Thanks dgviuc, but it still doesn't work. The router just treats the space character as the end of a string. xxxx#delete flash0:/CME\ 10.5.0\ GUI                                           ^ % Invalid input detected at '^' marker. ... View more

In the GNS environment ，the MPLS mtu value won't adjust and I have got an ICMP message to notify that the payload size is greater than the outgoing link and of course the packet was dropped. But in PPPoE environment，the packet was merely dropped without notifying the source. ... View more

Hi, Jody By “MPLS uses a 1504-byte Ethernet frame and so the payload remains 1500 bytes” you mean that when I deploy MPLS, the mtu capacity of the “mpls ip” interface will automatically change to fit the length of the payload？because there could be more than one label being added. ... View more

Yeah, I agree with M SEB, PMTUD mechanism uses ICMP to adjust the mtu size, and on the other hand, Adjust-mss works like an agent. The reason why a router would send an ICMP message back to the source is that the payload size of a packet is bigger than the mtu value of the outgoing interface.  In my opinion, both MPLS and PPPoE need to add extra tag to the frame, on is label with 4 bytes, and the other is "PPPoE header plus PPP header" with 8 bytes.   Why in the MPLS case, a router could find the mtu problem and send back the ICMP message, while in the PPPoE case, the router seems not able ?   Is that because the "PPPoE head plus PPP header" is considered as the layer 2 encapsulation so that the mtu calculation is started with the IP layer and in the MPLS case, label is calculated in mtu along with IP layer and above or is that because of the virtual interface used in PPPoE  ... View more

Hi, Yes we are talking about the second scenario, for security concern I had changed the IP address, hope you could understand. VLAN 101 was created on N3K-1 for testing, and the device 10.129.4.1 doesn't have the route to reach 10.10.101.0/24. Only N3K-1 knows about it. So I think in the second scenario, when two N3Ks forms a group, the standby device doesn't handle the VMAC.   N3K-2#  show mac address-table vlan 11 | include 0000.0c07.ac0b * 11       0000.0c07.ac0b    dynamic   610        F    F  Po1   I have checked again, and the flag is *.   on N3K-1 no mac information for vlan 11 about VMAC   I used the "show mac address-table" command to check out again, and I could only see dynamic entries. ... View more

And I have also found a relevant bug, but is for N5K, and the condition is hsrp not working. more details https://tools.cisco.com/bugsearch/bug/CSCts46891 I just think that the condition I had met is also a bug, because when I have the same topology, similar ip addresses, but change the devices to 3560-X, everything works well. ... View more

on N3K-2 N3K-2# show ip route 10.10.101.1 IP Route Table for VRF "default" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] '%<string>' in via output denotes VRF <string> Route not found N3K-2# show ip route 0.0.0.0 IP Route Table for VRF "default" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] '%<string>' in via output denotes VRF <string> 0.0.0.0/0, ubest/mbest: 1/0     *via 10.129.4.1, [1/0], 3d07h, static N3K-2#show hsrp interface vlan 11 Vlan11 - Group 11 (HSRP-V1) (IPv4)   Local state is Standby, priority 120 (Cfged 120), may preempt     Forwarding threshold(for vPC), lower: 1 upper: 120    Hellotime 3 sec, holdtime 10 sec   Next hello sent in 2.123000 sec(s)   Virtual IP address is 10.10.11.254 (Cfged)   Active router is 10.10.11.252, priority 150 expires in 0.173000 sec(s)   Standby router is local    Authentication text "cisco"   Virtual mac address is 0000.0c07.ac0b (Default MAC)   3 state changes, last state change 3d07h   IP redundancy name is hsrp-Vlan11-11 (default) N3K-2# show mac address-table vlan 11 | include 0000.0c07.ac0b * 11       0000.0c07.ac0b    dynamic   610        F    F  Po1   no mac information for VLAN 101 on N3K-2   on N3K-1 N3K-1# show hsrp interface vlan 11 Vlan11 - Group 11(HSRP-V1) (IPv4)   Local state is Active, priority 150 (Cfged 150), may preempt     Forwarding threshold(for vPC), lower: 1 upper: 150    Hellotime 3 sec, holdtime 10 sec   Next hello sent in 1.705000 sec(s)   Virtual IP address is 10.10.11.254 (Cfged)   Active router is local   Standby router is 10.10.11.253 , priority 120 expires in 2.865000 sec(s)   Authentication text "cisco"   Virtual mac address is 0000.0c07.ac0b (Default MAC)   1 state changes, last state change 3d07h   IP redundancy name is hsrp-Vlan11-11 (default)   no mac information for vlan 11 about VMAC   N3K-1# show hsrp brief                       P indicates configured to preempt.                      | Interface   Grp Prio P State    Active addr      Standby addr     Group addr Vlan11      11  150  P Active   local            10.10.11.253    10.10.11.254    (conf) ... View more

Thanks for your reply, I had assumed the same before I had another scenario yesterday. In this case, N3K-1 keeps on to be the active device of VLAN 11 and I have also created a new VLAN 101 on N3K-1 with IP address 10.10.101.1/24. Since N3K-2 which is in standby state doesn't has the route to 10.10.101.0/24, the packet with VLAN 11 VMAC to be the destination would be dropped if N3K-2 handled it. But in my test, PC had got ICMP replies from N3K-1 which means that the packet had got through the HSRP standby device in layer-2. ... View more

Also the switchport mode and trunk etherchannel state are checked, one uplink on N3K-3 is blocked because of the STP, all normal. ... View more

N3K-1: inter vlan 11 ip add 10.10.11.252 255.255.255.0 hsrp 11 ip 10.10.11.254 priority 150 preempt   N3K-2: inter vlan 11 ip add 10.10.11.253 255.255.255.0 hsrp 11 ip 10.10.11.254 priority 120 preempt   N3K-3: inter vlan 11 ip add 10.10.11.251 255.255.255.0 hsrp 11 ip 10.10.11.254 ... View more