Panasonic NN46240-710 - Manual (Page 151)

Nortel Secure Router 8000 Series
Troubleshooting - VPN___________ 4 MPLS L2VPN troubleshooting
You can use the undo mpls Layer 2 VPN default martini command to restore PWE3 mode.
If a VC has been configured, such a type of switching cannot be done.
Q: In what cases do I configure local-ce and local-mac in different media
interworking?
A: You must configure the local-ce and local-mac when you configure IP-interworking
encapsulation on an Layer 2 VPN Ethernet interface or subinterface on PE. After a Layer 2
VPN Ethernet interface is IP-interworking encapsulated, it learns MAC addresses in a new way.
Accordingly, its ARP entries are different from ordinary ARP entries.
When PE receives an ARP request from CE through an IP-interworking encapsulated Layer 2
VPN ingress interface, PE responds with its own MAC address regardless of the destination. At
this time, an Ethernet interface or subinterface of PE can connect only one CE, but cannot
connect multiple CEs through a hub or LAN switch. When an Ethernet interface or subinterface
of PE connects multiple CEs, PE can learn unhelpful MAC addresses, which can cause
forwarding failure.
Q: What special configuration should be done on an FR interface? What is the
configuration guideline when CE acts as DCE and PE functions as DTE?
A: When you configure FR, note that:
• You must configure a VC ID for a DCE or NNI interface regardless of whether it is a main
interface or a subinterface.
• For a DTE interface, if it is a main interface, the system automatically determines its VC
ID based on the remote device; if it is a subinterface, you must manually specify a VC ID
for it.
When CE adopts FR to access PE, there is no special requirement on the interface that connects
with CE on the PE.
In the two CEs setting up the connection, the interface that connects with PE on one CE is
specified as DCE while that of another CE is specified as DTE.
Refer to Figure 4-20.
Figure 4-20 Networking scheme using DCE and DTE as the interface types
ip
— — I
t Backbone^
DCE
CE1
PE2
DTE
CE2
If you configure LSP, configure link mapping to permit the broadcast packets if PEs are
connected through Non Broadcast Multiple Access (NBMA) network such as FR, ATM, and
X.25.
Issue 5.3 (30 March 2009) Nortel Networks Inc. 4-41