peering-toolbox:route_server
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peering-toolbox:route_server [2022/07/31 21:28] – [Implementations] philip | peering-toolbox:route_server [2022/08/01 16:26] – [Purpose] philip | ||
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Without a Route Server, the BGP mesh at an IXP would look similar to the following diagram: | Without a Route Server, the BGP mesh at an IXP would look similar to the following diagram: | ||
- | {{: | + | {{: |
- | basically an n-squared mesh. | + | where each line represents a BGP session between two IXP members. This is basically an n-squared mesh. |
Introducing a Route Server results in the BGP sessions for each member being with the Route Route Server, meaning that the number of BGP sessions goes up linearly per member (from Route Server point of view). | Introducing a Route Server results in the BGP sessions for each member being with the Route Route Server, meaning that the number of BGP sessions goes up linearly per member (from Route Server point of view). | ||
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It is important to note that the Route Server is not involved in packet forwarding at the IXP, nor does it carry any of the IXP's traffic. The Route Server takes advantage of a BGP feature known as "third party next-hop" | It is important to note that the Route Server is not involved in packet forwarding at the IXP, nor does it carry any of the IXP's traffic. The Route Server takes advantage of a BGP feature known as "third party next-hop" | ||
- | The Route Server also does not insert its Autonomous System Number into the AS Path. This means that, to all intents and purposes, it appears as though the IXP members are peering directly with each other, as their AS Numbers appear immediately adjacent in the AS Path. BGP implementations adhering to the BGP specification as per RFC4271 will need to disable the AS adjacency check for any session with a Route Server - BGP requires that the peer AS must be the first AS in the AS_PATH, something that a Route Server does not do. | + | The Route Server also does not insert its Autonomous System Number into the AS Path. This means that, to all intents and purposes, it appears as though the IXP members are peering directly with each other, as their AS Numbers appear immediately adjacent in the AS Path. BGP implementations adhering to the BGP specification as per [[https:// |
On Cisco IOS, for example, the configuration commands to do this are: | On Cisco IOS, for example, the configuration commands to do this are: |
peering-toolbox/route_server.txt · Last modified: 2022/08/26 20:04 by philip