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Home > Archive > CCNA > March 2001 > Trunking
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| danieloh 2001-03-24, 6:17 am |
| Hi all,
"The benefit of trunking is that a server, for example, can be in two braodcast domains at the same time. this will stop users from having to cross a layer-3 to log in and use the server."-from a sybex CCNA study guide.
Would anyone explain this?
Thanks.
Daniel. | |
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| quote:
Originally posted by danieloh
Hi all,
"The benefit of trunking is that a server, for example, can be in two braodcast domains at the same time. this will stop users from having to cross a layer-3 to log in and use the server."-from a sybex CCNA study guide.
Would anyone explain this?
Thanks.
Daniel.
A server with a trunk capable NIC is connected to a switch port. The switch port is trunking 2 VLAN's. Vlan10 is IP network 172.16.10.0/24. Vlan11 is 172.16.11.0/24. The two VLAN's are, of course, 2 separate broadcast domains, and 2 separate IP networks.
Normally, the server could be in only 1 broadcast domain. Users in other broadcast domains would have to go across a router, AKA a layer 3 device, to use the server.
With the trunk-capable server, though, you give the server an IP address in each VLAN. You configure the switch to trunk both VLAN's on the port to the server. This makes the server a member of both VLAN's (=both broadcast domains = both IP networks) at the same time. Users in both VLAN's can access the server over the switch, without crossing a router.
This is cool, because latency is much higher across a router than a switch.
More could be said. I will add that using separate IP networks for each VLAN is good design, but you could conceivably design the network so that you split 1 IP network into 2 broadcast domains/VLAN's, and give the server 1 IP address and trunk it for both VLAN's. If that's confusing, focus on the stuff above first.
HTH,
doctorcisco |
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