How to add network interface to VM on Citrix Xen via console

Check interfaces:

[root@xenserver1 ~]# xe pif-list 
uuid ( RO)                  : cc9937fa-0435-7664-a73a-c9bfa803e50e
                device ( RO): eth3
    currently-attached ( RO): true
                  VLAN ( RO): -1
          network-uuid ( RO): e7a75876-ee65-950e-7975-6751eca3795b


uuid ( RO)                  : 3a5ef383-650a-ded9-d636-4c86a6831443
                device ( RO): eth1
    currently-attached ( RO): true
                  VLAN ( RO): -1
          network-uuid ( RO): bd91ea1e-6184-4f7b-6360-0134f39b9751


uuid ( RO)                  : 4c04ef06-9707-67ac-1859-6e6617d507a7
                device ( RO): eth2
    currently-attached ( RO): true
                  VLAN ( RO): -1
          network-uuid ( RO): 8d829397-e8d1-fdc2-b62d-8b23cf6da7dd


uuid ( RO)                  : 41b55f45-91ff-90e1-0a13-dbb680e744e9
                device ( RO): eth0
    currently-attached ( RO): true
                  VLAN ( RO): -1
          network-uuid ( RO): 78613a9f-aede-edc6-39f4-40c4c5883de2


uuid ( RO)                  : 72ff5545-3d4b-5038-aa15-dc93998b8dab
                device ( RO): eth0
    currently-attached ( RO): true
                  VLAN ( RO): 21
          network-uuid ( RO): 8310ea88-dad4-c989-19db-5c5fdb8d3edc

Create internal interface - not bounded to any physical interface :

[root@xenserver1 ~]# xe network-create name-label="anylan" name-description="anylan for testing"
919b5b1c-201f-fed2-c39d-21946f278bdc

Create tagged network interface bounded to physical NIC:

[root@xenserver1 ~]# xe network-create name-label="vlan402" name-description="VLAN 402" 
d5b6969c-eff4-79b2-0088-7740f8a9b492


[root@xenserver1 ~]# xe vlan-create network-uuid=d5b6969c-eff4-79b2-0088-7740f8a9b492 pif-uuid=41b55f45-91ff-90e1-0a13-dbb680e744e9  vlan=402
7dadd3ec-b8a2-5b40-0855-0ef365dc9f00

Example pif-list after adding new interface

[root@xenserver1 ~]# xe pif-list 
uuid ( RO)                  : 7dadd3ec-b8a2-5b40-0855-0ef365dc9f00
                device ( RO): eth0
    currently-attached ( RO): true
                  VLAN ( RO): 402
          network-uuid ( RO): d5b6969c-eff4-79b2-0088-7740f8a9b492


uuid ( RO)                  : cc9937fa-0435-7664-a73a-c9bfa803e50e
                device ( RO): eth3
    currently-attached ( RO): true
                  VLAN ( RO): -1
          network-uuid ( RO): e7a75876-ee65-950e-7975-6751eca3795b


uuid ( RO)                  : 3a5ef383-650a-ded9-d636-4c86a6831443
                device ( RO): eth1
    currently-attached ( RO): true
                  VLAN ( RO): -1
          network-uuid ( RO): bd91ea1e-6184-4f7b-6360-0134f39b9751


uuid ( RO)                  : 4c04ef06-9707-67ac-1859-6e6617d507a7
                device ( RO): eth2
    currently-attached ( RO): true
                  VLAN ( RO): -1
          network-uuid ( RO): 8d829397-e8d1-fdc2-b62d-8b23cf6da7dd


uuid ( RO)                  : 41b55f45-91ff-90e1-0a13-dbb680e744e9
                device ( RO): eth0
    currently-attached ( RO): true
                  VLAN ( RO): -1
          network-uuid ( RO): 78613a9f-aede-edc6-39f4-40c4c5883de2


uuid ( RO)                  : 72ff5545-3d4b-5038-aa15-dc93998b8dab
                device ( RO): eth0
    currently-attached ( RO): true
                  VLAN ( RO): 21
          network-uuid ( RO): 8310ea88-dad4-c989-19db-5c5fdb8d3edc

Check VM to attach new interface: we need to know number of devices and vm-uuid.

