Forward data traffic, 2 mpls l3vpn troubleshooting, 1 typical networking – Panasonic NN46240-710 User Manual
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Nortel Secure Router 8000 Series
Troubleshooting - VPN___________
3 BGP/MPLS IP VPN troubleshooting
routers. The LSPs can implement a variety of Quality of Service (QoS) functions through
configuration.
Forward data traffic
Use Figure 3-2 as an example. If Site 2 has the host (10.2.3.4/16), CE2 performs the
longest-match on the destination IP address and forwards packets to PE2.
The MPLS uses two layers of labels to forward packets from PE2 to PE1.
For this data stream, PE2 is the ingress LSR of the LSP, and PE1 is the egress LSR of the LSP.
The PE2 pushes a label (109569, for example) into the label stack, which serves as the inner
label before transmission of packets.
PE1 distributes routing information to the 10.1.0.0/16 segment by using IBGP. When PE2
receives the routing information, label 109569 is allocated to VRF1.
The PE2 pushes the original MPLS label from the next hop (the P router) to the label stack,
which will make it act as the outer label.
After the label enters the stack and once PE2 receives packets, PE2 searches for routes in VRF1.
The following information can be obtained:
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Private network label distributed by PE1 (with the label value being 109569)
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BGP next hop of the route (loopback address of PE1)
•
Egress interface (or subinterface) of the LSP from PE2 to PE1
•
Original MPLS label from PE2 to PE1
Along the LSP, PE2 forwards MPLS packets from the egress interface to the first P. The P router
exchanges packets based on the outer label. The penultimate P pops the outer label and
forwards packets to the PE1.
After receiving packets, based on the inner label 109596, the PE1 identifies the next hop to the
10.1/16 segment is the directly connected CE1. The PE1 forwards IPv4 packets to CE1. The
CE1 then forwards them to the server 10.1.3.8/16 of Site 1.
3.2 MPLS L3VPN troubleshooting
This section covers the following topics:
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•
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3.2.1 Typical networking
Figure 3-3 shows a typical MPLS L3VPN networking. Consider this networking to discuss
MPLS L3VPN troubleshooting as follows:
Issue 5.3 (30 March 2009)
Nortel Networks Inc.
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