如图所示,AR1和AR2位于Area10内,AR3位于Area20内。其中AR1为L1路由器,AR2为L1/2路由器,AR3为L2路由器。仙子AR1的Gi0/0/1接口上配置了2:1:1::1/64、2:1:2::1/64、2:1:3::1/64 3个全球单播IPv6地址。
为了减小网络中中其他路由器的路由表规模,在AR1上配置IS-IS IPv6聚合路由,只发布2:1:1::1/64、2:1:2::1/64、2:1:3::1/64 3个网段聚合后的路由2::/16。
本示例是在完成IS-IS IPv6基本功能配置的基础上,再在一L1路由器AR1上配置路由聚合,这样AR1在区域10内部向邻居路由器路由时,2:1:1::1/64、2:1:2::1/64、2:1:3::1/64这3个地址对应的网段路由被抑制发布,取而代之的是一条对应的聚合路由,所以AR2的L1 IS-IS路由表到时候会用2::/64替换2:1:1::1/64、2:1:2::1/64、2:1:3::1/64这3个网段的明细路由。由于L1路由缺省会渗透到L2区域,所以AR3上的情形也于AR2上的一样。
根据以上分析可得出本示例如下基本配置思路。
① 配置各路由器的接口IPv6地址。
② 配置各路由器的IS-IS iPv6基本功能。
③ 在AR1上配置向L1区域发布2::/64聚合路由。
1) 配置各路由器的接口IPv6地址
【AR1配置】
ipv6
#
interface GigabitEthernet0/0/0
ipv6 enable
ipv6 address 1::1/64
#
interface GigabitEthernet0/0/1
ipv6 enable
ipv6 address 2:1:1::1/64
ipv6 address 2:1:2::1/64
ipv6 address 2:1:3::1/64
#
【AR2配置】
ipv6
#
interface GigabitEthernet0/0/0
ipv6 enable
ipv6 address 1::2/64
#
interface GigabitEthernet0/0/1
ipv6 enable
ipv6 address 3::1/64
#
【AR3配置】
ipv6
#
interface GigabitEthernet0/0/0
ipv6 enable
ipv6 address 3::2/64
#
interface GigabitEthernet0/0/1
ipv6 enable
ipv6 address 4::1/64
#
2) 配置各路由器的IS-IS IPv6基本功能
假设AR1-AR3的系统ID分别为0000.0000.0001-0000.0000.0003,均使能缺省的1号IS-IS IPv6进程。其中AR1为L1路由、AR2为L1/2路由器、AR3为L2路由。
【AR1上的配置如下】
isis 1
is-level level-1
network-entity 10.0000.0000.0001.00
#
ipv6 enable topology standard
#
interface GigabitEthernet0/0/0
ipv6 enable
ipv6 address 1::1/64
isis ipv6 enable 1
#
interface GigabitEthernet0/0/1
ipv6 enable
ipv6 address 2:1:1::1/64
ipv6 address 2:1:2::1/64
ipv6 address 2:1:3::1/64
isis ipv6 enable 1
#
【AR2上的配置如下】
isis 1
network-entity 10.0000.0000.0002.00
#
ipv6 enable topology standard
#
interface GigabitEthernet0/0/0
ipv6 enable
ipv6 address 1::2/64
#
interface GigabitEthernet0/0/1
ipv6 enable
ipv6 address 3::1/64
isis ipv6 enable 1
isis circuit-level level-2
#
【AR3上的配置如下】
isis 1
is-level level-2
network-entity 20.0000.0000.0003.00
#
ipv6 enable topology standard
#
interface GigabitEthernet0/0/0
ipv6 enable
ipv6 address 3::2/64
isis ipv6 enable 1
#
interface GigabitEthernet0/0/1
ipv6 enable
ipv6 address 4::1/64
isis ipv6 enable 1
#
以配置好后,在没有配置IS-IS IPv6路由聚合功能前,在AR2、AR3上执行display isis route命令,查看查其IS-IS路由表,可以发现它们从AR1学到了3条连续网段路由,参加输出信息中的粗体字部分。
【AR2上】
<AR2>dis isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-1 Forwarding Table
--------------------------------
IPV6 Dest. ExitInterface NextHop Cost Flags
--------------------------------------------------------------------------
