Vpn-Ipv4 Address And Route Distinguisher; Figure 17 Structure Of Vpn-Ipv4 Address - Zte ZXR10 8900 Series User Manual

VPN-IPv4 Address and Route
Distinguisher
Layer 3 VPN may be connected to private networks through Inter-
net, these private networks can use public or private addresses.
When private networks use private addresses, the addresses be-
tween different private networks may be repeated.
To avoid repetition of private addresses, public addresses can be
used in network equipment to replace private addresses. Solutions
are provided in RFC2547bis and it uses present private net ID to
create a new definite address.
This new address is one of the components in VPN-IPv4 address
family and is BGP address family of MP-BGP. In a VPN-IPv4 ad-
dress, there is a value used to differentiate different VPNs, called
Route Distinguisher (RD).
A VPN-IPv4 address is a 12-byte quantity composed of an 8-byte
Route Distinguisher followed by a 4-byte IPv4 address prefix. The
structure of VPN-IPv4 address is shown in
F 17 S
IGURE TRUCTURE OF
8-byte RD is composed of a 2-byte Type field and a 6-byte Value
field. Type field determines the lengths of the Value field's two sub-
fields (Administrator and Assigned Number), as well as semantics
of Administrator field. The functions of the fields are described as
follows:
� Type filed
It determines the lengths of other two domains.
If the value of the type field is 0, the administrator (ADM) sub-
field is four bytes and the Assignment Number (AN) subfield is
two bytes.
If the value of the type field is 1, the administrator (ADM) sub-
field is two bytes and the Assignment Number (AN) subfield is
four bytes.
� Administrator subfield
It identifies an administration allocation number.
If the value of the type field is 0, the administrator subfield
contains an IPv4 address. RFC2547bis recommends that the
IP address of a router (this address is normally configured as
router ID) should be used, and this address is a public address.
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Chapter 3 MPLS L3VPN Configuration
Figure
VPN-IP 4 A
V DDRESS
17.
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