3 mtu, 2 vpls troubleshooting, 1 typical networking – Panasonic NN46240-710 User Manual
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5 VPLS troubleshooting
Nortel Secure Router 8000 Series
_________ Troubleshooting - VPN
5.1.3 MTU
In VPLS, the maximum transmission unit (MTU) refers to the maximum transmission unit of
the link layer. The encapsulation type and the MTU are both regarded as the Layer 2
information and are processed.
The MTU of respective VPLS must be consistent in a same VPN. If inconsistency occurs, the
PW cannot be set up successfully.
5.2 VPLS troubleshooting
This section covers the following topics:
•
•
•
5.2.1 Typical networking
Basic topology
Figure 5-1 Basic VPLS networking
Loopbacki
1.1.1.9/32
PE1
Ethernet1/0/0
POS2/0/0
^^168.1.1.1/24
Loopback1
2.2.2.9/32
CE1
POS1/0/0
168.1.1.2/24
____ POS2/0/0
^^,169.1.1.1/24
POS1/0/0
169.1.1.2/24
Loopback1
3.3.3.9/32
PE2
Ethernet2/0/0
CE2
Figure 5-1 shows a basic VPLS topology and adopts the following solutions:
•
CE1 and CE2 belong to the same VPN.
•
The Interior BGP (IBGP) neighbor is set up between PE1 and PE2 to transmit VPN
routing information carrying the inner label
The PE1 and PE2 are user access devices on the public network, functioning like a Layer 2
device. For a packet sent from CE1, two layers (inner and outer) of MPLS labels are added
before being forwarded. The packet is forwarded on the public network by using the outer label
(that is, public network tunnel label). The corresponding VSI is found according to the inner
label (that is, PW label) and the Layer 2 forwarding is performed and the packet is forwarded to
CE2.
5-4
Nortel Networks Inc.
Issue 5.3 (30 March2009)
P