#14148 (Custom MTU for PPPoE connection is set for
MX Series. You can configure the maximum transmission unit (MTU) and maximum receive unit for Point-to-Point Protocol (PPP) subscribers. This configuration is supported for the following PPP subscribers: To figure out the MSS you want, you take the standard 1500 MTU and subtract the PPPoE header, the IP header, and the TCP header (20 bytes 3): 1500 - 8 - 20 - 20 = 1452. EdgeRouter If you have an EdgeRouter, you'll want the following configuration options to set the MTU for your PPPoE connection and MSS clamping, where eth0 is the interface you Windows machines from visa on will auto determine the MTU and would match the router setting. @Oldjim For what it's worth: Plusnet TG582n router will by default use a MTU of 1492 when configured for pppoe (fibre). When configured for ADSL it defaults to a MTU of 1500. Don't know about the 2704n. The PPP channel MTU is used with Multilink PPP when ppp_mp_explode() (see ppp_generic module) tries to determine how big a fragment might be. According to RFC 1661, the MTU excludes the 2-byte PPP protocol field, see the corresponding comment and code in ppp_mp_explode(): /* * hdrlen includes the 2-byte PPP protocol field, but the
HOW TO: Change the Default Maximum Transmission Unit (MTU
MTU/MRU When a PPPoE-speaking DSL modem sends or receives Ethernet frames containing PPP + PPPoE payload across the Ethernet link to a router (or PPPoE-speaking single PC), PPP + PPPoE contributes an additional overhead of 8 bytes = 2 (PPP) + 6 (PPPoE) included within the payload of each Ethernet frame. In computer networking, the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction. The MTU relates to, but is not identical to the maximum frame size that can be transported on the data link layer, e.g. Ethernet frame. MTU Issues¶ Issues with upload speed frequently end up being issues with the MTU. If the MTU on pfSense® software (default 1500), is higher than the MTU of the upstream link, it can result in packets being fragmented, lost, or otherwise mishandled. Setting MSS clamping on the WANs or changing the MTU of the interface may help.
I understant that the usual maxium mtu on a PPPoE connection is 1492 (1500 minus the 8 bits that PPPoE is adding). but that said, Bell allows us to use 1500 (1500+8). Some users did this with their own pfsense "router" and this helps to get a little bit more throuput. So why is this EA9500 router limited to 1492 when a PPPoE is used?
i used at as A pppoe server i have used QINQ secend tag in rotuer. interface TenGigabitEthernet2/0/0.904 description Cust1-QINQ encapsulation dot1Q 904 second-dot1q any pppoe enable group PPPOE-SERVER3 interface Virtual-Template2 **mtu 1492** ip unnumbered Loopback0 ip nat inside no logging event link-status peer default ip address pool interface localpool2 keepalive 15 ppp mtu adaptive ppp May 09, 2020 · PPPoE connections might require special MTU settings to function properly. Providers tell their customers if their network requires a specific MTU value—numbers like 1492 (the maximum PPPoE supports) or 1480 are common. Home routers support an option to set the MTU size manually when needed. PPPoE MTU defines the maximum number of bytes that a PPPoE payload can have. This typically starts from IP layer in most cases. Below is what a typical PPPoE packet look like in terms of headers. Ethernet, then PPPoE then PPP followed by IP or IPv6 payload.