--> ATOM architecture is based upon pseudowires.
--> Pseudowires forward layer 2 traffic from one provider edge to another provider edge router over MPLS or IP backbone.
--> Pseudowires emulates as a wire or a tunnel that carries layer 2 frames.
--> The link between PE and CE router is called as Attachment Circuit and it can be ATM,frame-relay, HDLC, PPP, and so on.
--> The ingress pe router receives layer 2 frames, it encapsulates the frames and sends them to egress pe router.
--> Egress PE router decapsulates the frames which are received and sends them to customer edge router.
--> If CE routers are running CDP, they can see each other as directly connected neighbors.
--> CE routers can form any routing protocol adjacency as they are seen as directly connected at Layer2.
--> In ATOM, PE routers should run targeted LDP session between them. An Ingress PE router receives the frame from CE router and forwards the frame across MPLS backbone to Egress PE router with two labels: VC Label and Tunnel Label.
--> Tunnel Label is used to Identify Egress PE router across MPLS backbone and VC Label ( bottom) is used to identify the customer router which is connected to Egress PE router.
Md.Kareem
CCIE # 54759
Ref: Cisco.com
--> Pseudowires forward layer 2 traffic from one provider edge to another provider edge router over MPLS or IP backbone.
--> Pseudowires emulates as a wire or a tunnel that carries layer 2 frames.
--> The link between PE and CE router is called as Attachment Circuit and it can be ATM,frame-relay, HDLC, PPP, and so on.
--> Egress PE router decapsulates the frames which are received and sends them to customer edge router.
--> If CE routers are running CDP, they can see each other as directly connected neighbors.
--> CE routers can form any routing protocol adjacency as they are seen as directly connected at Layer2.
--> In ATOM, PE routers should run targeted LDP session between them. An Ingress PE router receives the frame from CE router and forwards the frame across MPLS backbone to Egress PE router with two labels: VC Label and Tunnel Label.
--> Tunnel Label is used to Identify Egress PE router across MPLS backbone and VC Label ( bottom) is used to identify the customer router which is connected to Egress PE router.
Md.Kareem
CCIE # 54759
Ref: Cisco.com
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