HCIE Datacom-ISIS双栈IPv6配置-WOLFLAB实验室

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IS-IS最初是为OSI网络设计的一种基于链路状态算法的动态路由协议。之后为了提供对IPv4的路由支持，扩展应用到IPv4网络，称为集成IS-IS。

随着IPv6网络的建设，同样需要动态路由协议为IPv6报文的转发提供准确有效的路由信息。IS-IS路由协议结合自身具有良好的扩展性的特点，实现了对IPv6网络层协议的支持，可以发现和生成IPv6路由。

IETF的draft-ietf-isis-ipv6-05中规定了IS-IS为支持IPv6所新增的内容。为了支持IPv6路由的处理和计算，IS-IS新增了两个TLV（Type-Length-Value）和一个新的NLPID（Network Layer Protocol Identifier）。

新增的两个TLV分别是：

• 236号TLV（IPv6 Reachability）：通过定义路由信息前缀、度量值等信息来说明网络的可达性。

• 232号TLV（IPv6 Interface Address）：它相当于IPv4中的“IP Interface Address”TLV，只不过把原来的32比特的IPv4地址改为128比特的IPv6地址。

NLPID是标识网络层协议报文的一个8比特字段，IPv6的NLPID值为142（0x8E）。如果IS-IS支持IPv6，那么向外发布IPv6路由时必须携带NLPID值。

实验：AR1和AR3运行ipv6的ISIS

R1配置如下：

[AR1]dis current-configuration

[V200R003C00]

ipv6

#

isis 1

 is-level level-2

 network-entity 49.0000.0000.0001.00

 #

 ipv6 enable topology standard

 #

interface GigabitEthernet0/0/0

 ipv6 enable

 ip address 1.1.13.1 255.255.255.0

 ipv6 address 2001:13::1/64

 isis enable 1

 isis ipv6 enable 1

#

interface GigabitEthernet0/0/1

 ip address 1.1.12.1 255.255.255.0

 isis enable 1

#

interface LoopBack0

 ipv6 enable

 ip address 1.1.1.1 255.255.255.255

 ipv6 address 2001::1/128

 isis enable 1

 isis ipv6 enable 1

此时R1和R3即建立的ISIS邻居即可以计算IPV4的路由也能计算IPV6的路由，ISIS部分IPV4的邻居或者是IPV6的邻居；

[AR1]dis isis peer verbose

                          Peer information for ISIS(1)

  System Id     Interface          Circuit Id       State HoldTime Type     PRI

-------------------------------------------------------------------------------

0000.0000.0003  GE0/0/0            0000.0000.0001.01 Up   22s      L2       64

  MT IDs supported     : 0(UP)

  Local MT IDs         : 0

  Area Address(es)     : 49

  Peer IP Address(es)  : 1.1.13.3       

  Peer IPv6 Address(es): FE80::2E0:FCFF:FEB9:5212

  Uptime               : 00:02:52

  Adj Protocol         : IPV4  IPV6

  Restart Capable      : YES

  Suppressed Adj       : NO

  Peer System Id       : 0000.0000.0003 

0000.0000.0002  GE0/0/1            0000.0000.0001.02 Up   29s      L2       64

  MT IDs supported     : 0(UP)

  Local MT IDs         : 0

  Area Address(es)     : 49

  Peer IP Address(es)  : 1.1.12.2       

  Uptime               : 00:15:20

  Adj Protocol         : IPV4

  Restart Capable      : YES

  Suppressed Adj       : NO

  Peer System Id       : 0000.0000.0002 

R1和R3也能学到对端环回口的路由：

[AR1]dis ipv6 routing-table protocol isis

Public Routing Table : ISIS

Summary Count : 1

ISIS Routing Table's Status : < Active >

Summary Count : 1

 Destination  : 2003::3                         PrefixLength : 128

 NextHop      : FE80::2E0:FCFF:FEB9:5212        Preference   : 15

 Cost         : 10                              Protocol     : ISIS-L2

 RelayNextHop : ::                              TunnelID     : 0x0

 Interface    : GigabitEthernet0/0/0            Flags        : D

ISIS Routing Table's Status : < Inactive >

Summary Count : 0

R1通告的实节点LSP如下：

[AR1]dis isis lsdb 0000.0000.0001.00-00 verbose

                        Database information for ISIS(1)

