Let’s imagine you are an IP engineer and suddenly found increasing number of “TTL exceeded” packets on your router. Your first thought is “what the hell is it? How to find a source of these packets?”

Take it easy. You will know how to investigate such issue on Huawei router.

[labnario]display ip statistics
  Input:     sum               2783201      local               2321967
             bad protocol            0      bad format                0
             bad checksum            0      bad options               0
             discard srr             0      TTL exceeded         494196
  Output:    forwarding              0      local                886008
             dropped                 0      no route                  0
  Fragment:  input                   0      output                    0
             dropped                 0
             fragmented              0      couldn't fragment         0
  Reassembling:sum                   0      timeouts                  0

As you can see there are “TTL exceeded” packets. “Display ip statistics” command shows packets that are directed to CPU. Don’t mix it up with packets found on the interface. For example, you don’t have dropped packets on the interface but “display ip statistics” shows such packets.

What does it mean “TTL exceeded”?

It means the router receives packets with TTL=1.

What happens if it receives such packets?

It sends timeout-icmp packets.

We can check it using the following command:

[labnario]display icmp statistics
  Input: bad formats            0      bad checksum                     0
         echo                3108      destination unreachable        294
         source quench          0      redirects                        0
         echo reply             0      parameter problem                0
         timestamp              0      information request              0
         mask requests          0      mask replies                     0
         time exceeded          0
         Mping request          0      Mping reply                      0
  Output:echo                   0      destination unreachable          0
         source quench          0      redirects                        0
         echo reply          3108      parameter problem                0
         timestamp              0      information reply                0
         mask requests          0      mask replies                     0
         time exceeded     494196
         Mping request          0      Mping reply                      0

When you compare both outputs you will see that “TTL exceeded = time exceeded“.

And now how to find the source of these packets:

Feb 14 2012 09:08:08.250.1 labnario IP/7/debug_icmp:Slot=3;ICMP Send: ttl-exceeded(Type=11, Code=0), Src = 10.222.143.13, Dst = 172.16.20.88; Original IP header: Pro = 17, Src = 172.16.20.88, Dst = 10.222.143.113, First 8 bytes = B5E400A1 002C9D0D

As you can see debugging ICMP packets is helpful in this case.

I have come across link flapping protection feature recently. It is available on S5700 switches. It looks like it is a new feature on Huawei switches. I had not met it in older hardware versions. That’s why I decided to write a few words about it. Unfortunatelly, although this command is available in Huawei network simulator eNSP, it does not work properly. But maybe you will have possibility check it on your real devices.

Port flapping (port going UP and DOWN continually) can be caused by a faulty cable, link failure, active/standby switchover, port hardware failure, etc. Frequent status changes on an interface can lead to:

• STP topology recalculation and changes,
• ARP entries updates,
• dynamic routing instability and convergence problems.

All these issues can negatively affect switch performance and should be avoided.

Link Flapping Protection is a feature that can be implemented on an interface to solve problems caused by the flapping port or link. It checks the interface flapping frequency and link flapping detection interval. If the number of interface flapping times reaches the limit, in a specified period, the interface is shut down.

How to configure Link Flapping Protection? Please see below:

<labnarioSW1>sys
Enter system view, return user view with Ctrl+Z.
[labnarioSW1]int e0/0/1
[labnarioSW1-Ethernet0/0/1]port link-flap protection enable

By default this functionality is disabled on the interface. When enabled, default link flapping interval is set to 10 seconds and the number of flapping events is set to 5. This can be easily changed using the following commands:

[labnarioSW1-Ethernet0/0/1]port link-flap threshold 6
[labnarioSW1-Ethernet0/0/1]port link-flap interval 18

To bring the interface back to UP state, manual interface undo shutdown command is required or automatic error-down auto-recovery feature, described a few weeks ago.

Let’s keep going and try to configure BGP local preference attribute using route-policy.

We can take full advantage of topology and configuration from the last post: “BGP default local preference in Huawei CLI“.

1. Assure full connectivity based on the attached topology (look at the previous article).
2. Configure Loopback 10 and Loopback 20 on router AR4.
3. Import all Loopback interfaces of router AR4 to BGP.

After we configure locpref attributes:

• Traffic directed to network 111.111.111.111/32 is leaving AS100 through AR2 router.
• Traffic directed to network 222.222.222.222/32 is leaving AS100 through AR3 router.
• Keep local preference 100 for all other traffic.

