Cisco Router 2600 Serial Port communications

sebahelder · ‎05-14-2014

I am working on configuring communications Router to Router through serial port. I have seen some videos and read some documentations. My configuration is as follows:

R1 (DCE) -> f0/0 192.168.1.1/24 - s0/0 192.168.2.1/24 <-----> Router2 ->(DTE) S0/1 192.168.2.2/24 f0/0 192.168.3.1.

I have configured the routing tables at both routers. It works when I ping from router to router and router to hosts successfully. Nevertheless, I can ping from hosts to the default gateways, but I cannot ping from hosts to the serial ports (adjacency). In short I cannot communicate from Network1 to Network2. Please do I have to do any extra configuration.

SANTHOSHKUMAR SARAVANAN · ‎05-14-2014

Hi ,

Reverse routing is missing on your peer router /both router . when you ping from router you must be pinging because your router takes your serial interface as your source interface . But when you ping from PC host the source interface is fa0/0 , though peer router dont have route back you are unable to ping .

config static routing

on R1

ip route 192.168.3.0 255.255.255.0 192.168.2.2

on R2

ip route 192.168.1.0 255.255.255.0 192.168.2.1

after configuring this you should able to ping from both side host machine .

HTH

Sandy

Do rate for the post if your question is answered .

sebahelder · ‎05-14-2014

Adding more information to give a better view:

Router 1 ip route:

C 192.168.1.0/24 is directly connected, Ethernet0/0
S 192.168.2.0/24 [1/0] via 192.168.3.2
C 192.168.3.0/24 is directly connected, Serial0/0

=================================================

Router 2 ip route:

S 192.168.1.0/24 [1/0] via 192.168.3.1
C 192.168.2.0/24 is directly connected, Ethernet0/0
C 192.168.3.0/24 is directly connected, Serial0/1

=================================================

From any router I can ping any of the hosts.

From the host 1 I just can ping f0/0 on router 1. I cannot ping s0/0 on router 1.

From host 2 I just can ping f0/0 on router 2. I cannot ping s0/1 on router 2.

Thus I cannot reach host 2 from host 1. Any help is very much appreciated.

SANTHOSHKUMAR SARAVANAN · ‎05-14-2014

Hi ,

Your show output result command is different from your representation , Can you share me your router configuration of both routers

R1 (DCE) -> f0/0 192.168.1.1/24 - s0/0 1~~92.168.2.1/24~~ <-----> Router2 ->(DTE) S0/1 ~~192.168.2.2/24~~ f0/0 192.168.3.1.

Based on that i can fix your problem .

HTH

Sandy

sebahelder · ‎05-14-2014

Yes, my representation should be like this:

R1 (DCE) -> f0/0 192.168.1.1/24 - s0/0 192.168.2.1/24 <-----> Router2 ->(DTE) S0/0 192.168.3.2/24 f0/0 192.168.2.1.

As for the rest, the configuration is the same. I cannot ping from any host to the adjacency though.

SANTHOSHKUMAR SARAVANAN · ‎05-14-2014

Hi ,

Look into attached PPT file for disabling autoconfig , connect your serial cable after confguring your serial interface .

Router 2 (HelderR)

HelderR#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Serial0/0 192.168.3.2 YES SLARP up up

Basically when the router reloaded, it is then sending DHCP discover packets looking for DHCP server. If no DHCP server available, it will look for BOOTP server. The next thing if it can’t find BOOTP server, it will send RARP and SLARP.

http://www.davidsudjiman.info/2007/01/07/serial-line-address-resolution-protocol-slarp/

The router will also send out Reverse Address Resolution Protocol (RARP) and Serial Line Address Resolution Protocol (SLARP) requests. AutoInstall will use the first available method (DHCP, BOOTP, RARP, or SLARP) for configuration. If all LAN interface configuration options fail, AutoInstall will attempt to configure an available serial interface using SLARP. Though DHCP is the preferred method for AutoInstall over LAN interfaces, these other options remain enabled to ensure backward compatibility with older network topologies.

Serial Line Address Resolution Protocol

Serial Line ARP (SLARP) is used for serial interfaces that use High-Level Data Link Control (HDLC) encapsulation. A SLARP server, intermediate (staging) router, and another router providing a SLARP service may be required in addition to a TFTP server. If an interface is not directly connected to a server, the staging router is required to forward the address resolution requests to the server, otherwise a directly connected router with SLARP service is required. The Cisco IOS XE software attempts to use SLARP if it does not know the IP address of an interface at startup to respond to SLARP requests that software is able to answer.

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_arp/configuration/xe-3s/asr1000/arp-xe-3s-asr1000-book/arp-config-arp.html

HTH

Sandy.

sebahelder · ‎05-14-2014

Router 1 (KelliR)

KelliR#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 192.168.1.1 YES manual up up
Serial0/0 192.168.3.1 YES manual up up
TokenRing0/0 unassigned YES unset administratively down down
Serial0/1 unassigned YES unset administratively down down
KelliR#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

C 192.168.1.0/24 is directly connected, Ethernet0/0
S 192.168.2.0/24 [1/0] via 192.168.3.2
C 192.168.3.0/24 is directly connected, Serial0/0
============================================

Router 2 (HelderR)

HelderR#
HelderR#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 192.168.2.1 YES manual up up
Serial0/0 192.168.3.2 YES SLARP up up
TokenRing0/0 unassigned YES unset administratively down down
Serial0/1 unassigned YES unset administratively down down
HelderR#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

S 192.168.1.0/24 [1/0] via 192.168.3.1
C 192.168.2.0/24 is directly connected, Ethernet0/0
C 192.168.3.0/24 is directly connected, Serial0/0

============================================

Even with f0/0 and s0/0 configured with the addresses in any router, no host at its respective routers is able to ping the s0/0. Hosts are able to ping its ethernet ports.

See ping comand below:

From router KelliR

KelliR#ping 192.168.3.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/33/36 ms
KelliR#ping 192.168.2.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/34/36 ms
KelliR#ping 192.168.2.101

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.101, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/33/36 ms
KelliR#

==================================================================================

From router HelderR

HelderR#ping 192.168.3.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/33/36 ms
HelderR#ping 192.168.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/32 ms
HelderR#ping 192.168.1.101

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.101, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/34/36 ms
HelderR#

====================================================

From Host connected to KelliR

C:\>ping 192.168.1.1

Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.1: bytes=32 time=2ms TTL=255
Reply from 192.168.1.1: bytes=32 time=1ms TTL=255
Reply from 192.168.1.1: bytes=32 time=1ms TTL=255
Reply from 192.168.1.1: bytes=32 time=1ms TTL=255

Ping statistics for 192.168.1.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 2ms, Average = 1ms

C:\>ping 192.168.3.1

Pinging 192.168.3.1 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 192.168.3.1:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss)

=====================================================

From Host connected to HelderR

C:\Users\Helder>ping 192.168.2.1

Pinging 192.168.2.1 with 32 bytes of data:

Reply from 192.168.2.1: bytes=32 time=3ms TTL=255

Reply from 192.168.2.1: bytes=32 time=1ms TTL=255

Ping statistics for 192.168.2.1:

Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 1ms, Maximum = 3ms, Average = 1ms

C:\Users\Helder>ping 192.168.3.2

Pinging 192.168.3.2 with 32 bytes of data:

Request timed out.

Ping statistics for 192.168.3.2:

Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),