Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 112)

IPv4 GRE tunnel overview
Generic Routing Encapsulation is described in RFC 2784. Generally, GRE provides a way to
encapsulate arbitrary packets (payload packet) inside of a transport protocol, and transmit them from
one tunnel endpoint to another. The payload is encapsulated in a GRE packet. The resulting GRE
packet is then encapsulated in a delivery protocol, then forwarded to the tunnel destination. At the
tunnel destination, the packet is decapsulated to reveal the payload. The payload is then forwarded to
its final destination.
Brocade devices allow the tunneling of packets of the following protocols over an IPv4 network using
GRE:
• OSPF V2
• BGP4
• RIP V1 and V2
NOTE
This is not supported on ICX 6450 devices.
GRE packet structure and header format
FIGURE 14 GRE encapsulated packet structure
IPv4 GRE tunnel overview
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