interfaces on a L2 switch, or at least you can't on a Cisco switch and i suspect the general rule applies.

Jon

New Member

Re: HP Switch connected to Cisco Device Issue

Jon,

I am new to the network world so maybe I'm missing something. On HP's if I have mulitlple vlans as long as I turn on IP routing and point them to a router or L3 switch I should be able to setup mulitple vlans with IP's and send them across one trunk as the trunk in HP world handles mulitple vlans. Before we introduced the Cisco it was going to another HP device and the other vlan's worked so maybe Cisco doesn't allow this for some reason but I cannot imagine that's the case. I'm sure I'm missing something stupid on the Cisco side just haven't figured it out yet.

Thanks,

Hall of Fame Super Blue

HP Switch connected to Cisco Device Issue

Derek

On HP's if I have mulitlple vlans as long as I turn on IP routing and point them to a router or L3 switch I should be able to setup mulitple vlans with IP's and send them across one trunk as the trunk in HP world handles mulitple vlans.

I think we may be talking at cross purposes. If you turn on IP routing then the switch is no longer acting as a L2 switch. But you said in your original post the HP was acting as L2 not L3.

You are right when you say if you enable IP routing you can route for multiple vlans but then the switch would be acting as a L3 switch.

A trunk link carrying multiple vlans is a L2 concept not a L3 one.  So if your HP was meant to be acting as L2 you can have as many vlans as you need to at L2 and carry them across the trunk link. Same with Cisco switches.  But for traffic to route between the vlans you need either a router with subinterfaces or more likely a L3 switch with multiple L3 vlan interfaces.

I think maybe the confusion is coming because of the way i am referring to the L3 vlan interface. On a L2 switch you only have one L3 vlan interface ie. the interface with an IP address configured. This is used only so you can remotely connect to the switch to manage it. But you have two interfaces with IP addresses and this makes no sense on a L2 switch ie. a switch where IP routing is not enabled.

A L3 switch would have IP routing enabled and multiple L3 vlan interfaces each with an IP address. So you connect your HP switch via a trunk to the Cisco switch. For each user vlan you configure a L3 vlan interface on the Cisco switch with an IP address and use that as the default gateway for clients within that vlan.

The HP switch has as many vlans as you need at L2 but all L3 inter vlan routing is done by the Cisco switch.

From the sounds of it there is no difference between how HP do it and Cisco do.

If this is still not clear then just let me know which bit and i'll try and explain it in a different way.

Jon

New Member

Re: HP Switch connected to Cisco Device Issue

Hi Jon,

Thanks for the reply, I haven't had a chance yet to respond but I think I was overthinking the issue since I was going from HP to Cisco now instead of HP to HP before.

Thanks,

Derek

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