Prerequisites for 6PE
Redistribute PE-CE IGP IPv6 routes into core BGP and vice-versa
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Redistribute PE-CE IGP IPv6 routes into core BGP and vice-versa
eBGP as CE-PE is not supported. Static Routes, OSPFv3, ISIS, RIPv2 are supported as CE-PE.
6PE is a technique that provides global IPv6 reachability over IPv4 MPLS. It allows one shared routing table for all other devices. 6PE allows IPv6 domains to communicate with one another over the IPv4 without an explicit tunnel setup, requiring only one IPv4 address per IPv6 domain.
While implementing 6PE, the provider edge routers are upgraded to support 6PE, while the rest of the core network is not touched (IPv6 unaware). This implementation requires no reconfiguration of core routers because forwarding is based on labels rather than on the IP header itself. This provides a cost-effective strategy for deploying IPv6.The IPv6 reachability information is exchanged by PE routers using multiprotocol Border Gateway Protocol (mp-iBGP) extensions.
6PE relies on mp-iBGP extensions in the IPv4 network configuration on the PE router to exchange IPv6 reachability information in addition to an MPLS label for each IPv6 address prefix to be advertised. PE routers are configured as dual stacks, running both IPv4 and IPv6, and use the IPv4 mapped IPv6 address for IPv6 prefix reachability exchange. The next hop advertised by the PE router for 6PE and 6VPE prefixes is still the IPv4 address that is used for IPv4 L3 VPN routes. A value of ::FFFF: is prepended to the IPv4 next hop, which is an IPv4-mapped IPv6 address.
Ensure that you configure 6PE on PE routers participating in both the IPv4 cloud and IPv6 clouds.
BGP running on a PE router should establish (IPv4) neighborhood with BGP running on other PEs. Subsequently, it should advertise the IPv6 prefixes learnt from the IPv6 table to the neighbors. The IPv6 prefixes advertised by BGP would automatically have IPv4-encoded-IPv6 addresses as the nexthop-address in the advertisement.
To configure 6PE, complete the following steps:
Command or Action | Purpose | |
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Step 1 |
enable Example:
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Enables privileged EXEC mode.
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
ipv6 unicast-routing Example:
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Enables the forwarding of IPv6 unicast datagrams. |
Step 4 |
router bgp as-number Example:
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Enters the number that identifies the autonomous system (AS) in which the router resides. as-number —Autonomous system number. Range for 2-byte numbers is 1 to 65535. Range for 4-byte numbers is 1.0 to 65535.65535. |
Step 5 |
bgp router-id interface interface-id Example:
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Configures a fixed router ID for the local Border Gateway Protocol (BGP) routing process. |
Step 6 |
bgp log-neighbor-changes Example:
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Enables logging of BGP neighbor resets. |
Step 7 |
bgp graceful-restart Example:
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Enables the Border Gateway Protocol (BGP) graceful restart capability globally for all BGP neighbors. |
Step 8 |
neighbor { ip-address | ipv6-address | peer-group-name } remote-as as-number Example:
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Adds an entry to the BGP or multiprotocol BGP neighbor table.
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Step 9 |
neighbor { ip-address | ipv6-address | peer-group-name } update-source interface-type interface-number Example:
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Configures BGP sessions to use any operational interface for TCP connections. |
Step 10 |
address-family ipv6 Example:
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Enters address family configuration mode for configuring routing sessions, such as BGP, that use standard IPv6 address prefixes. |
Step 11 |
redistribute protocol as-number match { internal | external 1 | external 2 Example:
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Redistributes routes from one routing domain into another routing domain. |
Step 12 |
neighbor { ip-address | ipv6-address | peer-group-name } activate Example:
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Enables the exchange of information with a BGP neighbor. |
Step 13 |
neighbor { ip-address | ipv6-address | peer-group-name } send-label Example:
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Sends MPLS labels with BGP routes to a neighboring BGP router. |
Step 14 |
exit-address-family Example:
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Exits BGP address-family submode. |
Step 15 |
end Example:
|
Returns to privileged EXEC mode. |
PE Configuration |
CE Configuration |
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|
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BGP router identifier 1.1.1.1, local AS number 100
BGP table version is 34, main routing table version 34
4 network entries using 1088 bytes of memory
4 path entries using 608 bytes of memory
4/4 BGP path/bestpath attribute entries using 1120 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 2816 total bytes of memory
BGP activity 6/2 prefixes, 16/12 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
2.2.2.2 4 100 21 21 34 0 0 00:04:57 2
sh ipv route
IPv6 Routing Table - default - 7 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2
IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external
ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect
RL - RPL, O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1
OE2 - OSPF ext 2, ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
la - LISP alt, lr - LISP site-registrations, ld - LISP dyn-eid lA - LISP away
C 10:1:1:2::/64 [0/0]
via Vlan4, directly connected
L 10:1:1:2::1/128 [0/0]
via Vlan4, receive
LC 11:11:11:11::11/128 [0/0]
via Loopback1, receive
B 30:1:1:2::/64 [200/0]
via 33.33.33.33%default, indirectly connected
B 40:1:1:2::/64 [200/0]
via 44.44.44.44%default, indirectly connected
BGP table version is 112, local router ID is 11.11.11.11
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
t secondary path,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 10:1:1:2::/64 :: 0 32768 ?
*>i 30:1:1:2::/64 ::FFFF:33.33.33.33
0 100 0 ?
*>i 40:1:1:2::/64 ::FFFF:44.44.44.44
0 100 0 ?
*>i 173:1:1:2::/64 ::FFFF:33.33.33.33
2 100 0 ?
40:1:1:2::/64, epoch 6, flags [rib defined all labels]
recursive via 44.44.44.44 label 67
nexthop 1.20.4.2 Port-channel103 label 99-(local:147)
This table provides release and related information for features explained in this module.
These features are available on all releases subsequent to the one they were introduced in, unless noted otherwise.
Release |
Feature |
Feature Information |
---|---|---|
Cisco IOS XE Everest 16.6.1 |
IPv6 Provider Edge over MPLS (6PE) |
IPv6 Provider Edge over MPLS (6PE) provides global IPv6 reachability over IPv4 MPLS and allows one shared routing table for all other devices. |
Use Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.