| GGP, Gateway to Gateway Protocol |
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Description | Glossary | RFCs | Publications | Obsolete RFCs |
| Protocol suite: | TCP/IP. |
| Protocol type: | Transport layer routing protocol. |
| Multicast addresses: | |
| IP protocol: | 3. |
| Ports: | |
| URI: | |
| MIME subtype: | |
| SNMP MIBs: | |
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| Links: |
This protocol was used mainly for routing datagrams and other gateway tasks.
GGP is an obsolete protocol and SHOULD NOT be implemented.
The IP protocol is used for host-to-host datagram service in a system of interconnected networks called the Catenet. The network connecting devices are called Gateways. These gateways communicate between themselves for control purposes via a Gateway to Gateway Protocol (GGP). Occasionally a gateway or destination host will communicate with a source host, for example, to report an error in datagram processing. For such purposes ICMP is used.
RFC 1009, pages 22 and 23:
GGP was designed and implemented by BBN for the first experimental Internet gateways. It is still in use in the BBN LSI/11 gateways, but is regarded as having serious drawbacks. GGP is based upon an algorithm used in the early ARPANET IMPs and later replaced by SPF.
GGP is a "min-hop" algorithm, i.e., its length measure is simply the number of network hops between gateway pairs. It implements a distributed shortest-path algorithm, which requires global convergence of the routing tables after a change in topology or connectivity. Each gateway sends a GGP routing update only to its neighbors, but each update includes an entry for every known network, where each entry contains the hop count from the gateway sending the update.
| MAC header | IP header | GGP packet |
GGP packet:
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gateway type | unused | Sequence number | |||||||||||||||||||||||||||||
| GGP message ::: | |||||||||||||||||||||||||||||||
Gateway type.
8 bits.
Specifies the format of the GGP message.
| Type | Description |
|---|---|
| 0 | Echo reply. |
| 2 | Acknowledgment. |
| 8 | Echo request. |
| 9 | Network interface status. |
| 10 | Negative acknowledgment. |
| 12 | Routing update. |
unused.
8 bits.
Must be cleared to zero.
Sequence number. 16 bits.
GGP message. Variable length.
RFCs:
[RFC 778] DCNET Internet Clock Service.
[RFC 792] INTERNET CONTROL MESSAGE PROTOCOL.
[RFC 823] THE DARPA INTERNET GATEWAY.
[RFC 1812] Requirements for IP Version 4 Routers.
[IEN 109] HOW TO BUILD A GATEWAY.
[RFC 1009] Requirements for Internet Gateways.
[RFC 1716] Towards Requirements for IP Routers.
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Description | Glossary | RFCs | Publications | Obsolete RFCs |