IPv6 contact for www.citrix.com - MTU problem?

[Brandon Applegate]

>From what I can tell, the MSS is 1360 and I never get a packet bigger than 
this from www.citrix.com.  This is a pcap that was filtered to their ipv6 
address only (capture filter was 'host 2001:1890:111e:201::15' even 
though I am just looking at 'src' below), and I typed the URL into my 
browser, waited for the page to load, and stopped the tcpdump.  I should 
also mention that I am doing the tcpdump on my 'tunnel endpoint' - that is 
to say the linux box in the DC at the other end of my tunnel.  This is 
where PMTUD would kick in and I wanted to see it in action there if 
applicable.

root at phosphor:/home/bapplegate# tcpdump -r www.citrix.com.pcap src 
2001:1890:111e:201::15 | awk '{print $15}' | sort -n | uniq | tail -1
reading from file www.citrix.com.pcap, link-type EN10MB (Ethernet)
1360

The dns hostnames seem to indicate they are doing GSLB (I assume 
netscaler, dog food, etc).  Perhaps you are getting a different answer 
from where you are and there is indeed an MTU problem on whatever instance 
you are talking to.

Even though I can't recreate it, hopefully some of this information helps. 
I'm curious to see what else you find out.

--
Brandon Applegate - CCIE 10273
PGP Key fingerprint:
7407 DC86 AA7B A57F 62D1 A715 3C63 66A1 181E 6996
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