<p>As can be <a href="https://github.com/lightningnetwork/lightning-rfc/blob/master/11-payment-encoding.md" rel="nofollow noreferrer">read in BOLT 11</a> of the lightning protocol spec </p>

<blockquote>
  <p>the f field allows on-chain fallback; however, this may not make sense for tiny or time-sensitive payments</p>
</blockquote>

<p>it is one of the fields encoded into a BOLT 11 invoice</p>

<blockquote>
  <p>f (9): data_length variable, depending on version. Fallback on-chain address: for Bitcoin, this starts with a 5-bit version and contains a witness program or P2PKH or P2SH address.</p>
</blockquote>

<p>In case a payment can't be routed it is possible to pay this invoice with an onchain bitcoin transaction instead of opening a new channel. This obviously can't be done for sub dust payments and even for tiny payments above the dust limit this might not be economically viable. </p>

CC BY-SA 4.0
2019-07-30T19:42:03.090Z
Is there any option to add such fallback using c-lightning when creating an invoice?
baysx
CC BY-SA 4.0
2019-07-30T20:58:18.353Z
Yes check `lightning-cli help invoice` to be able to read the manage (:
Rene Pickhardt
CC BY-SA 4.0
2019-07-30T19:19:22.450Z
2019-07-30T19:19:22.450Z
Rene Pickhardt
<p>Just saw a "fallback" property in LN invoice. Never seen before. Can you please describe what that means and how I can make an invoice with same property?</p>

<p>I am using c-lightning. This is what i had decoding invoice:</p>

<pre><code>{
   "currency" : "bc",
   "created_at" : 1564513459,
   "expiry" : 3600,
   "payee" : "03efccf2c383d7bf340da9a3f02e2c23104a0e4fe8ac1a880c8e2dc92fbdacd9df",
   "msatoshi" : 1000000000,
   "amount_msat" : "1000000000msat",
   "description" : "satoshis-tennis-1564513459.3110697",
   "min_final_cltv_expiry" : 10,
   "fallbacks" : [
      {
         "type" : "P2SH",
         "addr" : "3MXqbMwf457U4Jaw35WnJdnL99mq7Q8oQQ",
         "hex" : "a914d9a625fb64a9faa4600548ae97e8efda9294dd0a87"
      }
   ],
   "routes" : [
      [
         {
            "pubkey" : "0276e09a267592e7451a939c932cf685f0754de382a3ca85d2fb3a864d4c365ad5",
            "short_channel_id" : "557233x2338x0",
            "fee_base_msat" : 1000,
            "fee_proportional_millionths" : 9,
            "cltv_expiry_delta" : 14
         }
      ]
   ],
   "payment_hash" : "de210472f7e9513358a22db99ee5b987e9fe96d523d0d833fd900837aa71199a",
   "signature" : "3045022100c79fc20087480d302a68c3b92b34de935956202c0499cf8acc182837c871923202200879fd3979aa688a46703c31f7e56ea5e7917f4820da42177d31fc2a9290c91a"
}
</code></pre>

<p>I am in particular interested in the following part:</p>

<pre><code>
    "fallbacks" : [ { "type" : "P2SH", "addr" : "3MXqbMwf457U4Jaw35WnJdnL99mq7Q8oQQ", "hex" : "a914d9a625fb64a9faa4600548ae97e8efda9294dd0a87" } ],
</code></pre>

<lightning-network>
What means "fallbacks" in LN invoices?
baysx
# What means "fallbacks" in LN invoices?

(Asked by: username_0 on 2019-07-30)

Just saw a "fallback" property in LN invoice. Never seen before. Can you please describe what that means and how I can make an invoice with same property?

I am using c-lightning. This is what i had decoding invoice:

```
{
   "currency" : "bc",
   "created_at" : 1564513459,
   "expiry" : 3600,
   "payee" : "03efccf2c383d7bf340da9a3f02e2c23104a0e4fe8ac1a880c8e2dc92fbdacd9df",
   "msatoshi" : 1000000000,
   "amount_msat" : "1000000000msat",
   "description" : "satoshis-tennis-1564513459.3110697",
   "min_final_cltv_expiry" : 10,
   "fallbacks" : [
      {
         "type" : "P2SH",
         "addr" : "3MXqbMwf457U4Jaw35WnJdnL99mq7Q8oQQ",
         "hex" : "a914d9a625fb64a9faa4600548ae97e8efda9294dd0a87"
      }
   ],
   "routes" : [
      [
         {
            "pubkey" : "0276e09a267592e7451a939c932cf685f0754de382a3ca85d2fb3a864d4c365ad5",
            "short_channel_id" : "557233x2338x0",
            "fee_base_msat" : 1000,
            "fee_proportional_millionths" : 9,
            "cltv_expiry_delta" : 14
         }
      ]
   ],
   "payment_hash" : "de210472f7e9513358a22db99ee5b987e9fe96d523d0d833fd900837aa71199a",
   "signature" : "3045022100c79fc20087480d302a68c3b92b34de935956202c0499cf8acc182837c871923202200879fd3979aa688a46703c31f7e56ea5e7917f4820da42177d31fc2a9290c91a"
}

```

I am in particular interested in the following part:

```

    "fallbacks" : [ { "type" : "P2SH", "addr" : "3MXqbMwf457U4Jaw35WnJdnL99mq7Q8oQQ", "hex" : "a914d9a625fb64a9faa4600548ae97e8efda9294dd0a87" } ],

```

**Tags:** lightning-network


---

## 1 answers

### Answer by username_1 on 2019-07-30. Score: 2 | Accepted answer

As can be [read in BOLT 11](https://github.com/lightningnetwork/lightning-rfc/blob/master/11-payment-encoding.md) of the lightning protocol spec

> the f field allows on-chain fallback; however, this may not make sense for tiny or time-sensitive payments

it is one of the fields encoded into a BOLT 11 invoice

> f (9): data\_length variable, depending on version. Fallback on-chain address: for Bitcoin, this starts with a 5-bit version and contains a witness program or P2PKH or P2SH address.

In case a payment can't be routed it is possible to pay this invoice with an onchain bitcoin transaction instead of opening a new channel. This obviously can't be done for sub dust payments and even for tiny payments above the dust limit this might not be economically viable.

> **Comments:**
> **username_0**: Is there any option to add such fallback using c-lightning when creating an invoice?  
> **username_1**: Yes check `lightning-cli help invoice` to be able to read the manage (:  

---

