Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated:
1
00:00:00,000 --> 00:00:02,000 align:middle line:84%
Here’s my local PC
2
00:00:02,000 --> 00:00:06,000 align:middle line:84%
if I type ip config I can see my PCs IP address
3
00:00:06,000 --> 00:00:09,000 align:middle line:84%
and I can see the default gateway
4
00:00:09,000 --> 00:00:13,000 align:middle line:84%
my PC will send traffic to the default gateway
5
00:00:13,000 --> 00:00:20,000 align:middle line:84%
for any IP addresses not in the 192.168.56.0 subnet.
6
00:00:20,000 --> 00:00:24,000 align:middle line:84%
so as an example, if I ping google.com
7
00:00:24,000 --> 00:00:30,000 align:middle line:84%
that traffic is going via my default gateway
8
00:00:30,000 --> 00:00:35,000 align:middle line:84%
in the same way, I could telnet to a router.
9
00:00:35,000 --> 00:00:39,000 align:middle line:84%
here’s a Cisco router that I’ve got in my lab.
10
00:00:39,000 --> 00:00:42,000 align:middle line:84%
And if I type the command sh ip route
11
00:00:42,000 --> 00:00:45,000 align:middle line:84%
I can see the routing table of the router.
12
00:00:45,000 --> 00:00:48,000 align:middle line:84%
The router has directly connected networks.
13
00:00:48,000 --> 00:00:51,000 align:middle line:84%
So C is directly connected networks
14
00:00:51,000 --> 00:01:02,000 align:middle line:84%
as an example 192.168.56.0/24 is directly connected on this interface F0/0
15
00:01:02,000 --> 00:01:12,000 align:middle line:84%
so if I ping 192.168.56.1 that traffic is going to be sent out F0/0
16
00:01:12,000 --> 00:01:17,000 align:middle line:84%
because that network is directly connected to this interface.
17
00:01:17,000 --> 00:01:25,000 align:middle line:84%
Packets will traffic to 192.168.58.0 will be forwarded out of interface 0/1
18
00:01:25,000 --> 00:01:32,000 align:middle line:84%
notice this route S and * this is a candidate default route
19
00:01:32,000 --> 00:01:38,000 align:middle line:84%
in other words this static route is the default route that a router gonna use.
20
00:01:38,000 --> 00:01:41,000 align:middle line:84%
If I look at the running configuration of this router
21
00:01:41,000 --> 00:01:46,000 align:middle line:84%
and then include only lines that have IP router in them.
22
00:01:46,000 --> 00:01:50,000 align:middle line:84%
I can see this command was added to the router
23
00:01:50,000 --> 00:02:00,000 align:middle line:84%
so I type IP router 0.0.0.0 0.0.0.0 and then 192.168.56.1
24
00:02:00,000 --> 00:02:04,000 align:middle line:84%
This portion is saying that we are adding a default route
25
00:02:04,000 --> 00:02:06,000 align:middle line:84%
to the IP routing table of the router
26
00:02:06,000 --> 00:02:11,000 align:middle line:84%
with the gateway of last resort being 192.168.56.1
27
00:02:11,000 --> 00:02:18,000 align:middle line:84%
so basically this router will forward traffic to 192.168.56.1
28
00:02:18,000 --> 00:02:21,000 align:middle line:84%
for any networks not in it's routing table.
29
00:02:21,000 --> 00:02:23,000 align:middle line:84%
So once again sh ip route
30
00:02:23,000 --> 00:02:34,000 align:middle line:84%
shows me I have the 3 network 192.168.58, 192.68.56 192.168.97 in the routing table
31
00:02:34,000 --> 00:02:39,000 align:middle line:84%
but I don’t have as an example a route for google.com.
32
00:02:39,000 --> 00:02:47,000 align:middle line:84%
Google’s IP address is 216.58.213.100 that’s not in the routing table
33
00:02:47,000 --> 00:02:54,000 align:middle line:84%
but I was able to ping that address because of this entry in the routing table.
34
00:02:54,000 --> 00:03:02,000 align:middle line:84%
In other words, the local router forwarded traffic to 192.168.56.1
35
00:03:02,000 --> 00:03:06,000 align:middle line:84%
to firstly get to the DNS server 8.8.8.8
36
00:03:06,000 --> 00:03:14,000 align:middle line:84%
and secondly, to ping Google.com we can see that by using the traceroute command.