Let’s come to the point.

Configure Loopbacks interfaces on AR4 router:

[AR4]dis current-configuration interface loopback
#
interface LoopBack0
 ip address 4.4.4.4 255.255.255.255 
#
interface LoopBack10
 ip address 111.111.111.111 255.255.255.255 
#
interface LoopBack20
 ip address 222.222.222.222 255.255.255.255 
#

Import configured networks into BGP:

[AR4]bgp 200
[AR4-bgp]import-route direct

Check IP and BGP routing tables of AR1 router:

[AR1]dis ip rout
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
         Destinations : 20       Routes : 21       

Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

        1.1.1.1/32  Direct  0    0           D   127.0.0.1       LoopBack0
        2.2.2.2/32  OSPF    10   1           D   10.1.1.2        GigabitEthernet0/0/0
        3.3.3.3/32  OSPF    10   1           D   10.1.2.2        GigabitEthernet0/0/1
        4.4.4.4/32  IBGP    255  0          RD   150.1.1.2       GigabitEthernet0/0/0
       10.1.1.0/30  Direct  0    0           D   10.1.1.1        GigabitEthernet0/0/0
       10.1.1.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
       10.1.1.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
       10.1.2.0/30  Direct  0    0           D   10.1.2.1        GigabitEthernet0/0/1
       10.1.2.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
       10.1.2.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
       10.1.3.0/30  OSPF    10   2           D   10.1.2.2        GigabitEthernet0/0/1
                    OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
100.100.100.100/32  Direct  0    0           D   127.0.0.1       LoopBack100
111.111.111.111/32  IBGP    255  0          RD   150.1.1.2       GigabitEthernet0/0/0
      127.0.0.0/8   Direct  0    0           D   127.0.0.1       InLoopBack0
      127.0.0.1/32  Direct  0    0           D   127.0.0.1       InLoopBack0
127.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
      150.1.1.0/30  OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
      150.2.2.0/30  OSPF    10   2           D   10.1.2.2        GigabitEthernet0/0/1
222.222.222.222/32  IBGP    255  0          RD   150.1.1.2       GigabitEthernet0/0/0
255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0

[AR1]dis bgp routing-table 

 BGP Local router ID is 1.1.1.1 
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete

 Total Number of Routes: 9
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>i  4.4.4.4/32         150.1.1.2       0          100        0      200?
 * i                     150.2.2.2       0          100        0      200?
 *>   100.100.100.100/32 0.0.0.0         0                     0      i
 *>i  111.111.111.111/32 150.1.1.2       0          100        0      200?
 * i                     150.2.2.2       0          100        0      200?
 *>i  150.1.1.0/30       2.2.2.2         0          100        0      i
 *>i  150.2.2.0/30       3.3.3.3         0          100        0      i
 *>i  222.222.222.222/32 150.1.1.2       0          100        0      200?
 * i                     150.2.2.2       0          100        0      200?

As you can see all traffic is leaving AS100 through AR2 router.

Configure 3 ACLs on AR2 and AR3 routers:

• The first one permits source IP of Loopback 10 of router AR4.
• The second one permits source IP of Loopback 20 of router AR4.
• The third one permits all other networks.

[AR2]acl number 2000  
[AR2-acl-basic-2000] rule 5 permit source 111.111.111.111 0 
[AR2]acl number 2500  
[AR2-acl-basic-2500] rule 5 permit source 222.222.222.222 0 
[AR2]acl number 2600  
[AR2-acl-basic-2600] rule 5 permit 
[AR2-acl-basic-2600]

[AR3]acl number 2000  
[AR3-acl-basic-2000] rule 5 permit source 111.111.111.111 0 
[AR3]acl number 2500  
[AR3-acl-basic-2500] rule 5 permit source 222.222.222.222 0 
[AR3]acl number 2600  
[AR3-acl-basic-2600] rule 5 permit

Configure route-policy, named locpref, on AR2 and AR3 routers:

[AR2]route-policy locpref permit node 10 
[AR2-route-policy] if-match acl 2000 
[AR2-route-policy] apply local-preference 300 
[AR2-route-policy]qu
[AR2]route-policy locpref permit node 20 
[AR2-route-policy] if-match acl 2500 
[AR2-route-policy] apply local-preference 200 
[AR2-route-policy]qu
[AR2]route-policy locpref permit node 30 
[AR2-route-policy] if-match acl 2600 
[AR2-route-policy] apply local-preference 100 
[AR2-route-policy]

