Sunday, November 15, 2009

PPP CCNA Review and Lab


Even though I'm only working on about 4 hours of sleep (out way to late last night) I managed to get through the rather simple PPP Chapter in the Cisco ICND2 book. The lab that the Cisco press book provides was rather simple and I decided to come up with my own real world scenario based on some of the WAN setups at my job. A lot of circuits actually use what's called a multilink which basically allows you to load-balance a WAN connection over multiple serial interfaces. I never setup a multilink before but seen it plenty of times when I have referenced running configs on routers. I decided to give this a whirl and ran into a few hiccups but managed to get everything running smoothly with one caveat. I never could get the RIP protocol to work across it for one reason or another, I believe it was due to using a classful network address on both routers. Even with the no auto-summary command I was still unable to get the two routers to exchange RIP info about their 172.16.0.0 /16 networks. I simply used OSPF and sure enough everything came right up, even though I misconfigured my multilink setup at first as well. When setting up a PPP multilink you don't put an IP address on the actual serial interfaces. Instead you create a virtual interface called multilinknumber in which you apply the ip address. You also need to add all the serial interfaces along with the multilink interface into what's called a multilink group. Once this is setup you should be ready to go, I've included what one of the router running configs looks like below:

I highlighted things of importance
R0#sh run
Building configuration...

Current configuration : 14
!
version 12.4
service timestamps debug d
service timestamps log dat
service password-encryptio
!
hostname R0
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$vn1e$JT
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
no ip domain lookup
ip auth-proxy max-nodata-c
ip admission max-nodata-co
!
multilink bundle-name auth
!

username R1 password 7 001
archive
log config
hidekeys
!
!
!
interface Loopback0
ip address 172.16.2.1 255
!
interface Multilink1
ip address 192.168.124.1
ppp authentication chap
ppp multilink
ppp multilink group 1
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial0/0
no ip address
encapsulation ppp
clock rate 64000
ppp authentication chap
ppp multilink
ppp multilink group 1
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface Serial0/1
no ip address
encapsulation ppp
clock rate 64000
ppp authentication chap
ppp multilink
ppp multilink group 1
!
router ospf 1
log-adjacency-changes
network 172.16.0.0 0.0.25
network 192.168.124.0 0.0
!
ip forward-protocol nd
!
!
ip http server
no ip http secure-server
!
!
control-plane
!
!

!
line con 0
exec-timeout 3000 0
password 7 00171E090B490E
login
line aux 0
line vty 0 4
login
!
!
end

No comments:

Post a Comment