To verify the MTU sizes for an interface, use the show interfaces, show ip interface, and show mpls interface commands, as in the following examples:
 Note |
The output of the show interfaces atm command can display configuration of AAL5 encapsulation, but only AAL0 is supported on the Cisco ASR 1000 Series Aggregation Services Routers.
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Router# show interfaces atm 0/2/2
ATM0/2/2 is up, line protocol is up
Hardware is SPA-3XOC3-ATM-V2, address is 001a.3044.7522 (bia 001a.3044.7522)
MTU 4470 bytes, sub MTU 4470, BW 149760 Kbit, DLY 80 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ATM, loopback not set
Keepalive not supported
Encapsulation(s): AAL5 AAL0
4095 maximum active VCs, 1 current VCCs
VC Auto Creation Disabled.
VC idle disconnect time: 300 seconds
4 carrier transitions
Last input never, output 00:04:11, output hang never
Last clearing of "show interface" counters never
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
5 packets input, 540 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
5 packets output, 540 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 output buffer failures, 0 output buffers swapped out
Router# show ip interface atm 0/2/2.1
ATM0/2/2.1 is up, line protocol is up
Internet address is 10.4.0.2/24
Broadcast address is 255.255.255.255
Address determined by setup command
MTU is 4470 bytes
Helper address is not set
Directed broadcast forwarding is disabled
Outgoing access list is not set
Inbound access list is not set
Proxy ARP is enabled
Local Proxy ARP is disabled
Security level is default
Split horizon is disabled
ICMP redirects are always sent
ICMP unreachables are always sent
ICMP mask replies are never sent
IP fast switching is enabled
IP Flow switching is disabled
IP CEF switching is enabled
IP Distributed switching is disabled
IP CEF switching turbo vector
IP Null turbo vector
Associated unicast routing topologies:
Topology "base", operation state is UP
IP multicast fast switching is enabled
IP multicast distributed fast switching is disabled
IP route-cache flags are Fast, CEF
Router Discovery is disabled
IP output packet accounting is disabled
IP access violation accounting is disabled
TCP/IP header compression is disabled
RTP/IP header compression is disabled
Probe proxy name replies are disabled
Policy routing is disabled
Network address translation is disabled
BGP Policy Mapping is disabled
Input features: MCI Check
WCCP Redirect outbound is disabled
WCCP Redirect inbound is disabled
WCCP Redirect exclude is disabled
Router# show mpls interface atm 0/3/2.1
Interface IP Tunnel BGP Static Operational
ATM0/3/2.1 Yes (ldp) No No No Yes
CE1#sh mpls int atm0/3/2.1 det
Interface ATM0/3/2.1:
IP labeling enabled (ldp):
Interface config
LSP Tunnel labeling not enabled
BGP labeling not enabled
MPLS operational
MTU = 4470
To view the maximum possible size for datagrams passing out the interface using the configured MTU value, use the show atm interface atm command:
Router# show atm interface atm 0/2/2
Interface ATM0/2/2:
AAL enabled: AAL0, Maximum VCs: 4095, Current VCCs: 1
Max. Datagram Size: 4528
PLIM Type: SONET - 155000Kbps, TX clocking: LINE
Cell-payload scrambling: ON
sts-stream scrambling: ON
5 input, 5 output, 0 IN fast, 0 OUT fast, 0 out drop
Avail bw = 149760
Config. is ACTIVE