[AR3]route-policy locpref permit node 10 
[AR3-route-policy] if-match acl 2000 
[AR3-route-policy] apply local-preference 200
[AR3-route-policy]qu
[AR3]route-policy locpref permit node 20 
[AR3-route-policy] if-match acl 2500 
[AR3-route-policy] apply local-preference 300 
[AR3-route-policy]qu
[AR3]route-policy locpref permit node 30 
[AR3-route-policy] if-match acl 2600 
[AR3-route-policy] apply local-preference 100 
[AR3-route-policy]

Assign locpref route-policy to BGP peers on AR2 and AR3 routers:

[AR2]bgp 100
[AR2-bgp]peer 1.1.1.1 route-policy locpref export

[AR3]bgp 100
[AR3-bgp]peer 1.1.1.1 route-policy locpref export

Let’s check IP and BGP routing tables of AR1 router again:

[AR1]dis ip routing-table 
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
         Destinations : 20       Routes : 21       

Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

        1.1.1.1/32  Direct  0    0           D   127.0.0.1       LoopBack0
        2.2.2.2/32  OSPF    10   1           D   10.1.1.2        GigabitEthernet0/0/0
        3.3.3.3/32  OSPF    10   1           D   10.1.2.2        GigabitEthernet0/0/1
        4.4.4.4/32  IBGP    255  0          RD   150.1.1.2       GigabitEthernet0/0/0
       10.1.1.0/30  Direct  0    0           D   10.1.1.1        GigabitEthernet0/0/0
       10.1.1.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
       10.1.1.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
       10.1.2.0/30  Direct  0    0           D   10.1.2.1        GigabitEthernet0/0/1
       10.1.2.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
       10.1.2.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
       10.1.3.0/30  OSPF    10   2           D   10.1.2.2        GigabitEthernet0/0/1
                    OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
100.100.100.100/32  Direct  0    0           D   127.0.0.1       LoopBack100
111.111.111.111/32  IBGP    255  0          RD   150.1.1.2       GigabitEthernet0/0/0
      127.0.0.0/8   Direct  0    0           D   127.0.0.1       InLoopBack0
      127.0.0.1/32  Direct  0    0           D   127.0.0.1       InLoopBack0
127.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
      150.1.1.0/30  OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
      150.2.2.0/30  OSPF    10   2           D   10.1.2.2        GigabitEthernet0/0/1
222.222.222.222/32  IBGP    255  0          RD   150.2.2.2       GigabitEthernet0/0/1
255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0

[AR1]dis bgp rout

 BGP Local router ID is 1.1.1.1 
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete

 Total Number of Routes: 9
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>i  4.4.4.4/32         150.1.1.2       0          100        0      200?
 * i                     150.2.2.2       0          100        0      200?
 *>   100.100.100.100/32 0.0.0.0         0                     0      i
 *>i  111.111.111.111/32 150.1.1.2       0          300        0      200?
 * i                     150.2.2.2       0          200        0      200?
 *>i  150.1.1.0/30       2.2.2.2         0          100        0      i
 *>i  150.2.2.0/30       3.3.3.3         0          100        0      i
 *>i  222.222.222.222/32 150.2.2.2       0          300        0      200?
 * i                     150.1.1.2       0          200        0      200?

Finally we did what we wanted to do. Our route-policy is working properly and traffic directed to Loopback 10 of AR4 router is going through AR2. Traffic directed to Loopback 20 of AR4 is going through AR3. For remaing traffic, local preference attribute is not to be taken into account for choosing the best path.

Let’s assume that we have a topology like in below picture:

1. AR1, AR2 and AR3 are in AS 100.
2. AR4 is in AS 200.
3. Loopback 100 of router AR1 and loopback 0 of router AR4 are advertised by BGP.

What we want to do is to configure default local preference attribute, which will determine the optimal route, for traffic that leaves AS 100. In our case, the whole traffic leaving AS 100 will go through AR3.

If a BGP device obtains multiple routes from different IBGP peers and these routes have different next hops to the same destination, the BGP device will select the route with the greatest Local_Pref value.

