3com 3031 Instruccion De Instalación
694
C
HAPTER
54: BGP/MPLS VPN C
ONFIGURATION
Figure 167 Route filtering via matching VPN target attribute
The routes for other VPNs will not appear in the routing table of the VPN in
question using VPN Target attribute to filter routing information received at PE
router, so the CE-transmitted data will only be forwarded within the VPN.
question using VPN Target attribute to filter routing information received at PE
router, so the CE-transmitted data will only be forwarded within the VPN.
BGP/MPLS VPN
Implementation
BGP/MPLS VPN works on this principle: It uses BGP to propagate VPN private
routing information on carrier backbone network and MPLS to forward VPN
service traffic.
routing information on carrier backbone network and MPLS to forward VPN
service traffic.
Advertising VPN routing information via BGP
1 Routing information exchange between CE and PE
A PE router can learn routing information about the CE connected to it through
static route, RIP (supporting multi-instance), OSPF (supporting multi-instance) or
EBGP, and imports it in a vpn-instance.
static route, RIP (supporting multi-instance), OSPF (supporting multi-instance) or
EBGP, and imports it in a vpn-instance.
2 Routing information exchange between ingress PE and egress PE
The ingress PE router uses MP-BGP to advertise routing information learned from
CE to the egress PE router (with MPLS label) and learn the CE routing information
learned at the egress PE router. You can use LDP to establish best-effort
forwarding LSPs or use RSVP (Resource Reservation Protocol) to establish specific
QoS-supported LSPs or traffic engineering-based LSPs. This chapter only discusses
the LSPs established with LDP, which will form full-connected LSP between PE
routers.
CE to the egress PE router (with MPLS label) and learn the CE routing information
learned at the egress PE router. You can use LDP to establish best-effort
forwarding LSPs or use RSVP (Resource Reservation Protocol) to establish specific
QoS-supported LSPs or traffic engineering-based LSPs. This chapter only discusses
the LSPs established with LDP, which will form full-connected LSP between PE
routers.
3 Routing information exchange between PE and CE
The internal connectivity between all the PEs is ensured via IGP (for example, RIP
and OSPF), so IGP should run at all interconnection interfaces and loopback
interfaces.
and OSPF), so IGP should run at all interconnection interfaces and loopback
interfaces.
4 LSP setup between PEs
LSPs should be set up between PEs for VPN data traffic forwarding with MPLS LSP.
The PE router which receives packets from CE and create label protocol stack is
called ingress LSR, while the BGP next hop (egress PE router) is egress LSR.
The PE router which receives packets from CE and create label protocol stack is
called ingress LSR, while the BGP next hop (egress PE router) is egress LSR.
5 Routing information exchange between PE and CE
A CE can learn remote VPN routes from the PE connected through static routes,
RIP, OSPF or EBGP.
RIP, OSPF or EBGP.
With the above-mentioned steps, reachable routes can be established between
CEs, for transmission of VPN private routing information over public network.
CEs, for transmission of VPN private routing information over public network.
RD
IPv4 address
...
ERT1
ERT2
...
ERTn
ERT: Export Route Targets
Import Route Targets:
( IRT1, IRT2, ... ,IRTm )
MPLS VPN Route