From: Asim Khan (asimmegawatt@xxxxxxxxx)
Date: Wed Aug 07 2002 - 05:08:43 GMT-3
Hi Brian
You are right that IPCP must be open before IP will
work. I just did what you mentioned. I first
configured the encap on both the interfaces (router1
and router2), the "show int s0" showed up/up. After
that I configured the addresses on both the interfaces
and then I initiated the ping from R2 to R1. Initially
the ping didn't work but after sometimes when IPCP had
been negotiated, the ping work. I didn't shutdown the
interfaces and bring them back nor did I reboot the
router. Please see the config
Router2(config)#int s0
Router2(config-if)#encap
Router2(config-if)#encapsulation ppp
Router2(config-if)#no shut
Router2(config-if)#^Z
Router2# sh int s0
Serial0 is up, line protocol is up
Hardware is HD64570
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely
255/255, load 1/255
Encapsulation PPP, loopback not set, keepalive set
(10 sec)
LCP Open
Open: CDPCP
Router1#sh int s0
Serial0 is up, line protocol is up
Hardware is HD64570
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely
255/255, load 1/255
Encapsulation PPP, loopback not set, keepalive set
(10 sec)
LCP Open
Open: CDPCP
Last input 00:00:01, output 00:00:01, output hang
never
Router1#conf t
Enter configuration commands, one per line. End with
CNTL/Z.
Router1(config)#int s0
Router1(config-if)#ip address 200.20.1.129
255.255.255.240
Router1(config-if)#^Z
Router2#conf t
Enter configuration commands, one per line. End with
CNTL/Z.
Router2(config)#int s0
Router2(config-if)#ip address 200.20.1.130
255.255.255.224
Router2(config-if)#^Z
Router2#
Router2#ping 200.20.1.129
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 200.20.1.129,
timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Router2#sh int s0
Serial0 is up, line protocol is up
Hardware is HD64570
Internet address is 200.20.1.130/27
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely
255/255, load 1/255
Encapsulation PPP, loopback not set, keepalive set
(10 sec)
LCP Open
Listen: IPCP <----------- IPCP negotiation
Open: CDPCP
Router1#sh int s0
Serial0 is up, line protocol is up
Hardware is HD64570
Internet address is 200.20.1.129/28
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely
255/255, load 1/255
Encapsulation PPP, loopback not set, keepalive set
(10 sec)
LCP Open
Open: CDPCP
Router1#sh ip route
Gateway of last resort is not set
200.20.1.0/28 is subnetted, 1 subnets
C 200.20.1.128 is directly connected, Serial0
Router1#ping 200.20.1.130
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 200.20.1.130,
timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip
min/avg/max = 32/32/32 ms
Router1#ping 200.20.1.130
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 200.20.1.130,
timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip
min/avg/max = 32/34/36 ms
Router1#sh ip route
Gateway of last resort is not set
200.20.1.0/24 is variably subnetted, 2 subnets, 2
masks
C 200.20.1.128/28 is directly connected, Serial0
C 200.20.1.130/32 is directly connected, Serial0
Router1#sh ip route
Gateway of last resort is not set
200.20.1.0/24 is variably subnetted, 2 subnets, 2
masks
C 200.20.1.128/28 is directly connected, Serial0
C 200.20.1.130/32 is directly connected, Serial0
Router2#ping 200.20.1.129
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 200.20.1.129,
timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip
min/avg/max = 36/39/52 ms
Router2#sh ip route
Gateway of last resort is not set
200.20.1.0/24 is variably subnetted, 2 subnets, 2
masks
C 200.20.1.129/32 is directly connected, Serial0
C 200.20.1.128/27 is directly connected, Serial0
Router2#ping 200.20.1.129
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 200.20.1.129,
timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip
min/avg/max = 32/32/32 ms
Router2#
--- Brian Dennis <brian@5g.net> wrote:
> There must be another issue causing your problem
> because having the
> subnet mask different will not stop them from
> pinging each other in this
> case.
>
> One thing to remember about PPP is even if the line
> is UP/UP it doesn't
> mean that IP with flow across it. You must have IPCP
> (IP Control
> Protocol) open before IP will work. If an interface
> with PPP
> encapsulation is UP/UP but doesn't have an IP
> address configured when
> the interface was first brought up, IPCP will not be
> negotiated. This
> means that if you add an IP address to each side
> they will not be able
> to ping each other until the interface is brought
> down and then back up
> so IPCP can be negotiated and go into the open
> state.
>
> Brian Dennis, CCIE #2210 (R&S/ISP Dial)
>
> -----Original Message-----
> From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> Sam Dagoski
> Sent: Tuesday, August 06, 2002 7:49 PM
> To: Asim Khan; ccielab@groupstudy.com
> Subject: Re: Funny Serial problem
>
> Yea, but it does not work. I think PPP must
> exchange
> network layer information.
>
> Thanks everyone for all of your help!
>
>
> --- Original Message ---
> From: Asim Khan <asimmegawatt@yahoo.com>
> To: Sam Dagoski <DAGOMEISTER@prodigy.net>,
> ccielab@groupstudy.com
> Subject: Re: Funny Serial problem
>
> >Given your configuration, both routers will ping
> each
> >other despite different netwrok masks. The reason
> is
> >after ANDing the addresses with the netmasks, they
> are
> >on the same subnet i.e 200.20.1.128
> >
> >However if both addresses fall in different subnets
> >then they can't ping each other.
> >
> >Regards.
> >
> >Asim Khan
> >
> >
> >
> >--- Sam Dagoski <DAGOMEISTER@prodigy.net> wrote:
> >> How come this does not work:
> >>
> >> Router 1:
> >> inter s0
> >> ip address 200.20.1.129 255.255.255.240
> >> encap ppp
> >>
> >> Router 2:
> >> inter s0
> >> ip address 200.20.1.130 255.255.255.224
> >> encap ppp
> >>
> >> The masks are different. If the masks are
> different
> >>
> >> on a serial connection, the two sides will not be
>
> >> able to ping each other -- even thought the line
> is
> >> up and line protocol is up.
> >>
> >> Any ideas?
> >>
> >>
>
>-----------------------------------------------------
> ----
> >> Sam Dagoski
> >> Priciple Engineer
> >>
>
This archive was generated by hypermail 2.1.4 : Sat Sep 07 2002 - 19:48:18 GMT-3