Vlan on subinterface problem

[krybabie]

hi

i was trying to subinterface a ether0 interface on a 2621 router.

I could only add a IP with dot1q encapsulation enabled.

Now the ether is plugged into a switch and the two ip's i can ping on the router. The eth0 int works fine but the subinterface will not speak to the connection on the other side.

Hope you can help

Thanks

Malcolm

[Kevin Dorrell]

Does the 2621 support 802.1Q runking on an Ethernet interface with the software version you have? Probably not. Which version of IOS is it? If you are lucky, some versions support 802.1Q on 10BaseT, but usually not officially.

Kevin Dorrell

Luxembourg

[krybabie]

hi

version 12.3 (6)a

filename of IOS

c2600-spservicesk9-mz.123-6a.bin

thanks

malcolm

[Kevin Dorrell]

OK, if it is an SP image, then it should support it. I'm still not clear what you are trying to achieve with a subinterface and no 802.1Q. Could you explain a bit more please. Thanks in advance.

Kevin Dorrell

Luxembourg

[krybabie]

i am trying to get two ip's on one physical interface.

Thats why i subinterfaced it but you can't put an ip on a subinterface without dot1q encap.

thats the basic problem

then i will use eigrp to route - but thats later.

[MUHAMMAD SHAHEEN]

If you want from int config prompt you can configure second/third/fouth IP range by using secondry word at the end and there is no need to go into dot1q/subinterface level. See this example below. You will need IP routing enabled on the global config to get this working.

interface Fa 0/0

description Loacl LAN

ip address 10.10.102.2 255.255.255.0 secondary

ip address 10.10.103.2 255.255.255.0 secondary

ip address 10.10.101.2 255.255.255.0

Good Luck

Shaheen

[MUHAMMAD SHAHEEN]

If you want from int config prompt you can configure second/third/fouth IP range by using secondry word at the end and there is no need to go into dot1q/subinterface level. See this example below. You will need IP routing enabled on the global config to get this working.

interface Fa 0/0

description Loacl LAN

ip address 10.10.102.2 255.255.255.0 secondary

ip address 10.10.103.2 255.255.255.0 secondary

ip address 10.10.101.2 255.255.255.0

Good Luck

Shaheen

[Kevin Dorrell]

That's right, if you don't want to use 802.1Q to distinguish the subnets, you can put them all on the physical interface as secondaries, and forget all about subinterfaces.

BUT ... just a word of warning ... when you come to configure EIGRP, EIGRP can happily advertise the secondary address ranges. But it will only form adjacencies with other routers across the primary address. That is, if you have another router on the same physical network and in the primary address range, then the routers will pick up routes from each other. If the other router is in one of the secondary address ranges, then they won't.

Hope this helps.

Kevin Dorrell

Luxembourg

[paddyxdoyle]

Malcolm i don't quite understand what you mean.

When you say the subinterface will not speak to the connection on the otherside, are you refering to a switch port or a router interface

Have you allocated your dot1q interface on your router to a specific VLAN?

Is the port on the otherside in this VLAN?

You mention that you can only add an IP with dot1q encapsulation, is this not what your are trying to achieve, are your looking to use secondary ip addressing on your interface instead of dot1q truking?

Rgds

PD