Cisco C881 Router setup/config & resources

midwestmetal · ‎01-29-2019

Hello all!

So, I recently began working for a company that's in a somewhat unusual situation. Their company is connected via a VPN to a partner company. On-site they a Cisco C881 router that provides the VPN connection, but also supplied PSTN necessary for their Cisco phones, which connect to a UC540 located at the location on the other end of the VPN tunnel. They also connect to a domain network via the VPN, which provides them with access to shared company files/folder via MS Active Directory (though the Windows user accounts are local accounts).

Here's my question. This week we're switching over to our own on-site server and domain network. But the phones, for now at least, still need to connect to the off-site UC540 via the VPN tunnel. I have no experience at all configuring the C881. I've only ever used/configured the RV-series, which uses a browser-based GUI. I just need to know how to do relatively basic things like setup a VLAN, configure static IPs for certain clients, etc., but I've had a really tough time finding resources that detail how to perform these functions via the command line interface on the C881. Could anyone help direct me to a resource for configuring VLAN and static IPs?

Georg Pauwen · ‎01-29-2019

Hello,

configuring the 881 is very easy actually, all you need is a console connection (see the link below).

Once you are connected, at the Router# prompt, type the following:

1. To add a VLAN with static IP address:

Router#conf t

Router(config)#vlan 10

Router(config)#int vlan 10

Router(config-if)#ip address 192.168.1.1 255.255.255.0

Anything else can be configured in a similar fashion...

https://www.cisco.com/c/en/us/td/docs/routers/access/800/hardware/installation/guide/800HIG/initalconfig.html#71434

midwestmetal · ‎01-31-2019

Thank you sir, I greatly appreciate it. In your post you wrote "vlan 10", is "10" the name of the VLAN I'd be creating?

Also, do you happen to know how I could create a backup of the router's settings prior to changing the configuration, just in case I make a mistake an need to revert to its current settings?

Georg Pauwen · ‎01-31-2019

Hello,

10 would be the VLAN number in this example, not the name. If you want to name your VLAN, just type:

Router#conf t

Router(config)#vlan 10

Router(config-vlan)#name VLAN10

Here, VLAN10 would be the name.

To backup your config, you would typically save the running config to a TFTP server using the 'cop run tftp' command. Check the document below for instructions:

Backup and Restore a Cisco Router with TFTP

https://www.petenetlive.com/KB/Article/0000538

midwestmetal · ‎01-31-2019

Thank you again sir, I greatly appreciate your assistance.

Last question for now. If I create a new VLAN, how do I add machines to that VLAN? Basically, we're creating a VLAN for our Active Directory domain controller and 5 machines that will connect to it. Everything else should stay on VLAN1 as those devices are our Cisco phones. The setup/administration guide I'm working from (here: https://www.cisco.com/en/US/docs/routers/access/800/880/software/configuration/guide/SCG_880_series.pdf) is helpful, but doesn't go into detail.

I basically new to create VLAN2, add 5 computers to it, and then set the ip address of one of those 5 computers to static DHCP so that it doesn't change. From what I've learned from you:

CREATE VLAN:

Router#conf t

Router(config)#vlan 2

Router(config-vlan)#name INTERNALAD

ADD CLIENTS:

Not sure

SET ONE MACHINE TO STATIC DHCP:

Router(config)# ip dhcp pool STATICVLAN2DC

Router(dhcp-config)# client-identifier unique-identifier

Router(dhcp-config)# hardware-address hardware-address type

Do you happen to know, when setting a machine to static DHCP IP, do I provide the MAC address? I'm working off of this to try to solve this and I'm just not 100% sure I understand what inputs to use for this step.

Georg Pauwen · ‎01-31-2019

Hello,

to add a client to a VLAN:

Router#conf t

Router(config)#interface FastEthernet1

Router(config-if)# switchport access vlan 10

Router(config-if)# spanning-tree portfast

Static DHCP:

ip dhcp pool STATICVLAN2DC
host 192.168.1.2 255.255.255.0
client-identifier 0100.4096.3944.3f

or

ip dhcp pool STATICVLAN2DC
host 192.168.1.2 255.255.255.0

hardware-address 0100.4096.3944

The difference is that hardware-address uses only the MAC address, while client-identifier uses the media type (01 is Ethernet, the first two digits).

midwestmetal · ‎01-31-2019

My goodness, you have taught me more than the last 10 days I've spent reading "CCNA Guide to Cisco Networking". Thank you so so so so much. Truly, I greatly appreciate it.

Could you possibly explain this to me a little bit?

Router#conf t

Router(config)#interface FastEthernet1

Router(config-if)# switchport access vlan 10

Router(config-if)# spanning-tree portfast

I'm just not sure where the client device is selected or what identifies it. Right now our Cisco C881 router is connected to a Cisco switch that has DHCP disabled, so the router handles all of that. If I'm moving a client from VLAN1 to VLAN2, I'll know the IP and MAC address of the devices I want to move, but where is that supplied? Or would I need to use a separate switch that's connected to a different port on the router? The switch we're using now is just in trunk mode for all ports, so there's no VLAN membership being applied on the switch.

Your description of how to set a static DHCP is excellent, thank you. I'll probably use the hardware identifier and I don't know how to determine the client identifier of a machine. So, using the hardware identifier, it'd look like this I believe.

ip dhcp pool STATICVLAN2DC
host 192.168.1.2 255.255.255.0

hardware-address 8y45.45a9.6dbc