Why isn't p2p1 bridged up in Ubuntu 14.04?

Question

Computer networks

Hello!
Installed Ubuntu Server 14.04 x64 on a Lenovo G500 laptop.
Network configuration after installation:

lo        Link encap:Локальная петля (Loopback)  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

p2p1      Link encap:Ethernet  HWaddr 20:89:84:f9:3a:e4  
          inet addr:192.168.1.100  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::2289:84ff:fef9:3ae4/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:16

Now I'm trying to raise the xenbr0 bridge for the p2p1 interface.
I do everything according to this instruction drybox.ru/?p=159
File /etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto p2p1
iface p2p1 inet manual

auto xenbr0
iface xenbr0 inet dhcp
bridge_ports p2p1
bridge_stp off
bridge_fd 0
bridge_maxwait 0

After a reboot, the bridge does not rise, i.e. there is no xenbr0 interface in ifconfig.
What could be wrong and how to fix it?

Answer 1

Looks like I'm not very careful.
Problem solved. it was necessary to install bridge-utils.