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How to configure PPP Multilink

Multilink is a way of bundling more than one PPP WAN links and bundle them together into one logical interface. This is one of the method you can implement when you have a primary and secondary links in place and create a logical conduit where both links are present.

This method can be used to load balance data across the links and at the same time it will support redundancy when one one link fails.

I have tested this configuration on 2 of my 2500 Routers and I haven’t tested these on more recent IOS so some commands may vary. I will be checking them on a pair of 3845s/2691s on a later date and will add my findings to this post.

As you can see the Diagram, I am using R4 and R5 which are connected via Serial 0 and Serial 1 respectivly.


R4 Configuration

Multilink Interface
interface Multilink1
ip address
ppp multilink
ppp multilink links maximum 2
ppp multilink links minimum 1
ppp multilink group 1

Serial 0

interface Serial0
no ip address
encapsulation ppp
clock rate 64000
ppp multilink
ppp multilink group 1

Serial 1

interface Serial1
no ip address
encapsulation ppp
clock rate 64000
ppp multilink
ppp multilink group 1

As you can see, since this is a lab scenario, I have set the clock rate on the link. If you are setting this up on a WAN link, you don’t need to do this as the circuit provider would be setting this up for you.

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How to Configure Frame-Relay

Frame-Relay is one of the core concept of networking and nowadays it is one of the under appreciated part on modern networking.

I am just going to go over how to configure it using 4 Routers and one will act as a Frame-Relay cloud.

Before I go ahead and explain the configuration, You can see the below diagram which represents the physical topology.


As you can see, FRS is connected via…

Serial 11 to R1 Serial 10
Serial 12 to R2 Serial 10
Serial 13 to R3 Serial 10

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IP helper-address Explained

All broadcasts messages are dropped by the router when it receives on an interface. This specific command is enables the router to convert the broadcast messages distended for a specific destination into unicast. This interface level command needs to be applied on the interface which the broadcast receives from. R1(config-if)#ip helper-address Also there are other options where you point the address to a vrf etc… The following broadcasts are forwarded by default… TIME – Port 37 TACACS – Port 49 DNS – Port 53 BOOTP/DHCP Server – Port 67 BOOTP/DHCP Client – Port 68 TFTP – Port 69 NetBIOS Name Service – Port 137 NetBios Datagram Service – Port 138 Other protocols can be forwarded by using the following Global config commanding… R1(config)#ip forward-protocol udp ? Use the ? to see the supported protocols. You may use the following command to remove a specific protocol being forwarded… R1(config)#no ip forward-protocol udp ? Read more

How to do an IOS Upgrade via TFTP

There are many free TFTP server sortware out there, just install one.

First of all, make sure you have IP reachablity to the TFTP Server. You can do that via Ping…

Then check whether TCP port 69 is open. Usually it is not the case, but when it comes to troubleshooting, it is the first thing to check after a succesful Ping test.

Jump onto the router you are going to do the IOS upgrade.

Make sure the IOS you are going to replace it with is compatible with your router & also you have the necessary Flash / RAM.

If your Flash is big enough to have more than two IOS images, then you can straight away go and download it from the TFTP Server.

If you are going to have two IOS images in flash, you need to specify the router which image to load on boot. It can be done via the following command…

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How to get Sky Broadband Login Info from the Router (Username & Password etc)

Sky Broadband is aimed for home users thus a few features like SSH (Port 22), VPN and other tunneling are disabled by the router (NETGEAR DG834GT) they provide. If you want to use these features, you have two choices… Use another Router Re-flash the firmware of the Sky Router (NETGEAR DG834GT) Re-flashing the router is risky and I am sure it is against Sky’s Terms and Conditions, because as far as I’m aware, that router is a property of Sky. If you are thinking of doing it, then Good Luck! Using another router is the smartest thing to do, But for you to use another router, you do need the Sky Username and Password. This is how you get the Sky Username and Password… Open up your browser and Copy and paste the following URL to the Address Bar. (Make sure its in one line, not two!) <br /> http://192. Read more

Virgin Media / Telewest Broadband Via Router (WRT54GS)

Since Telewest does not use authentication, it can be a bit puzzling if you are going to share your broadband internet connection via a Router. I will be using a LinkSys WRT54GS as an example… Before you do that, it is recommend doing the following… Turn off your modem and your Router for about 5 minutes so your PC MAC lease will expire so you can use your Router’s MAC If you are having MAC address issue, then you can get your Network Card’s MAC Address by going to Start = type CMD type ipconfig /all Write it down, login to the router and use the MAC Address Clone Feature. It’s a 12 Digit code, looks something like this 00-04-5B-89-21-7F If a cable provider does not use Authentication method, the only way to make your router talk to the modem is via Automatic Configuration – DHCP. Read more