If you want to recall how to configure BGP, just go to “basic BGP in Huawei CLI“.

Check IP routing and BGP routing tables of router AR1:

[AR1]dis ip rout
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
         Destinations : 18       Routes : 18       

Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

        1.1.1.1/32  Direct  0    0           D   127.0.0.1       LoopBack0
        2.2.2.2/32  OSPF    10   1           D   10.1.1.2        GigabitEthernet0/0/0
        3.3.3.3/32  OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
        4.4.4.4/32  IBGP    255  0          RD   150.1.1.2       GigabitEthernet0/0/0
       10.1.1.0/30  Direct  0    0           D   10.1.1.1        GigabitEthernet0/0/0
       10.1.1.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
       10.1.1.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
       10.1.2.0/30  Direct  0    0           D   10.1.2.1        GigabitEthernet0/0/1
       10.1.2.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
       10.1.2.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
       10.1.3.0/30  OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
100.100.100.100/32  Direct  0    0           D   127.0.0.1       LoopBack100
      127.0.0.0/8   Direct  0    0           D   127.0.0.1       InLoopBack0
      127.0.0.1/32  Direct  0    0           D   127.0.0.1       InLoopBack0
127.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
      150.1.1.0/30  OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
      150.2.2.0/30  OSPF    10   3           D   10.1.1.2        GigabitEthernet0/0/0
255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0

[AR1]dis bgp routing-table 

 BGP Local router ID is 1.1.1.1 
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete

 Total Number of Routes: 5
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>i  4.4.4.4/32         150.1.1.2       0          100        0      200?
 * i                     150.2.2.2       0          100        0      200?
 *>   100.100.100.100/32 0.0.0.0         0                     0      i
 *>i  150.1.1.0/30       2.2.2.2         0          100        0      i
 *>i  150.2.2.0/30       3.3.3.3         0          100        0      i

As you can see in the IP routing table, Loopback0 of router AR4 is available through IBGP, with the next hop 10.1.1.2 (AR2). From BGP routing table you can notice that there are 2 paths to network 4.4.4.4/32. One of them is chosen as the best path by BGP.

Let’s focus on Local Preference attribute. In our case, we can see that both paths have the same local preference value. Now we will change it to let BGP to choose the best path, based on local preference attribute:

[AR2]bgp 100
[AR2-bgp]default local-preference 200

[AR3]bgp 100
[AR3-bgp]default local-preference 300

Let’s check IP and BGP routing tables of AR1 once again:

[AR1]dis ip rout
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
         Destinations : 18       Routes : 19       

Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

        1.1.1.1/32  Direct  0    0           D   127.0.0.1       LoopBack0
        2.2.2.2/32  OSPF    10   1           D   10.1.1.2        GigabitEthernet0/0/0
        3.3.3.3/32  OSPF    10   1           D   10.1.2.2        GigabitEthernet0/0/1
        4.4.4.4/32  IBGP    255  0          RD   150.2.2.2       GigabitEthernet0/0/1
       10.1.1.0/30  Direct  0    0           D   10.1.1.1        GigabitEthernet0/0/0
       10.1.1.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
       10.1.1.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
       10.1.2.0/30  Direct  0    0           D   10.1.2.1        GigabitEthernet0/0/1
       10.1.2.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
       10.1.2.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
       10.1.3.0/30  OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
                    OSPF    10   2           D   10.1.2.2        GigabitEthernet0/0/1
100.100.100.100/32  Direct  0    0           D   127.0.0.1       LoopBack100
      127.0.0.0/8   Direct  0    0           D   127.0.0.1       InLoopBack0
      127.0.0.1/32  Direct  0    0           D   127.0.0.1       InLoopBack0
127.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
      150.1.1.0/30  OSPF    10   2           D   10.1.1.2        GigabitEthernet0/0/0
      150.2.2.0/30  OSPF    10   2           D   10.1.2.2        GigabitEthernet0/0/1
255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0

[AR1]dis bgp rout

 BGP Local router ID is 1.1.1.1 
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete

 Total Number of Routes: 4
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>i  4.4.4.4/32         150.2.2.2       0          300        0      200?
 *>   100.100.100.100/32 0.0.0.0         0                     0      i
 *>i  150.1.1.0/30       150.2.2.2       0          300        0      200?
 *>i  150.2.2.0/30       3.3.3.3         0          300        0      i

We can use tracert command to check how traffic is going:

[AR1]tracert -a 100.100.100.100 4.4.4.4
 traceroute to  4.4.4.4(4.4.4.4), max hops: 30 ,packet length: 40,press CTRL_C to break 
 1 10.1.2.2 110 ms  50 ms  50 ms 
 2 150.2.2.2 190 ms  150 ms  120 ms

It means that AR3 router is a gateway for the whole outgoing traffic leaving AS 100.