[root@xenserver1 ~]# xe vm-list 
uuid ( RO)           : 68ce65a4-01ec-4a23-9016-011aa20e59cf
     name-label ( RW): Control domain on host: xenserver1
    power-state ( RO): running


uuid ( RO)           : 66a6fcc2-b5b9-1eb9-cd26-c26d8df1e204
     name-label ( RW): Hadoop-master
    power-state ( RO): running


uuid ( RO)           : a79bc6f8-54d7-a562-ba14-4f50db2efc9b
     name-label ( RW): FreeBSD 9.2
    power-state ( RO): running


uuid ( RO)           : 8ac1c052-8448-6d9b-0a55-6e91e5be406c
     name-label ( RW): FreeBSD10
    power-state ( RO): halted


uuid ( RO)           : 03070e1e-2b04-5e4b-87f9-5db7d69131bb
     name-label ( RW): Hadoop-slave2
    power-state ( RO): running


uuid ( RO)           : d122b3bf-e914-83b0-5761-1430f205fa9c
     name-label ( RW): Hadoop-slave1
    power-state ( RO): running

[root@xenserver1 ~]# xe vif-list vm-name-label=FreeBSD\ 9.2
uuid ( RO)            : 49a107e2-0e81-a9dd-0595-218c07fe1af8
         vm-uuid ( RO): a79bc6f8-54d7-a562-ba14-4f50db2efc9b
          device ( RO): 2
    network-uuid ( RO): 56d7fd62-ba47-c12c-e371-bc7908739ad1


uuid ( RO)            : 03932dbf-d7e4-ed7d-d649-ac431a97d962
         vm-uuid ( RO): a79bc6f8-54d7-a562-ba14-4f50db2efc9b
          device ( RO): 1
    network-uuid ( RO): 8310ea88-dad4-c989-19db-5c5fdb8d3edc

Attach interface to VM:

[root@xenserver1 ~]# xe vif-create network-uuid=d5b6969c-eff4-79b2-0088-7740f8a9b492 vm-uuid=a79bc6f8-54d7-a562-ba14-4f50db2efc9b device=3 mac=random
758cf24a-2904-f3aa-8ed4-17d6ffebf032

[root@xenserver1 ~]# xe vif-create network-uuid=919b5b1c-201f-fed2-c39d-21946f278bdc  vm-uuid=a79bc6f8-54d7-a562-ba14-4f50db2efc9b  device=4 mac=random
3504d19f-2413-e066-6d30-1878adfbd117

Result:

[root@xenserver1 ~]# xe vif-list vm-name-label=FreeBSD\ 9.2
uuid ( RO)            : 49a107e2-0e81-a9dd-0595-218c07fe1af8
         vm-uuid ( RO): a79bc6f8-54d7-a562-ba14-4f50db2efc9b
          device ( RO): 2
    network-uuid ( RO): 56d7fd62-ba47-c12c-e371-bc7908739ad1


uuid ( RO)            : 758cf24a-2904-f3aa-8ed4-17d6ffebf032
         vm-uuid ( RO): a79bc6f8-54d7-a562-ba14-4f50db2efc9b
          device ( RO): 3
    network-uuid ( RO): d5b6969c-eff4-79b2-0088-7740f8a9b492


uuid ( RO)            : 03932dbf-d7e4-ed7d-d649-ac431a97d962
         vm-uuid ( RO): a79bc6f8-54d7-a562-ba14-4f50db2efc9b
          device ( RO): 1
    network-uuid ( RO): 8310ea88-dad4-c989-19db-5c5fdb8d3edc


uuid ( RO)            : 3504d19f-2413-e066-6d30-1878adfbd117
         vm-uuid ( RO): a79bc6f8-54d7-a562-ba14-4f50db2efc9b
          device ( RO): 4
    network-uuid ( RO): 919b5b1c-201f-fed2-c39d-21946f278bdc

Depends of configuration probably you'll need to shutdown your machine and start it again thus system could determine network interface.