37
00:03:14,000 --> 00:03:18,000 align:middle line:84%
So let's trace route to Google.com
38
00:03:18,000 --> 00:03:26,000 align:middle line:84%
notice the first hop is 192.168.56.1 the local gateway of last resort
39
00:03:26,000 --> 00:03:33,000 align:middle line:84%
traffic is then sent out into the internet to get to google.com
40
00:03:33,000 --> 00:03:36,000 align:middle line:84%
so my traffic is being forwarded from router to router
41
00:03:36,000 --> 00:03:40,000 align:middle line:84%
until it gets to 216.58.213.100
42
00:03:40,000 --> 00:03:48,000 align:middle line:84%
this stars or * indicates that the router is not replying back
43
00:03:48,000 --> 00:03:51,000 align:middle line:84%
to the ICMP messages sent to it.
44
00:03:51,000 --> 00:03:54,000 align:middle line:84%
So ICMP maybe drop as an example
45
00:03:54,000 --> 00:03:59,000 align:middle line:84%
but the point to take note of is based on the IP routing table
46
00:03:59,000 --> 00:04:07,000 align:middle line:84%
on this router, the gateway of last resort or the default gateway is 192.168.56.1
47
00:04:07,000 --> 00:04:10,000 align:middle line:84%
this static route has been added to the routing table
48
00:04:10,000 --> 00:04:15,000 align:middle line:84%
and I could remove that by typing no ip route
49
00:04:15,000 --> 00:04:23,000 align:middle line:84%
Selecting the route so now when I type sh ip route
50
00:04:23,000 --> 00:04:29,000 align:middle line:84%
notice the static route that was their previously has now been removed
51
00:04:29,000 --> 00:04:31,000 align:middle line:84%
so now if try and ping google.com
52
00:04:31,000 --> 00:04:37,000 align:middle line:84%
the DNS resolution is failing and we won't be able to ping google.com
53
00:04:37,000 --> 00:04:43,000 align:middle line:84%
because we can't resolve the DNS name to IP address of Google.com
54
00:04:43,000 --> 00:04:47,000 align:middle line:84%
in this case, it's re-using the cache entry
55
00:04:47,000 --> 00:04:51,000 align:middle line:84%
and is sending traffic to 216.58.213.100
56
00:04:51,000 --> 00:04:55,000 align:middle line:84%
but notice the pings fail, we had a 0 success rate.
57
00:04:55,000 --> 00:05:01,000 align:middle line:84%
If I add this static route back again
58
00:05:01,000 --> 00:05:05,000 align:middle line:84%
and type sh ip route static route is back
59
00:05:05,000 --> 00:05:09,000 align:middle line:84%
and now when we ping Google.com the ping succeeds.
60
00:05:09,000 --> 00:05:13,000 align:middle line:84%
So static routes are still used quite heavily
61
00:05:13,000 --> 00:05:17,000 align:middle line:84%
especially on routers at remotes site or small sites.
62
00:05:17,000 --> 00:05:19,000 align:middle line:84%
Here’s my router at home.
63
00:05:19,000 --> 00:05:23,000 align:middle line:84%
This is the 192.168.56.1 router
64
00:05:23,000 --> 00:05:26,000 align:middle line:84%
that’s my Cisco router had as it's default gateway
65
00:05:26,000 --> 00:05:32,000 align:middle line:84%
and this router will also have a default gateway connecting it to the Internet.
66
00:05:32,000 --> 00:05:36,000 align:middle line:84%
So I'll log in if I look at the broadband connection
67
00:05:36,000 --> 00:05:39,000 align:middle line:84%
notice my local router has this IP address
68
00:05:39,000 --> 00:05:45,000 align:middle line:84%
and the default gateway is set to the IP address, primary DNS and secondary DNS
69
00:05:45,000 --> 00:05:49,000 align:middle line:84%
are set to these values, so my home broadband router
70
00:05:49,000 --> 00:05:53,000 align:middle line:84%
or DSL router has its own default gateway.
71
00:05:53,000 --> 00:06:01,000 align:middle line:84%
This Cisco router is forwarding traffic to the BTDSL router using this static route
72
00:06:01,000 --> 00:06:06,000 align:middle line:84%
and the BT router is forwarding traffic to this default gateway.
73
00:06:06,000 --> 00:06:11,000 align:middle line:84%
Every router makes its own decision on where to forward traffic to
74
00:06:11,000 --> 00:06:16,000 align:middle line:84%
hence following the hop by hop paradigm.
8683
Can't find what you're looking for?
Get subtitles in any language from opensubtitles.com, and translate them here.