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Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-13270-06
Chapter 39 Configuring IP Unicast Routing
Configuring Multi-VRF CE
participate in the same VPN. Each VPN is mapped to a specified VRF. After learning local VPN
routes from CEs, a PE router exchanges VPN routing information with other PE routers by using
internal BGP (IBPG).
•
Provider routers or core routers are any routers in the service provider network that are not attached
to CE devices.
With multi-VRF CE, multiple customers can share one CE, and only one physical link is used between
the CE and the PE. The shared CE maintains separate VRF tables for each customer and switches or
routes packets for each customer based on its own routing table. Multi-VRF CE extends limited PE
functionality to a CE device. It can then maintain separate VRF tables to extend the privacy and security
of a VPN to the branch office.
Figure 39-6
is an example of switches as multiple virtual CEs. This scenario is suited for customers who
have low bandwidth requirements for their VPN service, for example, small companies. In this case,
multi-VRF CE support is required in the switches. Because multi-VRF CE is a Layer 3 feature, each
interface in a VRF must be a Layer 3 interface.
Figure 39-6
Switches Acting as Multiple Virtual CEs
When the CE switch receives a command to add a Layer 3 interface to a VRF, it sets up the mapping
between the VLAN ID and the policy label (PL) in multi-VRF-CE-related data structures and adds the
VLAN ID and PL to the VLAN database.
When multi-VRF CE is configured, the Layer 3 forwarding table is virtually partitioned into two
sections:
•
The multi-VRF CE routing section contains the routes from different VPNs.
•
The global routing section contains routes to non-VPN networks, such as the Internet.
VLAN IDs from different VRFs are mapped to different policy labels, which are used to distinguish the
VRFs during processing. For each new VPN route learned, the Layer 3 setup function retrieves the policy
label by using the VLAN ID of the ingress port and inserts the policy label and the new route to the
multi-VRF CE routing section. If the packet is received from a routed port, the port internal VLAN ID
number is used; if the packet is received from an SVI, the VLAN number is used.
This is the packet-forwarding process in a multi-VRF-CE-enabled network:
•
When the switch receives a packet from a VPN, the switch looks up the routing table based on the
input policy label number. When a route is found, the switch forwards the packet to the PE.
•
When the ingress PE receives a packet from the CE, it performs a VRF lookup. When a route is
found, the router adds a corresponding MPLS label to the packet and sends it to the MPLS network.
VPN 1
VPN 2
VPN 1
VPN 2
CE2
PE1
PE2
Service
provider
CE1
CE = Customer-edge device
PE = Provider-edge device
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Содержание Catalyst Blade 3032
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Страница 50: ...lii Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide OL 13270 06 Preface ...
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