diff --git a/d36-EIGRP.md b/d36-EIGRP.md index f371cb5..ae25aae 100644 --- a/d36-EIGRP.md +++ b/d36-EIGRP.md @@ -1754,3 +1754,34 @@ P 10.1.1.0/24, 1 successors, FD is 128256 via Connected, Loopback1 ... [Truncated Output] + +在路由表中,汇总路由是直接连接到`Null0`接口上的。该路由有着一个默认为5的管理距离数值(a default administrative distance value of 5)。下面的输出对此进行了演示: + +``` +R1#show ip route 10.0.0.0 255.0.0.0 +Routing entry for 10.0.0.0/8 + Known via “eigrp 150”, distance 5, metric 128256, type internal + Redistributing via eigrp 150 + Routing Descriptor Blocks: + * directly connected, via Null0 + Route metric is 128256, traffic share count is 1 + Total delay is 5000 microseconds, minimum bandwidth is 10000000 Kbit + Reliability 255/255, minimum MTU 1514 bytes + Loading 1/255, Hops 0 +``` + +在EIGRP完成自动汇总时,路由器将对汇总路由进行通过,从而抑制了那些更为具体路由的通告(When EIGRP performs automatic summarisation, the router advertises the summary route and suppresses the more specific routes)。换句话说,在汇总路由得以通告时,那些更为具体的前缀,在发往EIGRP邻居的更新中就被省略了(the more specific prefixes are suppressed in updates to EIGRP neighbours)。这一点可通过查看路由器R2上的路由表,加以验证,如下所示: + +``` +R2#show ip route eigrp +D 10.0.0.0/8 [90/2298856] via 150.1.1.1, 00:29:05, Serial0/0 +``` + +这种默认行为在一些基本的网络,比如上图36.15中演示的网络中,运作不错。但其可能在不连续网络,那种由两个分离的主要网络所组成的网络中,如下图36.16中所演示的,有着不利影响(However, it can have an adverse impact in a discontiguous network, which comprises a major network that separates another major network): + + +*图 36.16 -- 不连续网络* + +参考图36.16中所演示的图例,一个主要的`150.1.0.0/16`网络将这里的两个主要的`10.0.0.0/8`网络分开了。在开启自动汇总时,路由器R1与R2将把`10.1.1.0/24` + +> **译者注**:本小节及前面小节中所提到的主要网络(the major network),是指按网络大类分的网络,也就是A、B、C、D及E类网络。 diff --git a/images/3616.png b/images/3616.png new file mode 100644 index 0000000..2b73d4a Binary files /dev/null and b/images/3616.png differ