VLANS -- IP Route and Mismatched IP Class ?

[ZACiscoKid]

Hi All ,

Hope you can help out with this question -- could be convoluted

Purchased Mr Lammles book and working towards CCNA

I am using an 877 as a test bed and for access to the Internet

Currently working through VLANS on the 877 -- learning by doing and referring back to the book.

I am currently stumped by what this ip route is showing me

-----------
Gateway of last resort is x.x.x.x [ ISP Gateway] to network 0.0.0.0

172.20.0.0/24 is subnetted, 1 subnets
C 172.20.16.0 is directly connected, Vlan3
C 192.168.20.0/24 is directly connected, Vlan6
x.x.x.x/32 is subnetted, 2 subnetsx
C x.x.x.x is directly connected, Dialer0
C x.x.x.x is directly connected, Dialer0
S* 0.0.0.0/0 [1/0] via x.x.x.x
--------------------

I have two VLAN's setup and a Dialer to the Internet. Everything appears to be working but I am stumped by what is shown for the one VLAN

172.20.0.0/24

THis appears to be a Class B address ?
As far as I know all my IP's and masks are correct and I have NO Class B settings on that VLAN

The other VLAN 192.168.20.0 is pretty much a clone of the other one and is NOT showing any subnets ?

Why is the 172 VLAN subnetted ?

Should it be like this ?

IF not what is it indicative of -- and how would I correct it ?

Can supply more info if needed

Many thanks

[ZACiscoKid]

Originally Posted by ZACiscoKid

Hi All ,

Hope you can help out with this question -- could be convoluted

Purchased Mr Lammles book and working towards CCNA

I am using an 877 as a test bed and for access to the Internet

Currently working through VLANS on the 877 -- learning by doing and referring back to the book.

I am currently stumped by what this ip route is showing me

-----------
Gateway of last resort is x.x.x.x [ ISP Gateway] to network 0.0.0.0

172.20.0.0/24 is subnetted, 1 subnets
C 172.20.16.0 is directly connected, Vlan3
C 192.168.20.0/24 is directly connected, Vlan6
x.x.x.x/32 is subnetted, 2 subnetsx
C x.x.x.x is directly connected, Dialer0
C x.x.x.x is directly connected, Dialer0
S* 0.0.0.0/0 [1/0] via x.x.x.x
--------------------

Well the only thing convoluted is the Brain Process

* 172 range is by DEFAULT Class B * -- DUH

( SORRY Mr Lammle )


OK -- someone suggested "ip classless" but this is not gong to change what Cisco is doing with the Class B subnet within the VLAN

CK

[HermeszData]

Originally Posted by ZACiscoKid

Hi All ,

Hope you can help out with this question -- could be convoluted

Purchased Mr Lammles book and working towards CCNA

I am using an 877 as a test bed and for access to the Internet

Currently working through VLANS on the 877 -- learning by doing and referring back to the book.

I am currently stumped by what this ip route is showing me

-----------
Gateway of last resort is x.x.x.x [ ISP Gateway] to network 0.0.0.0

172.20.0.0/24 is subnetted, 1 subnets
C 172.20.16.0 is directly connected, Vlan3
C 192.168.20.0/24 is directly connected, Vlan6
x.x.x.x/32 is subnetted, 2 subnetsx
C x.x.x.x is directly connected, Dialer0
C x.x.x.x is directly connected, Dialer0
S* 0.0.0.0/0 [1/0] via x.x.x.x
--------------------

I have two VLAN's setup and a Dialer to the Internet. Everything appears to be working but I am stumped by what is shown for the one VLAN

172.20.0.0/24

THis appears to be a Class B address ?
As far as I know all my IP's and masks are correct and I have NO Class B settings on that VLAN

The other VLAN 192.168.20.0 is pretty much a clone of the other one and is NOT showing any subnets ?

Why is the 172 VLAN subnetted ?

Should it be like this ?

IF not what is it indicative of -- and how would I correct it ?

Can supply more info if needed

Many thanks

First, remember that VLANs are not subnetted. You normally assign LAN subnets to VLANs for several reasons as Todd tries to beat into our heads in his book.

Second, VLANs are not normally assigned to WAN connections as you have done here. To my knowledge, there are no VWANs.

Wht the output is telling you is that the IP address assigned you by your ISP is Sub-netted. I would go back and review routing protocols to better understand this.

SO, the sh ip route output you are concerned about does not have anything to do with VLANs except that you have mistakenly assigned a VLAN ID to your WAN Connection.

Below is a similar output from my BackBone Router. The information below does not list my actual IP address. It does list the gateway and how it fits into the the ISPs block of addresses. This is one way we can learn a little about the overall network layout, both local area and wide area.

Gateway of last resort is 174.51.240.1 to network 0.0.0.0
68.0.0.0/32 is subnetted, 1 subnets
S 68.87.66.13 [254/0] via 174.51.240.1, FastEthernet0/0
174.51.0.0/20 is subnetted, 1 subnets
C 174.51.240.0 is directly connected, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 9 subnets, 2 masks
O 10.10.1.1/32 [110/2] via 10.10.11.254, 1d06h, FastEthernet0/1 (this is the loopback address of my terminal server)
C 10.10.11.0/27 is directly connected, FastEthernet0/1.101
C 10.10.11.32/27 is directly connected, FastEthernet0/1.102
C 10.10.11.64/27 is directly connected, FastEthernet0/1.103
C 10.10.11.96/27 is directly connected, FastEthernet0/1.104
C 10.10.11.128/27 is directly connected, FastEthernet0/1.105
C 10.10.11.160/27 is directly connected, FastEthernet0/1.106
C 10.10.11.192/27 is directly connected, FastEthernet0/1.107
C 10.10.11.224/27 is directly connected, FastEthernet0/1
S* 0.0.0.0/0 [254/0] via 174.51.240.1

I hope this helps a bit!

And to the previous poster, there is no need to be condescending! The original question is actually very valid.

[HermeszData]

I just went back to review the original post and realized a couple of things. So, instead of modifying my post above, I decided to amend my precious post here.

The 877 routers work a little differently than the Classic Cisco routers in that the FastEthernet ports are actually a built in switch. For this reason, you had to assign IP address via VLANs.

Any time you have routing set up and the routed networks properly configured, the SH IP ROUTE command will show all the possible routes.

In your case, you had one VLAN set up with an IP address in the 172.20.0.0/24 network. Because this is a classful network is appears in your routing table as a directly connected network via the VLAN you assigned the IP Address to.

What caused my confusion in the previous post what your removial of certain IP information in the interest of security. That really was not necessary (but still understandable) because unless you have a Static Public IP address and you use that IP address as your "Exit Interface" your ip address never shows up.

it displays just as your snippit did:

*.*.*.* via Dialer0

Hope that clears things a bit more.

John