2:1:2::/64 GE0/0/0 FE80::2E0:FCFF:FEB3:781E 20 A/L/-
2:1:1::/64 GE0/0/0 FE80::2E0:FCFF:FEB3:781E 20 A/L/-
1::/64 GE0/0/0 Direct 10 D/L/-
2:1:3::/64 GE0/0/0 FE80::2E0:FCFF:FEB3:781E 20 A/L/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV6 Dest. ExitInterface NextHop Cost Flags
------------------------------------------------------------------------
4::/64 GE0/0/1 FE80::2E0:FCFF:FE9E:14FA 20 A/-/-
3::/64 GE0/0/1 Direct 10 D/L/-
1::/64 GE0/0/0 Direct 10 D/L/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
【AR3上】
<AR3>dis isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV6 Dest. ExitInterface NextHop Cost Flags
2:1:2::/6 GE0/0/0 FE80::2E0:FCFF:FEDD:38B0 30 A/-/-
4::/64 GE0/0/1 Direct 10 D/L/-
3:: GE0/0/0 Direct 10 D/L/-
2:1:1::/6 GE0/0/0 FE80::2E0:FCFF:FEDD:38B0 30 A/-/-
1::/ GE0/0/0 FE80::2E0:FCFF:FEDD:38B0 20 A/-/-
2:1:3:: GE0/0/0 FE80::2E0:FCFF:FEDD:38B0 30 A/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
3) 在AR1上配置IS-IS IPv6路由聚合
把2:1:1::1/64、2:1:2::1/64、2:1:3::1/64这3个地址对应的网段路由聚合成一条2::/64路由,因为AR1是在区域10内部,是L1路由器,所以它只能向L1区域分布。
[AR1]isis 1
[AR1-isis-1]ipv6 summary 2:: 16 level-1
在AR1上配置好路由聚合后,再在AR2和AR3上执行display isis route命令,查看其IS-IS路由表,可以发现原来的3条连续网段路由不见了,但多了一条2::/64路由,这时聚合路由,参见输出信息中的粗体字部分。由此可以证明,IS-IS IPv6路由聚合功能配置是成功的。
【AR2上】
<AR2>dis isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-1 Forwarding Table
--------------------------------
IPV6 Dest. ExitInterface NextHop Cost Flags
-------------------------------------------------------------------------
2::/16 GE0/0/0 FE80::2E0:FCFF:FEB3:781E 20 A/L/-
1::/64 GE0/0/0 Direct 0 D/L/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV6 Dest. ExitInterface NextHop Cost Flags
--------------------------------------------------------------------------
4::/64 GE0/0/1 FE80::2E0:FCFF:FE9E:14FA 20 A/-/-
3::/64 GE0/0/1 Direct 10 D/L/-
1::/64 GE0/0/0 Direct 10 D/L/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
【AR3上】
<AR3>dis isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV6 Dest. ExitInterface NextHop Cost Flags
------------------------------------------------------------------------
4::/64 GE0/0/1 Direct 10 D/L/-
3::/64 GE0/0/0 Direct 10 D/L/-
2::/16 GE0/0/0 FE80::2E0:FCFF:FEDD:38B0 30 A/-/-
1::/64 GE0/0/0 FE80::2E0:FCFF:FEDD:38B0 20 A/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
【说明】如果在AR2上配置对以上3网段进行路由聚合,且指定仅向L2区域发布,则仅会在AR3的IS-IS路由表中存在2::/16这条聚合路由,在AR2上仍有3条明细路由,也不会向Area10中的路由器进行发布。