                        --------------------------------

                          Level-2 Link State Database

LSPID                 Seq Num      Checksum      Holdtime      Length  ATT/P/OL

-------------------------------------------------------------------------------

0000.0000.0001.00-00* 0x00000016   0xae49        1145          188     0/0/0  

 SOURCE       0000.0000.0001.00

 NLPID        IPV4

 NLPID        IPV6                                                                //新增NLPID

 AREA ADDR    49

 INTF ADDR    1.1.12.1

 INTF ADDR    1.1.1.1

 INTF ADDR    1.1.13.1

 INTF ADDR V6 2001::1                                                   //所有启用的了ISIS的IPV6接口地址    

 INTF ADDR V6 2001:13::1                      

 Topology     Standard                                                     //拓扑的类型是标准的，也就是单TOP                        

 NBR  ID      0000.0000.0001.02  COST: 10                  //IPV4和IPV6共用一个TOP结构

 NBR  ID      0000.0000.0001.01  COST: 10       

 IP-Internal  1.1.12.0        255.255.255.0    COST: 10       

 IP-Internal  1.1.1.1         255.255.255.255  COST: 0        

 IP-Internal  1.1.13.0        255.255.255.0    COST: 10       

 IPV6         2001::1/128                      COST: 0               //IPV6的网段信息

 IPV6         2001:13::/64                     COST: 10       

R1通告的LSP如下：

Frame 35: 205 bytes on wire (1640 bits), 205 bytes captured (1640 bits) on interface -, id 0

IEEE 802.3 Ethernet

Logical-Link Control

ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol

ISO 10589 ISIS Link State Protocol Data Unit

    PDU length: 188

    Remaining lifetime: 1199

    LSP-ID: 0000.0000.0001.00-00

    Sequence number: 0x0000001c

    Checksum: 0xa24f [correct]

    [Checksum Status: Good]

    Type block(0x03): Partition Repair:0, Attached bits:0, Overload bit:0, IS type:3

    Protocols supported (t=129, l=2)                               //NLPID有IPV4和IPV6

        Type: 129

        Length: 2

        NLPIDs: IP (0xcc), IPv6 (0x8e)

    Multi Topology (t=229, l=2)

        Type: 229

        Length: 2

        IPv4 Unicast Topology (0x000)                                        //单拓扑，IPV4和IPV6共用一个TOP

    Area address(es) (t=1, l=2)

    IS Reachability (t=2, l=23)

    IP Interface address(es) (t=132, l=12)

    IP Internal reachability (t=128, l=36)

    IPv6 Interface address(es) (t=232, l=32)                     //LSP中会将启用了isis的所有的全球单播地址携带在232 TLV里面，HELLO报文会将报文发送接口的link-local地址携带进去；

        Type: 232

        Length: 32

        IPv6 interface address: 2001::1

        IPv6 interface address: 2001:13::1

    IPv6 reachability (t=236, l=36)                                  //描述路由信息

        Type: 236

        Length: 36

        IPv6 Reachability: 2001::1/128

            Metric: 0

            0... .... = Distribution: Up                                             //DU bit

            .0.. .... = Distribution: Internal                           //内部路由就是internal，外部路由就是external，IPV4使用TLV来标识内部路由和外部路由，IPV6使用该bit；

            ..0. .... = Sub-TLV: No

            Prefix Length: 128

            IPv6 prefix: 2001::1

            no sub-TLVs present

        IPv6 Reachability: 2001:13::/64

            Metric: 10

            0... .... = Distribution: Up

            .0.. .... = Distribution: Internal

            ..0. .... = Sub-TLV: No

            Prefix Length: 64

            IPv6 prefix: 2001:13::

            no sub-TLVs present

ST和MT：

ST：默认就是ST，isis中进行邻居描述的时候用的system id进行SPT树的计算，跟IP没啥关系，IPV4地址和IPV6地址只是叶子挂上去；

如图所示：如果使用单TOP，如果RTB不支持，RTA访问RTC时走RTB，因为cost小，此时出现路由黑洞；

实验：将AR1和AR3之间的cost改成30

R1/R3：

interface GigabitEthernet0/0/0

 isis cost 30                  //将R1和R3互联接口的cost改成30，注意如果是ST，敲了isis ipv6 cost 30也不好使，因为ST只存在232和236描述路由信息，ST没有描述TOP信息的TLV，

