how to config trunk between router2511 and cat3524?

[lordy]

I made as follow on cat3524:

conf t

int fa 0/1

switchport mode trunk

switchport trunk isl

exit

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And how to do on router 2511 ethernet 0?

[wukunpeng]

cisco2511 does not support ISL or 802.1Q encapsulation.

You can use 175x or 26xx,they support 802.1Q protocol.

[bsivasub]

Check this URL out.

http://www.cisco.com/warp/public/473/50.shtml

Trunking over 10mb is probably not supported.