From: Kenneth Wygand (KWygand@customonline.com)
Date: Sat Jul 17 2004 - 20:48:25 GMT-3
Thanks for the posting Mike!
I definitely helps us visualize and reinforce the concepts when we can actually see the output. So thanks again for your post!
Ken
________________________________
From: Mike Calhoon [mailto:mcalhoon27@earthlink.net]
Sent: Sat 7/17/2004 6:44 PM
To: Kenneth Wygand; 'Lord, Chris'; ccielab@groupstudy.com
Subject: RE: 3550 COnnectivity
Ken,
I thought it had something to do with proxy-arp. You are right about the arp table. Before I put in the default-gateway command the destination IP showed up in the arp table, but did not after the command was entered. The thing about my setup is there are two possible gateways on the VLAN. I suppose it shouldn't matter which one it uses though, but I guess I didn't feel like choosing. Here are the outputs...
SW1 is on VLAN62...ip address is 168.1.62.7.
Before default-gateway...
Rack1SW1#ping 168.1.4.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 168.1.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 116/316/1116 ms
Rack1SW1#show arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 168.1.4.4 0 0010.7b7f.1202 ARPA Vlan62
Internet 168.1.62.7 - 000a.8a9a.2800 ARPA Vlan62
After a clear arp and default-gateway to 168.1.62.2
Rack1SW1#ping 168.1.4.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 168.1.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 116/316/1116 ms
Rack1SW1#show arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 168.1.62.7 - 000a.8a9a.2800 ARPA Vlan62
Internet 168.1.62.2 0 0010.7b7f.1202 ARPA Vlan62
Thanks,
Mike
________________________________
From: Kenneth Wygand [mailto:KWygand@customonline.com]
Sent: Saturday, July 17, 2004 6:23 PM
To: Mike Calhoon; Lord, Chris; ccielab@groupstudy.com
Subject: RE: 3550 COnnectivity
Mike,
Without specifying the "ip default-gateway", your 3550 will default to using proxy-arp to resolve your IP addresses to MAC addresses. If your attached router (on the VLAN where your switch's IP address is) supports proxy-arp, it will resolve and your ping will succeed.
You should have entries if you do a "show arp" when using proxy-arp, but I don't believe those entries will exist when crossing VLANs if you have a default gateway configured (just your default gateway will be in your local arp table).
If you can, try it out both ways and post your outputs! :)
Hope this helps,
Ken
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