此时IPV4和IPV6共用一个TOP，IPV4和IPV6都作为叶子挂在树干上；

此时R1和R3彼此就学不到对端的IPV6的isis路由了，但是R1和R3的LSDB还是完整的：

[AR1]dis ipv6 routing-table protocol isis

[AR1]

[AR1]dis isis lsdb 0000.0000.0003.00-00  verbose

                        Database information for ISIS(1)

                        --------------------------------

                          Level-2 Link State Database

LSPID                 Seq Num      Checksum      Holdtime      Length  ATT/P/OL

-------------------------------------------------------------------------------

0000.0000.0003.00-00  0x00000018   0xdba5        1130          188     0/0/0  

 SOURCE       0000.0000.0003.00

 NLPID        IPV4

 NLPID        IPV6

 AREA ADDR    49

 INTF ADDR    1.1.13.3

 INTF ADDR    1.1.23.3

 INTF ADDR    3.3.3.3

 INTF ADDR V6 2001:13::3                    

 INTF ADDR V6 2003::3                       

 Topology     Standard

 NBR  ID      0000.0000.0003.02  COST: 10       

 NBR  ID      0000.0000.0001.01  COST: 30       

 IP-Internal  1.1.23.0        255.255.255.0    COST: 10       

 IP-Internal  3.3.3.3         255.255.255.255  COST: 0        

 IP-Internal  1.1.13.0        255.255.255.0    COST: 30       

 IPV6         2003::3/128                      COST: 0        

 IPV6         2001:13::/64                     COST: 30       

R1发现，运行SPF算法，去往R3的2003::3/128下一跳是R2，但是R2没有运行IPV6，因为R2通告的实节点LSP，会携带NLPID，此时R1就算不出来路由了；

那此时怎么解决？

MT：多拓扑

为了MT的实现，新增了四个TLV

229：MT的标识

222：描述IPV6的TOP信息

235：多拓扑的IPV4可达信息                   //这个TLV一直没见到

237：多拓扑的IPV6可达信息

此时在R1和R3上开启多TOP的功能

R1/R3：

isis 1

 is-level level-2

 network-entity 49.0000.0000.0001.00

 #

 ipv6 enable topology ipv6

此时在R1上看：

[AR1]dis isis  peer

                          Peer information for ISIS(1)

  System Id     Interface          Circuit Id       State HoldTime Type     PRI

-------------------------------------------------------------------------------

0000.0000.0003* GE0/0/0            0000.0000.0001.01 Up   22s      L2       64

0000.0000.0002  GE0/0/1            0000.0000.0001.02 Up   26s      L2       64

*标识跟R3建立的是MT的邻居关系

[AR1]dis isis  lsdb 0000.0000.0001.00-00 verbose

                        Database information for ISIS(1)

                        --------------------------------

                          Level-2 Link State Database

LSPID                 Seq Num      Checksum      Holdtime      Length  ATT/P/OL

-------------------------------------------------------------------------------

0000.0000.0001.00-00* 0x00000027   0x4b70        998           207     0/0/0  

 SOURCE       0000.0000.0001.00

 NLPID        IPV4

 NLPID        IPV6

 AREA ADDR    49

 INTF ADDR    1.1.12.1

 INTF ADDR    1.1.1.1

 INTF ADDR    1.1.13.1

 INTF ADDR V6 2001::1                       

 INTF ADDR V6 2001:13::1                    

 Topology     Standard, IPV6

 NBR  ID      0000.0000.0001.02  COST: 10       

 NBR  ID      0000.0000.0001.01  COST: 30       

+MT NBR ID    0000.0000.0001.01  COST: 10                 MT: 2 (IPV6)

 IP-Internal  1.1.12.0        255.255.255.0    COST: 10       

 IP-Internal  1.1.1.1         255.255.255.255  COST: 0        

 IP-Internal  1.1.13.0        255.255.255.0    COST: 30       

 IPV6         2001::1/128                      COST: 0          MT: 2  

 IPV6         2001:13::/64                     COST: 10         MT: 2  

[AR1]dis isis lsdb 0000.0000.0003.00-00 ver

                        Database information for ISIS(1)

