• Tag : MTU


Configurable MTU values for fwd interfaces

Description This feature provides the ability to configure the MTU value of fwd devices in a specific vrf or across vrfs. A default value of 1300 bytes is used in the absence of any configuration. This helps in accommodating additional headers that are added onto the packets by the hardware keeping the final packet size within the MTU of the egress interface thereby preventing packets from getting fragmented or dropped. Configuration The following CLI is available under “router-general” configuration mode and its vrf sub-mode. software forwarding hardware offload mtu <val> Global configuration under “router general” mode configures the fwd device...
Continue reading →

MRU Enforcement

Description MRU (maximum receive unit) enforcement provides the ability to drop frames that exceed a configured threshold on the ingress interface. Platform compatibility DCS-7020 DCS-7280R DCS-7280R2 DCS-7280R3 (Starting in 4.25.1F) DCS-7500R DCS-7500R2 DCS-7500R3 (Starting in 4.25.1F) Change Log 4.25.0F – initial release Support for MRU enforcement on Ethernet, Port-Channel and Sub-interfaces. 4.25.1F Support MRU enforcement on 7280R3 and 7500R3 platforms Support for per-chip MRU drop counter Configuration MRU is configurable per-interface, and can be configured on Ethernet and Port-Channel interfaces. Frames with size greater than the configured MRU value will be dropped on the ingress, and will not be forwarded...
Continue reading →

Global knob to set MTU for all layer 3 interfaces

Description Global layer 3 Maximum Transfer Unit (MTU) feature provides a CLI command to set the MTU value for all layer 3 interfaces. The default value for global layer 3 MTU and for each interface layer 3 MTU is 1500, which is unchanged from previous releases. Any interface which has an MTU configured will not be affected by the global L3 MTU. If the global L3 MTU is changed, any existing interfaces which are using the default will be updated to use the new MTU.  Any additional interfaces which are configured in the future will also use the new default...
Continue reading →

Support for L3 MTU on 7280R3/7500R3/7800R3

Add support for Layer 3 MTU on 7280R3/7500R3/7800R3 switches. Description Enforces the MTU for Layer 3 packets on 7280R3/7500R3/7800R3 switches. The MTU can be set on any SVI and the MTU of that specific SVI is enforced when the packets egress out of a trunk port.  This behavior is not supported on 7280E/R/R2 and 7500E/R/R2 line cards. MTU enforcement is done after adding all of the encapsulation headers in the Egress packet. For example, if an interface is configured with an MTU value of 1500 and the packet size is larger than 1500 with all encapsulation headers added, the packet...
Continue reading →

MPLS Tunnel Support for Traceroute and PMTU Discovery

Description IP traceroute and path MTU (PMTU) discovery both require that routers send ICMP reply messages to the host that invokes each network function.  When the route to the destination host traverses an MPLS label-switched path (LSP), the label switching routers (LSRs) will also need to send ICMP reply messages to the originating host. The MPLS ICMP tunneling feature enables these LSRs to generate ICMP reply messages and deliver them to the originating host using the same LSP on which the frame was received.  Once the frame exits the LSP, it is assumed that the ICMP reply can be routed...
Continue reading →

ISIS between Arista and IOS-XR

Hi I’m trying to establish isis between a cisco router, IOS-XR and 7280CR running 4.20.5F adjacency won’t come up. MTU on cisco side is 9216. on Arista side, IP MTU is configured as 9202. Layer2 MTU cannot be configured on this platform. hello-padding is disabled on both ends. I have 7280SR running an earlier version that works with the same cisco with the same configs. Has anyone had such problems with isis in 4.20.5F?

vEOS on ESXi – Jumbo MTU Problem

Hi, I run couples of latest vEOS switches on ESXi, trying to build a VXLAN lab to test. Between vEOS switches, I used standard virtual switch as a virtual cable for each individual connection.  In vSwitch settings, I’ve set the MTU to 9000. MTU1500 works OK. But ping test over 1500 bytes all failed. PING ( 1473(1501) bytes of data. ping: sendmsg: Network is unreachable ping: sendmsg: Network is unreachable ping: sendmsg: Network is unreachable Searching over Internet came up no result…. Any thought?  

Jumbo frame MTU sizes

Hi, How is the Jumbo frame MTU calculated in Arista vs. Cisco vs. Juniper? Max MTU in Arista -> 9214 vs. Cisco -> 9216 vs. Juniper -> 9192 They should all be the same frame size on the wire, right? (it’s a bit confusing that they are displayed differently in their respective OS…) Ex. EOS> show interfaces ethernet 1 | grep MTU IP MTU 9214 bytes , BW 10000000 kbit EOS> show interfaces ethernet 1 l2 mtu Port        MTU Config MTU Status ———-  ———- ———- Et1                          9234   JUNOS> show...
Continue reading →


Get every new post on this blog delivered to your Inbox.

Join other followers: