Thursday, February 6, 2014

NTS: PPP/Serial/POS

PPP/Serial/POS




PPP (Point-to-Point Protocol) is defined in RFC 1661.
PPPoE (PPP over Ethernet) is described in RFC 2516.



Serial

Don't forget to to set the clock rate (i.e. 64000) on the DCE interface (usually the one on the service provider router).



PPP

You can use "no peer neighbor route" in order to disable creating a /32 for the peer address.




Multilink PPP

R1 (IOS)
interface Serial2/0
 encapsulation ppp
 ppp multilink
 ppp multilink group 1
 clock rate 64000
!

interface Multilink1
 ip address 12.12.12.1 255.255.255.0
 ppp multilink
 ppp multilink group 1



R2 (IOS)
interface Serial0/0
 encapsulation ppp
 ppp multilink
 ppp multilink group 1

!
interface Multilink1
 ip address 12.12.12.2 255.255.255.0
 ppp multilink
 ppp multilink group 1





Multichassis Multilink PPP

SGBP is used between routers to coordinate them for multilink ppp termination.

R4 (IOS)
sgbp group SGBP-GRP
sgbp member R5 5.5.5.5
sgbp source-ip 4.4.4.4

!
username SGBP-GRP password 0 SGBP-PASS

!
multilink virtual-template 1
!
interface Virtual-Template1
 ip unnumbered Loopback0
 ppp multilink
 


R5 (IOS)
sgbp group SGBP-GRP
sgbp member R4 4.4.4.4
sgbp source-ip 5.5.5.5
username SGBP-GRP password 0 SGBP-PASS

!
multilink virtual-template 1
!
interface Virtual-Template1
 ip unnumbered Loopback0
 ppp multilink



IOS
R4#sh sgbp
Group Name: SGBP-GRP Ref: 0xDE80000
Seed bid: default, 50, default seed bid setting

  Member Name: R5 State: active Id: 1
  Ref: 0xABC0000
  Address: 5.5.5.5
  Other Active Address: 20.4.5.5





PPPoE

IOS

PPPoE server
bba-group pppoe global
 virtual-template 1
!
interface Virtual-Template1
 mtu 1492
 ip address 10.10.10.1 255.255.255.0

!
interface X
 pppoe enable group global


PPPoE client
interface X
 pppoe enable
 pppoe-client dial-pool-number 1
!
interface Dialer1
 mtu 1492
 ip address 10.10.10.2 255.255.255.0
 encapsulation ppp

 dialer pool 1

Interface X is assumed to be an ethernet interface.

You must define "encapsulation ppp" under the dialer, otherwise the ppp call won't happen.

Not all routers support the PPPoE functionality.

PPPoE server/client is not supported on IOS-XR of C12k.



PPP Authentication

IOS

Server
username USERNAME password PASSWORD
!
interface POS2/0
 encapsulation ppp
 ppp authentication chap


Client
interface POS2/0
 encapsulation ppp
 ppp chap hostname USERNAME
 ppp chap password PASSWORD



If you don't define a chap hostname, then the router's name is used as the username.

In the following example the first router authenticates the second using CHAP (encrypted), while the second router authenticates the first using PAP (cleartext).

IOS

Server & Client #1
username R2-USER password R2-PASS
!
interface POS2/0
 encapsulation ppp
 ppp authentication chap
 ppp pap sent-username R1-USER password R1-PASS



Server & Client #2
username R1-USER password R1-PASS
!
interface POS2/0
 encapsulation ppp
 ppp authentication pap

 ppp chap hostname R2-USER
 ppp chap password R2-PASS





POS (Packet over SONET/SDH)
 
POS default MTU is 4470.

MPLS-TE isn't supported on POS frame-relay subinterfaces on C12k running IOS-XR.



