11-05-2018 01:03 PM - edited 11-05-2018 01:14 PM
hello
what would be the equivalent to this ip tcp adjust-mss 1360 ??? i cannot put in this command and the closest to it are these options
SLC_SW_3850_Stack(config-if)#ip tcp ?
compression-connections Maximum number of compressed connections
header-compression Enable TCP header compression
11-06-2018 12:52 AM
Hello,
I assume this is a tunnel interface you are trying to configure ? I don't think that command is available on the 3850...
11-26-2018 08:43 AM
Hi Can you share the show version?
BR
Gaston
11-27-2018 07:15 AM
11-27-2018 03:18 PM
I read something recently that indicates that 3850 has added support for GRE tunnels. I can not confirm whether that is accurate, but believe that it well may be.
The original post asks about equivalent commands. As far as I know there is not really an equivalent command. The neat thing about adjust-mss is that the router has an opportunity during the negotiation between the remote end points to affect their choice of mss. And this eliminates issues with fragmentation. Probably the closest to an equivalent is ip mtu applied to the tunnel interface. This would help if devices did Path MTU Discovery. But it still leaves open the possibility that the end points will send packets that are large enough to require fragmentation.
HTH
Rick
11-29-2018 06:16 AM
11-29-2018 06:48 AM
Joseph makes a good point about needing to configure adjust-mss on interfaces at both ends of the tunnel while adjust-mss only needs to be configured on a single side. The difference reflects the fact that adjust-mss affects the negotiation between end points of the tcp session and means that neither side will send a tcp packet that requires fragmentation. But setting mtu affects individual packets as they enter the tunnel and so needs to be implemented on both ends of the tunnel.
HTH
Rick
11-29-2018 07:32 AM
". . . makes a good point about needing to configure adjust-mss on interfaces at both ends of the tunnel while adjust-mss only needs to be configured on a single side. "
Rick, I beleive you meant to write: ". . . makes a good point about needing to configure IP MTU on interfaces at both ends of the tunnel while adjust-mss only needs to be configured on a single side. "
Also, as Rick notes, the IP TCP MSS-ADJUST needs to "see" the TCP startup, so it doesn't work on existing flows that switch into a path that has this command. (This is worth understanding, especially in situations where the tunnel is a backup path, that might accept existing flows that "fail-over" to it.)
11-29-2018 10:38 AM
Joseph
Thank you for spotting my mis-statement. Indeed I did intend to say IP mtu but somehow typed adjust-mss.
HTH
Rick
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