Hi Oli, thanks for your inputs, will add this to my test document. Best Regards for the NSP's help.
2012/8/1 Oliver Boehmer (oboehmer) <[email protected]> > well, you don't have to use TCP, but it's the most convinient as you > have the client prepared to react to the packet-too-big ICMP/ICMPv6 > messages from intermediate nodes, and see the effect it has on the MSS. You > can't test this just by sending icmp packets from the CLI?! **** > > And to your question: yes, it is the MSS reported, and the below output > suggests that you have PMTUD enabled on the routers and you're using a min > MTU of 1500 along the path, otherwise the nodes would have used MSS=532 or > something low like this..**** > > ** ** > > oli**** > > ** ** > > *From:* Xu Hu [mailto:[email protected]] > *Sent:* 01 August 2012 15:54 > > *To:* Oliver Boehmer (oboehmer) > *Cc:* [email protected] > *Subject:* Re: [c-nsp] Fwd: IPV6 Path MTU DIscovery Test**** > > ** ** > > Must use the TCP packets? I want to just use the ping packet to test the > effect of PMTUD. Is any simple way to test this feature?**** > > ** ** > > Another thing, if use the iBGP to test, i find one show ip bgp neighbor > command as below, the MSS you mentioned is the "*Datagrams (max data > segment is 1460 bytes):*" ?**** > > ** ** > > Thanks for your help.**** > > Hu Xu**** > > ** ** > > Router# *show ip bgp neighbors 172.16.232.178* > > > > **** > > BGP neighbor is 172.16.232.178, remote AS 10, external link**** > > Index 1, Offset 0, Mask 0x2**** > > Inbound soft reconfiguration allowed**** > > BGP version 4, remote router ID 172.16.232.178**** > > BGP state = Established, table version = 27, up for 00:06:12**** > > Last read 00:00:12, hold time is 180, keepalive interval is 60 seconds**** > > Minimum time between advertisement runs is 30 seconds**** > > Received 19 messages, 0 notifications, 0 in queue**** > > Sent 17 messages, 0 notifications, 0 in queue**** > > Inbound path policy configured**** > > Route map for incoming advertisements is testing**** > > Connections established 2; dropped 1**** > > Connection state is ESTAB, I/O status: 1, unread input bytes: 0**** > > Local host: 172.16.232.181, Local port: 11002**** > > Foreign host: 172.16.232.178, Foreign port: 179**** > > > > **** > > Enqueued packets for retransmit: 0, input: 0, saved: 0**** > > > > **** > > Event Timers (current time is 0x530C294):**** > > Timer Starts Wakeups Next**** > > Retrans 12 0 0x0**** > > TimeWait 0 0 0x0**** > > AckHold 12 10 0x0**** > > SendWnd 0 0 0x0**** > > KeepAlive 0 0 0x0**** > > GiveUp 0 0 0x0**** > > PmtuAger 0 0 0x0**** > > > > **** > > iss: 133981889 snduna: 133982166 sndnxt: 133982166 sndwnd: > 16108**** > > irs: 3317025518 rcvnxt: 3317025810 rcvwnd: 16093 delrcvwnd: 291**** > > > > **** > > SRTT: 441 ms, RTTO: 2784 ms, RTV: 951 ms, KRTT: 0 ms**** > > minRTT: 0 ms, maxRTT: 300 ms, ACK hold: 300 ms**** > > Flags: higher precedence, nagle**** > > > > **** > > *Datagrams (max data segment is 1460 bytes):***** > > Rcvd: 15 (out of order: 0), with data: 12, total data bytes: 291**** > > Sent: 23 (retransmit: 0), with data: 11, total data bytes: 276**** > > ** ** > > 2012/8/1 Oliver Boehmer (oboehmer) <[email protected]>**** > > Well, you need to create TCP connections to see the effect of PMTUD.. you > could build an iBGP session across the test network, and play around with > the minimum link MTU along the path. The MSS (shown in show bgp neighbor > ..) should adapt as you change it.. > > oli**** > > > > -----Original Message----- > > From: [email protected] [mailto:cisco-nsp- > > [email protected]] On Behalf Of Xu Hu > > Sent: 01 August 2012 02:33 > > To: [email protected] > > Subject: [c-nsp] Fwd: IPV6 Path MTU DIscovery Test > > > > Anybody have any good idea? > > > > Thanks advance for any inputs, > > Xu Hu > > > > Begin forwarded message: > > > > > From: TJ <[email protected]> > > > Date: 1 August, 2012 5:23:46 GMT+08:00 > > > To: Xu Hu <[email protected]> > > > Subject: Re: [c-nsp] IPV6 Path MTU DIscovery Test > > > Reply-To: [email protected] > > > > > > In order to test it, take one of the links along the path and change > the > > (IPv6) MTU to something smaller - say 1300B. Then send large packets, > with > > WireShark running. And no, you cannot disable PMTUD in IPv6. > > > > > > HTH! > > > /TJ > > > > > > > > > On Tue, Jul 31, 2012 at 6:43 AM, Xu Hu <[email protected]> wrote: > > > Hi Experts, > > > > > > I have some queries about the PMTU for IPv6. > > > 1. From my understanding, path MTU discovery in IPv6 allows a host to > > > dynamically discover and adjust to differences in the MTU size of every > > > link along a given data path, So the fragmentation is handled by the > > > source, if i want to test this feature in the IPv6 network, anyone have > > any > > > good ideas? > > > For example, as below topology, if i want to test the Path MTU > discovery, > > > how to test, i can ping from CE-1 to CE--2 with a specific IPv6 packet > > > size. > > > CE-1------PE-1------------PE-2--------CE-2 > > > > > > 2. If i need to configure the Path MTU discovery, just one command > > > mentioned in Cisco.com, which is "ipv6 flowset" under configuration > mode. > > > So if i want to disable that in test scenario, just using the "no ipv6 > > > flowset" is okay? Cisco don't mentioned that. > > > By default, it is enable for ip routers or not? > > > > > > Thanks for any inputs. > > > > > > Best Regards, > > > Hu Xu > > > _______________________________________________ > > > cisco-nsp mailing list [email protected] > > > https://puck.nether.net/mailman/listinfo/cisco-nsp > > > archive at http://puck.nether.net/pipermail/cisco-nsp/ > > > > > _______________________________________________ > > cisco-nsp mailing list [email protected] > > https://puck.nether.net/mailman/listinfo/cisco-nsp > > archive at http://puck.nether.net/pipermail/cisco-nsp/**** > > ** ** > _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
