ā06-15-2011 08:32 AM - edited ā03-07-2019 12:49 AM
Hi,
i know the native vlan by default is vlan1
but what does this command do switchpoirt trunk native vlan 5
int fas0/5
swtichport mode trunk
switport trunk native vlan 5
does this mean anything connected to this port will get ip address in vlan 5 ? and what does switchport trunk native vlan 5 mean >
Thanks
ā06-15-2011 08:34 AM
It defines the traffic that will be untagged across the trunk. It must match on both ends of the trunk for the trunk to come up.
ā06-15-2011 08:50 AM
i have applied this config to nortel ip phones
int fa0/5
switchport mode trunk
switchport trunk native vla 5
switchport trunk encap dot1q
the ip phones seems to get an ip address
but it doesnt seem to get ann ip address on
switcport mode trunk
switch trunk native vla1
switch trunk encap dot1q
Thanks
ā06-15-2011 08:52 AM
Sorry error in config. this is the correct one
i have applied this config to nortel ip phones
int fa0/5
switchport mode trunk
switchport trunk native vla 5
switchport trunk encap dot1q
switchport voice vlan105
the ip phones seems to get an ip address in 105 range
but it doesnt seem to get ann ip address on
switcport mode trunk
switch trunk native vla1
switch trunk encap dot1q
switchport voice vlan105
Thanks
ā06-15-2011 09:15 AM
Do you have an ip address range configured to interface Vlan1? If not, that is why you don't get an ip address.
ā06-15-2011 09:19 AM
yes i have a vlan 1 and the same switch is acting as a dhcp server as well in the same range
ā06-15-2011 10:13 AM
Is there any reason in particular that you are using a voice vlan to a nortel phone? Typically, your config would look like
int fa0/5
switchport mode trunk
switchport trunk native vla 5
switchport trunk encap dot1q
spanning-tree portfast trunk
wihout the
switchport voice vlan105
ā06-16-2011 12:00 AM
yes we have daisy chained the pc to phones...so we want pc on native vlan and phones on vla 105
ā06-16-2011 12:11 AM
Hi,
switchport voice vlan is used usually on access port making it a 'mini-trunk' carrying only tagged frames from the IP phone and untagged frames from PC attached and it uses CDP to advertise the phone which VLAN it must be tagging its frames with.
It should be working only with Cisco phones, if you configured VLAN on your phones then this command here has no effect as you are already using a trunk port which by default transports all frames( tagged and untagged).
Regards.
Alain.
ā06-16-2011 12:30 AM
hi,
we are using nortel phones on cisco switches..nortel phones dont use cdp hence the above config.
int fa0/1
switchport mode trunk
switcpot trunk native vlan 5
switchport voice vlan 105
the above native forces pc (untagged frames) to go through trunk and phones go through as well but as soon as they reach vlan 5 i have otpion 128 and option 191 which forces to go through vlan105 (voice dhcp) and gets an address. this works fine but it just does work on the vlan 1..dont know why?
int fas0/1
switchport mode trunk
switchport native vlan1
switchport voice vla105
any clues?
int vl 1
ip addres 172.22.1.1 255.255.255.0
int vl5
ip address 172.22.5.1 255.255.255.0
int 105
ip address 172.22.105.1 255.255.255.0
ip dhcp pool vlan1
network 172.22.1.0 255.255.255.0
domain name...
dns server...
ip dhcp pool vlan5
network 172.22.5.0 255.255.255.0
domain name...
dns server...
ip dhcp pool vlan105
network 172.22.105.0 255.255.255.0
domain name...
dns server...
also i have one more doubt ? switchport native vlan 5 means all untaged frames will go as vlan 5 on the trunk - does this get tagged ? (bcos native vlan does not tag packets) - if it doesnt tag 5 then how does it get an ip address ?
ā06-16-2011 01:59 AM
What is the relationship between a VID tag and an IP address? these are 2 unrelated concepts.
You have 2 DHCP scopes on your router/L3 switch so you need a IP helper -address because the DHCP discovers are broadcasted and so not propagated outside your broadcast domain. So the DHCP server knows which scope it must pick an IP from to offer you.
Could you clarify your question and maybe put a diagram along with what is working and not working.
Regards.
Alain.
ā06-17-2011 02:01 PM
hi,
ok the l3 switch has multple vlans and dhcp scope for each vlan all on the same layer 3 switch. multiple svi are used on this l3 switch for each vlan. we have layer 2 switches connected to it as access switches. so do i need an ip-helper address for each vlan even if it dhcp is running locally on the switch ( i thought ip helper is needed only dhcp service is running elsewhere)
this is first doubt to start with ?
Thanks
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