POS Configuration

You will find most configurations parameters under the following command:

IOS
R1(config-if)#pos ?
  ais-shut      Send LAIS when shutdown
  delay         Delay POS alarm triggers
  flag          Specify byte value
  framing       specify framing
  report        enable reporting of selected alarms
  scramble-atm  Enable POS SPE scrambling
  threshold     Set BER threshold values



Verification checks can be performed with:

IOS
R1#sh controllers pos2/0
POS2/0
SECTION
  LOF = 0          LOS    = 0                            BIP(B1) = 0
LINE
  AIS = 0          RDI    = 0          FEBE = 0          BIP(B2) = 0
PATH
  AIS = 0          RDI    = 0          FEBE = 0          BIP(B3) = 0
  PLM = 0          UNEQ   = 1          TIM  = 0          TIU     = 0
  LOP = 0          NEWPTR = 0          PSE  = 0          NSE     = 0

Active Defects: PUNEQ
Active Alarms:  None
Alarm reporting enabled for: SF SLOS SLOF B1-TCA B2-TCA PLOP B3-TCA

Framing: SONET
APS

  COAPS = 0          PSBF = 0
  State: PSBF_state = False
  Rx(K1/K2): 00/00  Tx(K1/K2): 00/00
  S1S0 = 00, C2 = 00
  Remote aps status (none); Reflected local aps status (none)
CLOCK RECOVERY
  RDOOL = 0
  State: RDOOL_state = False
PATH TRACE BUFFER: STABLE
  Remote hostname :
  Remote interface:
  Remote IP addr  :
  Remote Rx(K1/K2):   /    Tx(K1/K2):   /

BER thresholds:  SF = 10e-3  SD = 10e-6
TCA thresholds:  B1 = 10e-6  B2 = 10e-6  B3 = 10e-6

  Clock source:  line



Don't expect all things to work in GNS3.



Keepalives

The keepalive command applies to serial interfaces using HDLC or PPP encapsulation. It does not apply to serial interfaces using Frame Relay encapsulation.

Keepalives are independent between the two peers. One peer end can have keepalives enabled; the other end can have them disabled. Even if keepalives are disabled locally, LCP still responds with ECHOREP packets to the ECHOREQ packets it receives.



CRC

The cyclic redundancy check (CRC) on a serial interface defaults to a length of 16 bits. You can change it to 32 bits.


IOS 
interface POS2/0
 crc 32


IOS
R1#sh int pos2/0
POS2/0 is up, line protocol is up
  Hardware is Packet over Sonet
  Internet address is 10.10.10.1/24
  MTU 4470 bytes, BW 155000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation HDLC, crc 32, loopback not set

 




POS Channel

POS channel link bundling provides load-balancing across all active links in a bundle.


IOS
interface pos-channel 1
 ip address 30.30.30.1 255.255.255.0
!
interface pos2/0
 channel-group 1
!
interface pos3/0
 channel-group 1


POS link bundling is supported on very specific hardware.



APS

The APS feature provides redundancy and allows for a switchover of POS circuits in the event of circuit failure.

You configure a pair of SONET/SDH lines for line redundancy. When the Working (W) interface fails, the Protect (P) interface quickly assumes the traffic load (usual swichover time is 50 ms)

Most configuration options are found under the "aps" command:

IOS
R1(config-if)#aps ?
  authentication  Authentication string
  force           Force channel
  group           Group association
  lockout         Lockout protection channel
  manual          Manually switch channel
  protect         Protect specified circuit
  reflector       Configure for reflector mode APS
  revert          Specify revert operation and interval
  signalling      Specify SONET/SDH K1K2 signalling
  timers          APS timers
  unidirectional  Configure for unidirectional mode
  working         Working channel number



Configuration

IOS
interface Loopback0
 ip address 1.1.1.1 255.255.255.255
!
interface POS2/0
 ip address 10.10.10.1 255.255.255.0
 aps group 10
 aps working 1
!

interface POS3/0
 ip address 20.20.20.1 255.255.255.0
 aps group 10
 aps protect 1 1.1.1.1
 aps revert 1


You need the configure a similar setup on the peer router too.

You can have the Working and Protect interfaces on different routers and they will communicate each other using PGP (Protect Group Protocol), which runs over UDP.

IOS
R1#sh aps
POS3/0 APS Group 10: protect channel 0 (Inactive)
        Working channel 1 at 1.1.1.1 (Enabled)
        bidirectional, revertive (60 seconds)
        PGP timers (default): hello time=1; hold time=3
                hello fail revert time=120
        SONET framing; SONET APS signalling by default
        Received K1K2: 0x00 0x00
                No Request (Null)
        Transmitted K1K2: 0x00 0x05
                No Request (Null)
        Remote APS configuration: (null)

POS2/0 APS Group 10: working channel 1 (Active)
        Protect at 1.1.1.1
        PGP timers (from protect): hello time=1; hold time=3
        SONET framing
        Remote APS configuration: (null)


You need an ADM between the routers for the K1/K2 signals to work.



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