思科6RD-从IPv4快速过渡到IPv6部署，从理论到实现讲解

标签：nal   mobile   区别   cape   ges   user   round   出接口   connected   

6RD简介

6RD是IPv6快速部署（IPv6 Rapid Deployment）的简称，其对应标准为RFC5569，6RD是在6to4基础上发展起来的一种IPv6网络过渡技术方案。通过在现有IPv4网络中增加6RD-BR，向使用IPv6的用户提供IPv6接入；在IPv6用户的家庭网关和6RD网关之间建立6in4隧道，从而实现在IPv4网络提供IPv6服务的能力.
6RD在向IPv6过渡的过程中已经取得了部分成功，因为它容易实施，扩展性强而且可靠，同时它还是无状态的。
6RD是6to4自动隧道的扩展技术，部署更加灵活。它使得运行商通过已经部署完毕的IPv4网络提供IPv6服务，当然也是通过最常用的把IPv6封装在IPv4中实现。
6RD和6to4自动隧道的区别：
6RD不需要特定的使用2002::/16,它可以使用运行商自己的地址块，这大大的增加了实施的便利性。
32位的IPv4的目标地址需要在IPv6的有效负荷重承载

图7-12 6RD示意图
如图7-12所示，CE侧为客户的IPv6单播服务，CEs之间可以实现客户的IPv6互访，也可以通过BR（边界中继设备）访问BR后的IPv6网络。数据穿越运营商的现有IPv4网络。
我们在图7-14中实施6RD，其中R3和R6为CE，而R5为BR设备。各个设备上的环回口5模拟IPv6主机。
图7-13为6RD隧道的地址格式，后64位是客户自己的地址空间，前64位是授权的地址空间，其中前32位是运行商的前缀，紧更着后边32位是IPv4地址，这32位中分为IPv4通用地址前缀和IPv4通用后缀（本案例通用后缀为0.0.0.0）。

图7-13 6RD隧道的地址格式

图7-14 6RD实施拓扑

步骤1.完成IPv4网络

三台设备的配置相同，启用了eigrp作为承载路由的协议
r```
outer eigrp 90
network 172.16.0.0
CE-R3#show ip eigrp neighbors
EIGRP-IPv4 Neighbors for AS(90)
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 172.16.123.1 Et0/0 13 00:49:29 10 100 0 6
0 172.16.123.2 Et0/0 14 00:49:30 8 100 0 5
CE-R3#show ip route eigrp
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route

• • replicated route, % - next hop override

Gateway of last resort is not set

  172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks

D 172.16.0.1/32 [90/409600] via 172.16.123.1, 00:49:38, Ethernet0/0
D 172.16.0.2/32 [90/409600] via 172.16.123.2, 00:49:38, Ethernet0/0
环回口必须数据可达，因为IPv6的通信其实是6RD隧道的源地址之间的通信，而在本案例中，我们6RD隧道的源地址为环回接口
CE-R3#ping 172.16.0.1 source loopback 0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.0.1, timeout is 2 seconds:
Packet sent with a source address of 172.16.0.3
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/5/6 ms
CE-R3#ping 172.16.0.2 source loopback 0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.0.2, timeout is 2 seconds:
Packet sent with a source address of 172.16.0.3
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/4/6 ms

