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28267
May 2nd, 2008 11:00
VLAN across Point-to-Point T1
Ok, here is what I am wanting to try:
PC6248 >> Cisco 2800 Router <---T1---> Cisco 2800 Router >> PC6224
I have 4 vlans that would go across this link: 8,100,102, and 103. And this is how I think I would need to setup the vlans:
6248:
switchport mode trunk
switchport trunk allowed vlan add 8
switchport trunk allowed vlan add 100
switchport trunk allowed vlan add 102
switchport trunk allowed vlan add 103
2800:
interface FastEthernet0/1.1
encapsulation dot1q 8
ip address 192.168.8.10 255.255.254.0
interface FastEthernet0/1.2
encapsulation dot1q 100
ip address 192.168.100.10 255.255.255.0
interface FastEthernet0/1.3
encapsulation dot1q 102
ip address 192.168.102.10 255.255.255.0
interface FastEthernet0/1.4
encapsulation dot1q 103
ip address 192.168.103.10 255.255.255.0
Ok, so I am thinking that I would need to add these to both ends. Would this work?
Thank you,
Travis
sentinel-master
345 Posts
0
May 2nd, 2008 16:00
No is the short answer for multiple reasons :
(1) A T1 link will have a HDLC(Cisco default) or PPP encapsulation format, different to Ethernet frame and therefore have to re-foramted to the outbound interface type.
(2) Essentially you are descbribing trying to Bridge VLANs over the WAN - which is not a good idea - as your "expensive WAN link" would be swamped or used up with LAN multicast and broadcast traffic.....rather than useful data traffic.
(3) If you try to do it the way you describe, you will get strange routing problems - as you can't have the same networks in two different geographical locations at the same time.....you'll get black holing or split subnet scenarios and lost connectivity.
(4) If you wish to "route" aross the WAN - which is the config you have actually annotated above - then yes you can do this......although the remote VLANS woudl have to be completely different subnets - i.e not just copied from Site A.
So "Route" not "Bridge"
ttrout
2 Posts
0
May 5th, 2008 14:00
Thank you for your response. I was basically thinking that, but wasn't sure. What we are trying to do is replicate virtual machines to a CoLo and then be able to turn them on their incase of an emergency. I realize I could just script them to change their IP's at bootup, but we have a few servers that really don't like their IP to change mainly SharePoint.
Thanks again,
Travis