---
title: SetTxPacketTailroom
framework: networkingdriverkit
role: symbol
role_heading: Instance Method
path: networkingdriverkit/iousernetworkethernet/settxpackettailroom
---

# SetTxPacketTailroom

Reserves the specified number of bytes at the end of each packet.

## Declaration

```occ
kern_return_t SetTxPacketTailroom(uint16_t numBytes);
```

## Parameters

- `numBytes`: The number of bytes to reserve at the end of the packet buffer.

## Return Value

Return Value kIOReturnSuccess on success, or another value if an error occurred.

## See Also

### Configuring Link Attributes

- [SetTxPacketHeadroom](networkingdriverkit/iousernetworkethernet/settxpacketheadroom.md)
- [SetSoftwareVlanSupport](networkingdriverkit/iousernetworkethernet/setsoftwarevlansupport.md)
- [SetMulticastAddresses](networkingdriverkit/iousernetworkethernet/setmulticastaddresses-7wjbn.md)
- [SetAllMulticastModeEnable](networkingdriverkit/iousernetworkethernet/setallmulticastmodeenable-5rtva.md)
- [SetPromiscuousModeEnable](networkingdriverkit/iousernetworkethernet/setpromiscuousmodeenable-82bt.md)
- [SetWakeOnMagicPacketSupport](networkingdriverkit/iousernetworkethernet/setwakeonmagicpacketsupport.md)
- [SetWakeOnMagicPacketEnable](networkingdriverkit/iousernetworkethernet/setwakeonmagicpacketenable.md)
- [IOUserNetworkMACAddress](networkingdriverkit/iousernetworkmacaddress.md)