Figure 78: Inter-As Topology With End-To-End Stacked Mpls Tunnels - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - BGP AND MPLS CONFIGURATION GUIDE 2010-10-12 Configuration Manual
Software for e series broadband services routers bgp and mpls configuration guide
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Figure 78: Inter-AS Topology with End-to-End Stacked MPLS Tunnels
Example
Copyright © 2010, Juniper Networks, Inc.
PE 1 assigns labels for routes to the customer sites, and distributes both the label
assignments and the VPN-IPv4 routes throughout AS 42 in extended BGP update
messages by means of internal MP-BGP. ASBR 2 then distributes the routes to ASBR 3
with external MP-BGP; ASBR 2 specifies itself as the next-hop address and assigns a
new label to the route so that ASBR 3 can properly direct traffic. ASBR 3 propagates the
routes by internal MP-BGP throughout AS 35, including to PE 4.
You can use the show ip bgp vpn all field in-label and show ip bgp vpn all field out-label
commands in the context of each VPN element to display the in label and out label
associated with the route at that point. Suppose that CE 1 advertises a route to prefix
10.10.10.11/32 to its external BGP peer PE 1 (10.2.2.2) in VRF A. PE 1 associates the label
16 with this route; an extended update message sent to internal MP-BGP peer ASBR 2
carries this information as a labeled VPN-IPv4 prefix (label 16, RD 100:0, IPv4 prefix
10.10.10.11/32).
host1:pe1#show ip bgp vpn all field in-label
Prefix
In-label
10.10.10.11/32
16
On PE 1, no out label is associated with the IPv4 prefix 10.10.10.11/32.
host1:pe1#show ip bgp vpn all field out-label
Prefix
Out-label
10.10.10.11/32
none
ASBR 2 receives the labeled VPN-IPv4 prefix and generates a new label, 44, to associate
with this VPN-IPv4 prefix instead of label 16 when it sends the prefix to ASBR 3.
host1:asbr2#show ip bgp vpn all field out-label
Prefix
Out-label
10.10.10.11/32
16
host1:asbr2#show ip bgp vpn all field in-label
Prefix
In-label
10.10.10.11/32
44
ASBR 2 receives MPLS frames with label 44 (the in label) from ASBR 3 and sends MPLS
frames with label 16 (the out label) to PE 1.
Chapter 6: Configuring BGP-MPLS Applications
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Troubleshooting