## 步骤2.实施6RD隧道以及实现IPv6的路由
BR-R5
ipv6 general-prefix 6RD 6rd Tunnel1 //6RD隧道1的前缀通过通用前缀获得
!
interface Tunnel1
 no ip address
 no ip redirects
 ipv6 address 6RD ::/128 //隧道的地址通过6RD获得
 tunnel source Loopback0 //隧道的源地址为环回口，而在前边的实施中已经使得环回口数据可达
 tunnel mode ipv6ip 6rd //实施隧道的模式为6RD
 tunnel 6rd ipv4 prefix-len 16 //定义6RD隧道的通用IPv4前缀长度为16，没有定义通用IPv4后缀
 tunnel 6rd prefix 2003:AABB::/32 //自定义6RD隧道的前32位
!
ipv6 route 2003:AABB::/32 Tunnel1 //定义静态路由，到达2003:AABB::/32前缀的出接口为隧道1
!
interface Loopback5
 no ip address
 ipv6 address 2003:8888::1/64 //该接口默认IPv6互联网地址
CE-R6:
ipv6 general-prefix 6RD 6rd Tunnel1
!
interface Tunnel1
 no ip address
 no ip redirects
 ipv6 address 6RD ::/128
 tunnel source Loopback0
 tunnel mode ipv6ip 6rd
 tunnel 6rd ipv4 prefix-len 16
 tunnel 6rd prefix 2003:AABB::/32
 tunnel 6rd br 172.16.0.1 //在客户侧的CE设备上定义BR，可以通过BR实现互联网访问
!
ipv6 route 2003:AABB::/32 Tunnel1 //到达IPv6的通用前缀出接口为隧道1
ipv6 route ::/0 Tunnel1 2003:AABB:1:: //实施到达IPv6的默认路由出接口为隧道1，下一跳中继到BR的6RD隧道的48位通用前缀。
!
interface Loopback5
 no ip address
 ipv6 address 2003:AABB:3:1::1/64
CE-R3
ipv6 general-prefix 6RD 6rd Tunnel1
!
interface Tunnel1
 no ip address
 no ip redirects
 ipv6 address 6RD ::/128
 tunnel source Loopback0
 tunnel mode ipv6ip 6rd
 tunnel 6rd ipv4 prefix-len 16
 tunnel 6rd prefix 2003:AABB::/32
 tunnel 6rd br 172.16.0.1
!
ipv6 route 2003:AABB::/32 Tunnel1
ipv6 route ::/0 Tunnel1 2003:AABB:1::
!
interface Loopback5
 no ip address
 ipv6 address 2003:AABB:2:1::1/64
验证6RD隧道和IPv6路由
CE-R2#show tunnel 6rd 
Interface Tunnel1:
  Tunnel Source: 172.16.0.2
  6RD: Operational, V6 Prefix: 2003:AABB::/32
       V4 Prefix, Length: 16, Value: 172.16.0.0
       V4 Suffix, Length: 0, Value: 0.0.0.0
       Border Relay address: 172.16.0.1
  General Prefix: 2003:AABB:2::/48
CE-R3#show tunnel 6rd 
Interface Tunnel1:
  Tunnel Source: 172.16.0.3
  6RD: Operational, V6 Prefix: 2003:AABB::/32
       V4 Prefix, Length: 16, Value: 172.16.0.0
       V4 Suffix, Length: 0, Value: 0.0.0.0
       Border Relay address: 172.16.0.1
  General Prefix: 2003:AABB:3::/48
BR-R1#show tunnel 6rd 
Interface Tunnel1:
  Tunnel Source: 172.16.0.1
  6RD: Operational, V6 Prefix: 2003:AABB::/32
       V4 Prefix, Length: 16, Value: 172.16.0.0
       V4 Suffix, Length: 0, Value: 0.0.0.0
  General Prefix: 2003:AABB:1::/48 //BR设备得到的通用路由前缀
CE-R3#show ipv6 route
IPv6 Routing Table - default - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
       H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
       IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
       ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect
       O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2, ls - LISP site
       ld - LISP dyn-EID, a - Application
S   ::/0 [1/0]
     via 2003:AABB:1::, Tunnel1
S   2003:AABB::/32 [1/0]
     via Tunnel1, directly connected
LC  2003:AABB:3::/128 [0/0]
     via Tunnel1, receive
C   2003:AABB:3:1::/64 [0/0]
     via Loopback5, directly connected
L   2003:AABB:3:1::1/128 [0/0]
     via Loopback5, receive
L   FF00::/8 [0/0]
     via Null0, receive
CE-R2#show ipv6 route
IPv6 Routing Table - default - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
       H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
       IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
       ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect
       O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2, ls - LISP site
       ld - LISP dyn-EID, a - Application
S   ::/0 [1/0]
     via 2003:AABB:1::, Tunnel1
S   2003:AABB::/32 [1/0]
     via Tunnel1, directly connected
LC  2003:AABB:2::/128 [0/0]
     via Tunnel1, receive
C   2003:AABB:2:1::/64 [0/0]
     via Loopback5, directly connected
L   2003:AABB:2:1::1/128 [0/0]
     via Loopback5, receive
L   FF00::/8 [0/0]
     via Null0, receive
CE-R3#ping 2003:8888::1 source lo5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2003:8888::1, timeout is 2 seconds:
Packet sent with a source address of 2003:AABB:3:1::1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/6 ms
!
CE-R2#ping 2003:8888::1 source lo5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2003:8888::1, timeout is 2 seconds:
Packet sent with a source address of 2003:AABB:2:1::1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms

IPv6主机已经可以通信，那么报文又是如何封装的呢，读者可以通过图7-15查看

图7-15 6RD隧道的封装解析

![](https://s1.51cto.com/images/blog/201903/22/94e2ff752d2e689be931ea1d3e7f1b77.png?x-oss-process=image/watermark,size_16,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_100,g_se,x_10,y_10,shadow_90,type_ZmFuZ3poZW5naGVpdGk=)

思科6RD-从IPv4快速过渡到IPv6部署，从理论到实现讲解

标签：nal   mobile   区别   cape   ges   user   round   出接口   connected   

原文地址：https://blog.51cto.com/enderjoe/2367434