RE: [nsp] dot1q/isl "encapsulation failed"

From: F. David Sinn (dsinn@dsinn.seanet.com)
Date: Thu Mar 08 2001 - 17:30:16 EST


The configuration you show should work for interfaces that support dot1q.
The single FE port I/O module for the 7200 doesn't support dot1q to my
memory, but does support ISL (I have a setup running it right now).

I would check on the Cat side and make sure that it is recognizing that the
port is a trunk port. Possibly you need to hardcode the config:

set trunk 1/1 on isl 1-1005

And confirm that the VLAN's in question are active on the switch.

Baring that, I would suggest setting an encapsulation on the .1 interface
just to be safe.

What version of IOS are you running?

David

-----Original Message-----
From: Dmitri Kalintsev [mailto:dek@hades.uz]
Sent: Thursday, March 08, 2001 1:21 PM
To: cisco-nsp@puck.nether.net
Subject: [nsp] dot1q/isl "encapsulation failed"

Hi guys,

I'm having rather hard time finding what's wrong in seemingly stupid
situation:

!
interface FastEthernet0/0
 ip address <real ip address> 255.255.255.128
 no ip directed-broadcast
 full-duplex
!
interface FastEthernet0/0.1
 no ip redirects
 no ip directed-broadcast
!
interface FastEthernet0/0.77
 encapsulation dot1Q 77
 ip address 10.1.1.5 255.255.255.252
 no ip directed-broadcast
!

(I've tried no ip address on maininterface and f0/0.1 in dit1q vlan 1,
result is the same).

7206-vpn-test#ping 10.1.1.6

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.6, timeout is 2 seconds:

19:41:37: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
sending
19:41:37: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
encapsulation failed.
19:41:39: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
sending
19:41:39: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
encapsulation failed.
19:41:41: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
sending
19:41:41: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
encapsulation failed.
19:41:43: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
sending
19:41:43: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
encapsulation failed.
19:41:45: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
sending
19:41:45: IP: s=10.1.1.5 (local), d=10.1.1.6 (FastEthernet0/0.77), len 100,
encapsulation failed.
Success rate is 0 percent (0/5)

I've tried to change dot1q to ISL, and result is the same, "encapsulation
failed". FE works fine, if I don't use VLAN's. I've tried different IOS
sets, too. Oh, yes. And a different router. First was 7206vxr with npe300
and dual FE IO controller, this current one is 7206 with npe200 and vanilla
IO controller. No difference.

Switch side I presume is not guilty, as this very same switch runs a few
dot1 trunks to other switches without problem. Switch is Cat2948, so it only
supports dot1q trunks. Switch and router perfectly see each other on cdp
neighbor list, too.

7206-vpn-test#sh int f0/0.77
FastEthernet0/0.77 is up, line protocol is up
  Hardware is DEC21140A, address is 0004.de2f.8000 (bia 0004.de2f.8000)
  Internet address is 10.1.1.5/30
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation 802.1Q Virtual LAN, Vlan ID 77.
  ARP type: ARPA, ARP Timeout 04:00:00

It seem to recognize that it's a VLAN interface, too...

There is nothing really I can think of now, and what the hell should I think
of? This is a simple configuration, as simple as it gets, and I had it
working in dozens of other places. :( Any ideas?

SY,

--
D.K.



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