01-27-2017 07:18 PM - edited 03-08-2019 09:05 AM
We recently deployed a 2960X switch in IP routing mode. We have a couple SVIs. We are able to configure "ip tcp adjust-mss 1300" on the SVI but it doesn't appear to to work. Wireshark on the PC and server show the TCP ack and syn-ack both have ~1467. I expect the adjust-mss command to re-write the TCP parameters to spoof the connecting into negotiating down to 1300, but it isn't happening.
I can't find ip tcp adjust-mss xxxx in the 2960X documentation so I'm wondering if it's a bogus command.
Should the "ip tcp adjust-mss xxxx" command work on the 2960X?
Thank you
01-28-2017 12:28 AM
Hello,
which template are you using ? What is the output of 'show sdm prefer' ?
01-29-2017 05:50 PM
I'll be able to run the command monday at work. But we are doing it all via cli directly. No SDM.
01-30-2017 12:45 AM
I think Georg means in cli , your SDM should be set to routing as your trying to use a layer 3 command on a what can be set just as a layer 2 switch
xxxxxxxxxxx#sh sdm ?
prefer Show current template configuration
xxxxxxxxxxx#sh sdm prefer
The current template is "default" template.
The selected template optimizes the resources in
the switch to support this level of features for
0 routed interfaces and 255 VLANs.
number of unicast mac addresses: 8K
number of IPv4 IGMP groups: 0.25K
number of IPv6 multicast groups: 0.25K
number of IPv4/MAC qos aces: 0.375k
number of IPv4/MAC security aces: 0.375k
number of IPv6 policy based routing aces: 0
number of IPv6 qos aces: 0
number of IPv6 security aces: 0.125k
Setting the SDM Template
Beginning in privileged EXEC mode, follow these steps to use the SDM template to maximize feature
usage:
After the system reboots, you can use the show sdm prefer privileged EXEC command to verify the new
template configuration. If you enter the show sdm prefer command before you enter the reload
privileged EXEC command, the show sdm prefer command shows the template in use and the template that
becomes active after a reload.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 sdm prefer {default | dual-ipv4-and-ipv6
default | lanbase-routing | qos}
Specify the SDM template to be used on the switch:
The keywords have these meanings:
dual stack environments (supporting both IPv4 and IPv6).
routing on SVIs.
Use the no sdm prefer command to set the switch to the default
template. The default template balances the use of system resources.
Note The Catalyst 2960-S switch supports only the default and
lanbase-routing templates.
Step 3 end Return to privileged EXEC mode.
Step 4 reload Reload the operating system.
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