Packet over SONET/SDH

-
Packet Over SONET/SDH :
Many of us use the POS interfaces in the routers .
So here we will have one small technical summary about POS(packet over SONET/SDH)
POS also known as PPP over SONET/SDH . This is scheme which uses PPP encapsulation to map IP datagrams into the SONET/SDH payload .

Why SONET/SDH payload and PPP are used for enacapsulation :
Since SONET/SDH is point to point circuit , PPP is well suited here .

POS layers :
There are three pos layers. They are
1 . Bottom layer : mapping into SONET/SDH
2 . Mid layer - Framing of PPP with HDLC .
3 . Top layer – IP encapsulation into PPP
Here I rememember Sridhar G , my mentor in HCL . I created the stream for POS interface and traffic was not success . At that time , he told me to select the HDLC in Agilent RT.
For Ethernet , We use some other encapsulation in RT. Please share that info if u know.

Operation of POS is :


When transmitting : IP -> PPP->FCS generation->Byte stuffing->scrambling-SONET/SDH framing
When receiving : SONET/SDH deframing->descrambling->de stuffing->FCS detection->PPP->IP


Bit stuffing :


In PPP , packet begins and ends with 01111110 .when ever sender sees five consecutives 1s , it automatically inserts the 0 before transmitting . This is stuffing
When ever receiver five consecutive 1s followed by 0 , it destuffs the 0

The main components :

Flag – delimiter of the Frame
Address – Address in PPP packet
Protocol – identifies the network layer protocol
FCS – frame check sequence
Control – Control information in PPP

Comments

Post a Comment

Popular posts from this blog

URL FILTERING IN FORTIGATE

-
Image
URL Filtering in PALO ALTO requires configuration of below things,  1 . Interface/Zone configuration  2 . Static route Configuration .  3 . URL Filtering Configuration  4 . Security Policy Configuration  Topology : Interface , Router Config: 1 . Configure the interface which is connected to linux vm in private network and mgmt interface config system interface     edit "port1"         set ip 10.10.9.11 255.255.255.0         set allowaccess ping https ssh http fgfm     next     edit "port2"         set ip 15.15.15.102 255.255.255.0         set allowaccess ping https ssh http     next end 2 . Configure the interface which is connected to internet config system interface     edit "port3"       ...
Read more

URL FILTERING IN PALO ALTO FIREWALL

-
Image
URL Filtering in PALO ALTO requires configuration of below things,  1 . Interface/Zone configuration  2 . Static route Configuration .  3 . NAT Configuration  4 . URL Filtering Configuration  5 . Security Policy Configuration  Topology : Interface , Router Config: 1 . Configure the interface which is connected to linux vm in private network and mgmt interface config system interface     edit "port1"         set ip 10.10.9.11 255.255.255.0         set allowaccess ping https ssh http fgfm     next     edit "port2"         set ip 15.15.15.102 255.255.255.0         set allowaccess ping https ssh http     next     edit "port3"         set ip 10.48.110.206 255.255.255.0     ...
Read more

Fragmentation and GRE tunnels

-
Image
Fragmentation and GRE tunnels : =================================== What is Tunnel : A tunnel is logical interface that provides a way to encapsulate passenger packet inside a transport protocol. Tunneling has three memory components . 1 . Passenger protocol (Apple talk , CLNS,IP or IPX,DECNET) 2 . Carrier protocol – one of the encapsulation protocols GRE ,IP in IP tunnels 3. Transport protocol – The protocol used to carry the encapsulated protocol Original Packet : IP-TCP-Telnet Tunnel Encapsulated packet : IP-GRE-Original packet Where IP is transport protocol , GRE is the encapsulation protocol , IP is passenger protocol Example : Where IP and DECNET are passenger protocols and GRE is carrier protocol. Why tunnelling is required here ? Two non IP discontiguous networks are separated by IP network. The administrator may not want to connect them together by configuring DECNET in the IP ne...
Read more