I am hoping that someone will take pity on me and point out where I went wrong in configuring the following. This is for my home network, but it was an ambitious excuse to teach myself about networking. I'm in this far and I don't want to give up, but I am stuck.
Equipment:
Cisco 1921 router
Cisco SG-300-28 switch
Motorola SB-6121 cable modem
Various devices connected to the switch and depending on DHCP
I simulated all of this in Packet Tracer and I thought I had a pretty good grasp of the concepts, but I seem to be missing something when it comes to configuring my actual equipment. (Of course Packet Tracer doesn't have an SG-300 switch, so I suspect that is where my problem lies.)
I have spent many hours working to solve this myself, so I will try to provide information that will hopefully make this easier for an expert to spot easily.
I have attached the running configs for the router and the switch.
The SB6121 is connected to Comcast. The 1921 is connected to the SB6121 and I am able to get an IP for the router via DHCP.
I am trying to setup a router on a stick configuration even though the SG300 is a layer3 device. I have defined several VLANs, but interVlan routing is not working the way they did in Packet Tracer. Unless I put all switchports on VLAN 99, the devices cannot ping each other.
From 1921 router:
I can ping an external IP address
router-bsmnt-1921#ping 8.8.8.8
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/11/12 ms
DNS seems to be working as well.
router-bsmnt-1921#ping google.com
Translating "google.com"...domain server (1.1.1.1) [OK]
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 216.58.192.206, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/9/12 ms
From switch:
I can ping an external IP address
switch-bsmnt-sg300#ping 216.58.192.206
Pinging 216.58.192.206 with 18 bytes of data:
18 bytes from 216.58.192.206: icmp_seq=1. time=0 ms
18 bytes from 216.58.192.206: icmp_seq=2. time=0 ms
18 bytes from 216.58.192.206: icmp_seq=3. time=0 ms
18 bytes from 216.58.192.206: icmp_seq=4. time=0 ms
----216.58.192.206 PING Statistics----
4 packets transmitted, 4 packets received, 0% packet loss
round-trip (ms) min/avg/max = 0/0/0
But DNS is not working from the switch.
switch-bsmnt-sg300#ping google.com
% Host not found in DNS database
From a Mac connected to VLAN 99, with DHCP IP assigned from POOL-MANAGEMENT
I can ping 216.58.192.206
Traceroute makes an attempt to get to an external IP, but it is really slow.
{52} ~->traceroute 172.217.6.4
traceroute to 172.217.6.4 (172.217.6.4), 64 hops max, 52 byte packets
1 192.168.99.1 (192.168.99.1) 1.243 ms 1.053 ms 0.539 ms
2 96.120.25.189 (96.120.25.189) 9.171 ms 9.506 ms 8.980 ms
3 162.151.90.133 (162.151.90.133) 9.618 ms 9.735 ms 9.308 ms
4 68.86.188.82 (68.86.188.82) 9.438 ms 9.565 ms 9.494 ms
etc,
So the 1921 can connect to the internet and I can ping router interfaces from the SG300, but things are fundamentally broken internally.
1. Why can't the switch use DNS?
2. Why can't any device attached to the switch do anything beyond ping? I even tried putting IP addresses into the web browser, but that traffic doesn't seem to flow.
3. What did I do wrong with the inter-VLAN routing?
4. Why does the 1921 only serve DHCP when switchports are assigned to VLAN 99? Any other VLAN does not get an IP address. This is probably related to #3.
I know this is a lot to ask and I greatly appreciate any assistance you are willing to offer. I'm willing to do the work to learn this, but this is my first time and my mistakes are not yet obvious to me.
Thanks,
Don Zouras
