06463061 is referenced by 156 patents.

A service provider's routers (PE

1,

P

1,

P

2,

PE

2

) provide connections between and share routing information with routers (CE

1,

CE

2

) of a customer virtual private network (VPN) as well as routers of other customers' VPNs, which may have overlapping address spaces. A service provider's edge router (PE

1

) informed by the customer's router (CE

1

) that it will forward packets to a given prefix notifies the other edge router (PE

2

) that PE

1

can forward packets to that address prefix if the destination is in the VPN to which CE

1

belongs. PE

1

also tells PE

2

to tag any thus-destined packets with a particular tag T

3.

PE

2

stores this information in a forwarding information base that it separately keeps for that VPN so that when PE

2

receives from a router CE

2

in the same VPN a packet whose destination address has that prefix, it tags the packet as requested. But PE

2

also tags it with a tag T

2

that the router P

2

to which PE

2

first sends it has asked PE

2

to apply to packets to be sent to PE

1.

P

2

routes the packet in accordance with T

2,

sending it to P

1

after replacing T

2

with a tag T

1

that P

1

has similarly asked P

2

to use. P

1

removes T

1

from the packet and forwards it in accordance with T

1

to PE

1,

which in turn removes T

3

from the packet and forwards it in accordance with T

3

to CE

1.

In this manner, only the edge routers need to maintain separate routing information for separate VPNs.

Title
Shared communications network employing virtual-private-network identifiers
Application Number
9/232947
Publication Number
6463061 (B1)
Application Date
January 19, 1999
Publication Date
October 8, 2002
Inventor
Eric C Rosen
Arlington
MA, US
Yakov Rekhter
New Rochelle
NY, US
Agent
Cesari and McKenna
US
Assignee
Cisco Technology
CA, US
IPC
H04L 12/28
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