From: Muizebelt Danny (Danny.Muizebelt@osiatis.at)
Date: Thu Jan 25 2007 - 06:11:39 ART
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I think you didn't get an arp resolution for the 172.16.34.4 address, thatbs why the encapsulation failed because there is no L3 to L2 mapping.
The reason why there is no arp resolution could be a problem with your trunk, is it up? Is vlan 30 defined on both switches? Is the spanning tree working properly?
Another thing I wanted to point out, if you statically configure duplex settings on one side and leave the other side on auto then the auto side will fall back to default half-duplex. Statically configuring duplex settings switches off the auto negotiation. So either both sides on auto or both statically configured.
Danny Muizebelt
CCIE #17353
- -----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Michael Zuo
Sent: Donnerstag, 25. JC$nner 2007 08:22
To: ccielab groupstudy
Subject: ICMP showing encapsulation failed
Hi group,
I am scratching my head on this one (probably something basic), please
help! And thanks in advance....
R3(f0/1)---------(f0/4)CAT1(f0/14)-----------(f0/14)CAT2(f0/5)----------
- -----R4(f0/0)
When I ping from R3 to R4, I get encapsulation failed message on R3:
R3(config-if)#do ping 172.16.34.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.34.4, timeout is 2 seconds:
2d07h: IP: tableid=0, s=172.16.34.3 (local), d=172.16.34.4
(FastEthernet0/1), ro
uted via RIB
2d07h: IP: s=172.16.34.3 (local), d=172.16.34.4 (FastEthernet0/1), len
100, send
ing
2d07h: IP: s=172.16.34.3 (local), d=172.16.34.4 (FastEthernet0/1), len
100, enca
psulation failed.
2d07h: IP: tableid=0, s=172.16.34.3 (local), d=172.16.34.4
(FastEthernet0/1), ro
uted via RIB
2d07h: IP: s=172.16.34.3 (local), d=172.16.34.4 (FastEthernet0/1), len
100, send
Ing
Configuration:
R3:
=======
R3(config-router)#do sh run int f0/1
Building configuration...
Current configuration : 96 bytes
!
interface FastEthernet0/1
ip address 172.16.34.3 255.255.255.0
duplex auto
speed auto
end
R3(config-router)#
CAT1:
========
CAT1(config)#do sh run int f0/4
Building configuration...
Current configuration : 97 bytes
!
interface FastEthernet0/4
switchport access vlan 30
switchport mode access
duplex full
end
CAT1(config)#do sh run int f0/14
Building configuration...
Current configuration : 137 bytes
!
interface FastEthernet0/14
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1,20,30,40
switchport mode trunk
CAT1(config-if)#do sh run int vlan 30
Building configuration...
Current configuration : 63 bytes
!
interface Vlan30
ip address 172.16.34.10 255.255.255.0
end
CAT2:
CAT2(config-if)#do sh run int f0/5
Building configuration...
Current configuration : 97 bytes
!
interface FastEthernet0/5
switchport access vlan 30
switchport mode access
duplex full
end
CAT2(config-if)#do sh run int f0/14
Building configuration...
Current configuration : 137 bytes
!
interface FastEthernet0/14
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1,20,30,40
switchport mode trunk
end
CAT2(config-if)#
R4
=======
R4(config-router)#do sh run int f0/0
Building configuration...
Current configuration : 96 bytes
!
interface FastEthernet0/0
ip address 172.16.34.4 255.255.255.0
duplex auto
speed auto
end
R4(config-router)#
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