Dear,
I am trying to set-up an MLPPP sessie with an MTU higher than 1500 but without fragmentation. The link between PE and CPE supports MTU upto 1530
Concrete situation in testlab is as following
Cisco 7200 with NPE-400 acting as BRAS connected to an Cisco 2900 on his FastEthernet0/1
MTU size on the FastEthernet0/1 is 1530
MTU size on the Gig0/0 of the 2900 is 1530 as well
PE Config
interface FastEthernet0/1
mtu 1530
no ip address
speed auto
duplex auto
pppoe enable group radius-1
no cdp enable
end
bba-group pppoe radius-1
virtual-template 2
tag ppp-max-payload minimum 1492 maximum 1600
interface Virtual-Template2
mtu 1510
ip unnumbered FastEthernet0/0
peer default ip address pool default
keepalive 20
ppp mtu adaptive
ppp lcp echo mru verify
ppp authentication pap radius-1
ppp authorization radius-1
ppp accounting radius-1
ppp multilink
ppp multilink fragment disable
ppp multilink mrru local 1510
CPE Config
interface GigabitEthernet0/0
mtu 1530
no ip address
duplex auto
speed auto
pppoe enable
pppoe-client dial-pool-number 1
end
interface Dialer0
mtu 1510
ip address negotiated
ip virtual-reassembly
encapsulation ppp
dialer pool 1
dialer-group 1
ppp authentication pap callin
ppp pap sent-username ********* password 0 ***************
ppp multilink
ppp multilink fragment disable
ppp multilink mrru local 1510
!
The session comes online and I am seeing an MTU of 1510 on both sides (CPE and PE)
PE
Virtual-Access4 is up, line protocol is up
Hardware is Virtual Access interface
Interface is unnumbered. Using address of FastEthernet0/0 (188.118.4.252)
MTU 1510 bytes, BW 200000 Kbit/sec, DLY 100000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, LCP Open, multilink Open
Open: IPCP
MLP Bundle vaccess, cloned from Virtual-Template2
Vaccess status 0x44, loopback not set
Keepalive set (20 sec)
DTR is pulsed for 5 seconds on reset
Last input 00:00:08, output never, output hang never
Last clearing of "show interface" counters 00:00:45
Input queue: 0/75/0/0 (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
15 packets input, 9568 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
15 packets output, 9982 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
CPE
Virtual-Access4 is up, line protocol is up
Hardware is Virtual Access interface
MTU 1510 bytes, BW 112 Kbit/sec, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, LCP Open, multilink Open
Stopped: CDPCP
Open: IPCP
MLP Bundle vaccess, cloned from Dialer0
Vaccess status 0x44, loopback not set
Keepalive set (10 sec)
DTR is pulsed for 5 seconds on reset
Interface is bound to Di0 (Encapsulation PPP)
Last input 00:00:14, output never, output hang never
Last clearing of "show interface" counters 00:00:53
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/16 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 84 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
16 packets input, 9616 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
16 packets output, 10054 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
So far so good, however, I am not able to transport any packet bigger then 1500 with DF-Flag enabled
yourname#ping 188.118.4.252 size 1500 df-bit
Type escape sequence to abort.
Sending 5, 1500-byte ICMP Echos to 188.118.4.252, timeout is 2 seconds:
Packet sent with the DF bit set
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
yourname#ping 188.118.4.252 size 1501 df-bit
Type escape sequence to abort.
Sending 5, 1501-byte ICMP Echos to 188.118.4.252, timeout is 2 seconds:
Packet sent with the DF bit set
.....
Success rate is 0 percent (0/5)
yourname#
Any ideas?
