ping,也是一種網絡層協議,在執行ping的操作中也需要查找路由表,可以理解為網絡設備是使用距離目標地址“最近”的一個接口的IP作為源地址發起的icmp request,也可以理解為 當前路由器或者交換機獲悉目標地址路由的那個接口的IP地址
舉例來說明:
1.如果交換機僅是一個三層設備,配置了svi管理地址,以及default-gateway,這種情況下,毫無疑問是svi的接口地址
2.如果交換機是三層設備,配置有多個svi地址,三層地址或者環回地址
-交換機ping 連接到此交換機vlan10下麵的一台PC,使用的是vlan10的接口地址
-交換機ping 一個通過動態路由協議能獲悉路由的一個地址(見下麵測試情況). -交換機通過默認路由去往目的地址,也是一樣的情況,不做贅述
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以下為一台65ping一台測試的交換機10.1.3.4,通過查路由表可以看到65從T7/4接口獲悉該目標地址的路由,那麼ping的時候就會使用T7/4的接口地址作為源地址發起icmp-request
65-1>sh ip route 10.1.3.4
Routing entry for 10.1.3.0/24
Known via "ospf 1", distance 110, metric 2, type intra area
Last update from 10.254.2.81 on TenGigabitEthernet7/4, 7w0d ago
Routing Descriptor Blocks:
* 10.254.2.81, from 10.254.1.36, 7w0d ago, via TenGigabitEthernet7/4
Route metric is 2, traffic share count is 1
65-1>sh ip int b | in 7/4
TenGigabitEthernet7/4 10.254.2.82 YES manual up up
65-1>ping 10.1.3.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.3.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/2 ms
65-1>
--
TEST_PoE#sh ip int b
Vlan10 10.1.3.4 YES manual up up
TEST_PoE#debug ip icmp
ICMP packet debugging is on
TEST_PoE#terminal monitor
TEST_PoE#
Dec 31 2020 11:18:38.012 CST: ICMP: echo reply sent, src 10.1.3.4, dst 10.254.2.82, topology BASE, dscp 0 topoid 0
Dec 31 2020 11:18:38.012 CST: ICMP: echo reply sent, src 10.1.3.4, dst 10.254.2.82, topology BASE, dscp 0 topoid 0
Dec 31 2020 11:18:38.019 CST: ICMP: echo reply sent, src 10.1.3.4, dst 10.254.2.82, topology BASE, dscp 0 topoid 0
Dec 31 2020 11:18:38.019 CST: ICMP: echo reply sent, src 10.1.3.4, dst 10.254.2.82, topology BASE, dscp 0 topoid 0
Dec 31 2020 11:18:38.022 CST: ICMP: echo reply sent, src 10.1.3.4, dst 10.254.2.82, topology BASE, dscp 0 topoid 0
TEST_PoE#un all
All possible debugging has been turned off
嗯