Let’s check IP routing table of router AR4:

[AR4]dis ip rout
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
         Destinations : 12       Routes : 12       

Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

        4.4.4.4/32  Direct  0    0           D   127.0.0.1       LoopBack0
100.100.100.100/32  EBGP    255  0           D   150.1.1.1       GigabitEthernet0/0/1
      127.0.0.0/8   Direct  0    0           D   127.0.0.1       InLoopBack0
      127.0.0.1/32  Direct  0    0           D   127.0.0.1       InLoopBack0
127.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
      150.1.1.0/30  Direct  0    0           D   150.1.1.2       GigabitEthernet0/0/1
      150.1.1.2/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
      150.1.1.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/1
      150.2.2.0/30  Direct  0    0           D   150.2.2.2       GigabitEthernet0/0/0
      150.2.2.2/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
      150.2.2.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet0/0/0
255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0

As you can see the whole incoming traffic from AS 200 is going through AR2. So we have proved that BGP local preference attribute is applicable only for traffic leaving AS.

Huawei devices support generic MAC (GMAC) ping and trace on Layer 2 networks. Network administrators can use GMAC ping and trace functions to detect Layer 2 network faults, without configuring CFM.

ping mac mac-address vlan vlan-id [ interface interface-type interface-number | -c count | -s packetsize |-t timeout | -p priority-value ]

GMAC ping works at the same manner like 802.1ag MAC ping. It uses the Loopback Message and Loopback Reply (LBM/LBR) and is similar to ICMP ping function. GMAC ping can be used without configuring the MD (Maintenance Domain), MA (Maintenance Association), or MEP (Maintenance association End Point) on the source device, intermediate device, and destination device, as it is required when using 802.1ag. You only need to enable the GMAC function on the intermediate device. Therefore, GMAC ping is applicable to part of or a whole network without reference to MD, MA, and MEP configurations.

trace mac mac-address vlan vlan-id [ interface interface-type interface-number | -t timeout ] *

GMAC trace works at the same manner like 802.1ag MAC trace and uses Link Trace Message/Reply (LTR/LTM), so its function is similar to “trace route”. But GMAC trace can be implemented without configuring the MD, MA, or MEP on the source device, intermediate device, and the destination device. All the intermediate devices can respond with an LTR. Therefore, GMAC trace is applicable to part of or a whole network without reference to MD, MA, and MEP configurations.

Let’s see how these tools work.

First of all, both features have to be enabled on the source, intermediate and destination devices.

<labnarioSW1>sys
Enter system view, return user view with Ctrl+Z.
[labnarioSW1]ping mac enable
[labnarioSW1]trace mac enable

[labnarioSW1]ping mac 4c1f-cc86-2369 vlan 100
Pinging 4c1f-cc86-2369 with 95 bytes of data: 
Reply from 4c1f-cc86-2369: bytes = 117, time = 290ms
Reply from 4c1f-cc86-2369: bytes = 117, time = 30ms
Reply from 4c1f-cc86-2369: bytes = 117, time = 60ms
Reply from 4c1f-cc86-2369: bytes = 117, time = 50ms
Reply from 4c1f-cc86-2369: bytes = 117, time = 10ms
Packets: Sent = 5, Received = 5, Lost = 0 (0% loss)
Minimum = 10ms, Maximum = 290ms, Average = 88ms

[labnarioSW1]trace mac 4c1f-cced-ed92 vlan 100 interface Ethernet 0/0/1 
Tracing the route to 4c1f-cced-ed92 over a maximum of 255 hops:

Hops   Ingress MAC    Ingress Port    Ingress Action    Relay Action
       Egress MAC     Egress Port     Egress Action
 1     4c1f-cced-ed92 Ethernet0/0/1   IngOK             RlyHit
       --             --                          --
Info: Succeed in tracing the destination address 4c1f-cced-ed92.

GMAC ping and trace are part of Ethernet OAM.