4 ms·
An MPLS router would like to know if the encapsulated packet is IPv4 or IPv6. If it is, the packet can be safely put onto multiple links which have the same app
by bryogenic 10y ago
An MPLS router would like to know if the encapsulated packet is IPv4 or IPv6. If it is, the packet can be safely put onto multiple links which have the same approximate costs. They look at the first byte because in IP that is where the version number is stored[1]. Because this assumption may not be true, MPLS can carry Ethernet traffic for example, some times non IP traffic can match. Additionally, until recently, there were no MAC addresses which started with 4 or 6.
[1] https://en.wikipedia.org/wiki/IPv4#Version https://en.wikipedia.org/wiki/IPv4#Version
- revelation 10y agoYo dawg, I heard you like Ethernet, so I put an Ethernet frame into your Ethernet frame? Where is this going? Who is trying to turn LAN into WAN and why?
- bryogenic 10y ago[MPLS is] ... often referred to as a layer 2.5 protocol. It was designed to provide a unified data-carrying service for both circuit-based clients and packet-switching clients which provide a datagram service model. It can be used to carry many different kinds of traffic, including IP packets, as well as native ATM, SONET, and Ethernet frames. https://en.wikipedia.org/wiki/Multiprotocol_Label_Switching https://en.wikipedia.org/wiki/Multiprotocol_Label_Switching
- revelation 10y agoSure, but what's the application for Ethernet in there? I must come across as dense but Ethernet > MPLS > Ethernet feels like a "let's start over" moment.
- dogecoinbase 10y agoVPLS is the standard use case for this scenario.
- beachstartup 10y agoit's to offer normal ethernet service in buildings that are connected through some other kind of metro network. in other words, it's cheaper than making your customer buy a bunch of weird proprietary network equipment to hook up their office wifi.
- jlgaddis 10y agoPeople want layer 2 connectivity between independent networks for a bunch of different reasons. Look into what's driving VXLAN adoption, for example.
- colanderman 10y agoEthernet over IP is a thing too. Useful for bridging networks over a layer 3 link that you may be forced into for whatever reason.