                        --------------------------------

                          Level-2 Link State Database

LSPID                 Seq Num      Checksum      Holdtime      Length  ATT/P/OL

-------------------------------------------------------------------------------

0000.0000.0003.00-00  0x0000001f   0xbfcb        990           207     0/0/0  

 SOURCE       0000.0000.0003.00

 NLPID        IPV4

 NLPID        IPV6

 AREA ADDR    49

 INTF ADDR    1.1.13.3

 INTF ADDR    1.1.23.3

 INTF ADDR    3.3.3.3

 INTF ADDR V6 2001:13::3                    

 INTF ADDR V6 2003::3                       

 Topology     Standard, IPV6

 NBR  ID      0000.0000.0003.02  COST: 10       

 NBR  ID      0000.0000.0001.01  COST: 30       

+MT NBR ID    0000.0000.0001.01  COST: 10                 MT: 2 (IPV6)

 IP-Internal  1.1.23.0        255.255.255.0    COST: 10       

 IP-Internal  3.3.3.3         255.255.255.255  COST: 0        

 IP-Internal  1.1.13.0        255.255.255.0    COST: 30       

 IPV6         2003::3/128                      COST: 0          MT: 2  

 IPV6         2001:13::/64                     COST: 10         MT: 2  

此时可以看到IPV4和IPV6的TOP就分开算了，R1和R3也能够算出来路由了：

[AR1]dis ipv6 routing-table protocol isis

Public Routing Table : ISIS

Summary Count : 1

ISIS Routing Table's Status : < Active >

Summary Count : 1

 Destination  : 2003::3                         PrefixLength : 128

 NextHop      : FE80::2E0:FCFF:FEB9:5212        Preference   : 15

 Cost         : 10                              Protocol     : ISIS-L2

 RelayNextHop : ::                              TunnelID     : 0x0

 Interface    : GigabitEthernet0/0/0            Flags        : D

AR1]ping ipv6 -a 2001::1 2003::3

  PING 2003::3 : 56  data bytes, press CTRL_C to break

    Reply from 2003::3

    bytes=56 Sequence=1 hop limit=64  time = 20 ms

    Reply from 2003::3

    bytes=56 Sequence=2 hop limit=64  time = 30 ms

    Reply from 2003::3

    bytes=56 Sequence=3 hop limit=64  time = 20 ms

R1开启多MT发送的LSP如下：

Frame 2483: 224 bytes on wire (1792 bits), 224 bytes captured (1792 bits) on interface -, id 0

IEEE 802.3 Ethernet

Logical-Link Control

ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol

ISO 10589 ISIS Link State Protocol Data Unit

    PDU length: 207

    Remaining lifetime: 1199

    LSP-ID: 0000.0000.0001.00-00

    Sequence number: 0x00000027

    Checksum: 0x4b70 [correct]

    [Checksum Status: Good]

    Type block(0x03): Partition Repair:0, Attached bits:0, Overload bit:0, IS type:3

    Protocols supported (t=129, l=2)                      //NLPID：IPV4和IPV6

        Type: 129

        Length: 2

        NLPIDs: IP (0xcc), IPv6 (0x8e)

    Multi Topology (t=229, l=4)                            //MT，IPV4和IPV6分别算

        Type: 229

        Length: 4

        IPv4 Unicast Topology (0x000)

        IPv6 Unicast Topology (0x002)

    Area address(es) (t=1, l=2)

    IS Reachability (t=2, l=23)

    Multi Topology IS Reachability (t=222, l=13)         //IPV6的TOP信息

        Type: 222

        Length: 13

        0000 .... .... .... = Reserved: 0x0

        .... 0000 0000 0010 = Topology ID: IPv6 routing topology (2)

        IS Neighbor: 0000.0000.0001.01

    IP Interface address(es) (t=132, l=12)

    IP Internal reachability (t=128, l=36)

    IPv6 Interface address(es) (t=232, l=32)                  //IPV6接口地址仍然存在

        Type: 232

        Length: 32

        IPv6 interface address: 2001::1

        IPv6 interface address: 2001:13::1

    Multi Topology Reachable IPv6 Prefixes (t=237, l=38)             //开启MT后IPV6的路由信息

        Type: 237

        Length: 38

        0000 .... .... .... = Reserved: 0x0

        .... 0000 0000 0010 = Topology ID: IPv6 routing topology (2)

        IPv6 Reachability: 2001::1/128

        IPv6 Reachability: 2001:13::/64

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