Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Trunk via Long Reach Ethernet (LRE)


we have following problem with a WS-C2912-LRE-Switch and 575-CPE-Modem:

We tried to connect another switch by using a LRE-Line as trunk with 802.1q-encapsulation in order to have various VLANs on this switch (No fibre to this building).

That works, as long the packet-size is small (ICMP, Telnet, SNMP etc.).

If the packet-size is big (HTTP, 1500 bytes in IP) it doesn't work.

I think, the problem is, that the 802.1q-trunk-fame is 4 bytes bigger than the Standard-Ethernet-Frame.

Setting the MTU-Size bigger on the LRE-Interface didn't work.

Has anybody got an idea what we could do to make it work? Thank you.

Rolf Fischer


Re: Trunk via Long Reach Ethernet (LRE)

This is most probably due to the bug ID "CSCdx84385". This defect in IOS 12.0(5)WC4 and but it is not appeared in IOS 12.0(5)WC2. So that, you can downgrade to this IOS or wait for next IOS version.

New Member

Re: Trunk via Long Reach Ethernet (LRE)

Thank you very much! I didn' t believe it's a software-problem but in fact it is. Unfortuantly the older version dosen't know the RADIUS-commands we require too. So we've to wait for the next version.

Kind regards

Rolf Fischer