Introduction

What is TTL?

Time to live (TTL) refers to the amount of time or “hops” that a packet is set to exist inside a network before being discarded by a router.

Background

Our current setup has us configure our client routers such that the default TTL for any traffic leaving the router is set to one.

This means that customers behind our routers cannot be able to use a routing device as all traffic would be dropped at our demarcation point. The only way this would work is if we use a switching/bridging device that does not add to the hops of the client traffic.

Recommended devices that would not need us to change the firewall rules include access points, switches and hubs with the former 2 being most commonly available in the market. These device models that customers may require to extend home-wifi range include:

1. TP-Link Access Points: The model range starts with TL-WAXXXX where the last 4 X digits represent the specific device model.

2. D-Link Access Points: The model range starts with DAP-XXXX or DMG-XXXX where the last 4 X digits represent the specific device model.

3. Tenda Access Points: The model range starts with APX where the last X digit represents the specific device model.

Important to note:

• The customer will have to buy the device at their own expense
• poa! will not come for any support visit services for this
• poa! will not support the device in any way (we will only check up to the demarcation point (hAP Lite)

Configuration Management

In some scenarios like as seen in the customer ticket 453557 we may need to change the TTL to allow for such setups to work.

In order to change the TTL, we need to log in to the client router and access the /ip/firewall/mangle settings as seen in the image below:

Click on the rule with TTL then scroll down to the bottom of the page that opens so you can see the TTL value settings as seen below:

As seen the firewall rule explicitly changes the TTL value of any packet traversing to 1 which causes the packets to be dropped on the next hop when TTL goes to 0.

The world of the internet has become ‘smaller’ and we do not need to use the maximum TTL value of 255. The standard traceroute does 30 hops maximum by default which means setting a TTL of 60 will help customers behind the router to work with any routing device. However, we will not be liable for how the client extra router/device is configured.

The final TTL should be as below: