[c-nsp] TCP MSS on IOS XR

[Jared Mauch]

What version of IOS-XR?  What are the interface MTUs?

There were a number of TCP enhancements that went in around the 5.1 timeframe which impact the way window scaling works as well.

Also, do you have path-mtu enabled on all the devices?

on XR you want something like this:

tcp selective-ack
tcp window-size 65535
tcp path-mtu-discovery

IOS:

ip tcp path-mtu-discovery
ip tcp window-size 65535

- Jared

> On Apr 28, 2015, at 12:46 PM, Jordi Magrané Roig <jordimagrane at hotmail.com> wrote:
> 
> Dear colleagues,
> 
> I have an ASR9000 and I have a BGP session with an IOS device. The output of the command "show tcp detail pcb" shows the following information:
> 
> output omitted
> 
> 
> Datagrams (in bytes): MSS 1460, peer MSS 1460, min MSS 1946, max MSS
> 1946
> 
> output omitted
> 
> The IOS device is using MSS 1460 bytes but I don't know exactly the MSS that the IOS XR device is using, 1460 or 1946.
> 
> Do you know how the command must be interpreted?
> 
> Thanks,
> Jordi.
> 
> 
> 		 	   		  
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