The MPLS-OPS Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] Re: Unidentified subject!
long one indeed but a good q though. case-1 is expected. A good workaround for your situation wd be. 1. Do not 'autoroute-announce' on P1. Instead use a static route, ip route <PE2> /32 tunn100 that shd do the trick. PLs let me know if you have any q's rgds, gopal --- "M. ELK" <elkou141061@hotmail.com> wrote: <HR> <html><div style='background-color:'><DIV><FONT face="Courier New" color=#000000 size=1> <P><FONT face="Courier New, Courier, Monospace">Consider the following topo :</FONT></P> <P><FONT face="Courier New, Courier, Monospace">PE1---P1----P2----P3---PE2 </FONT></P> <P> |----PE3</P> <P> </P> <P><FONT face="Courier New, Courier, Monospace"></FONT></P> <P><FONT face="Courier New, Courier, Monospace">In word (in case the drawing is wrongly displayed)</FONT></P> <P><FONT face="Courier New, Courier, Monospace">PE1 to P1 , P1 to P2, P2 to P3 ,PE2 to P3 ,PE3 to P3 . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">All nodes run LDP :</FONT></P> <P><FONT face="Courier New, Courier, Monospace">LDP session P2-P3 :</FONT></P> <P><FONT face="Courier New, Courier, Monospace">P3 advertise L32 for PE2 /32 prefix </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P3 advertise L33 for PE3 /32 prefix </FONT></P> <P><FONT face="Courier New, Courier, Monospace">LDP session P2-P1 :</FONT></P> <P><FONT face="Courier New, Courier, Monospace">P2 advertise L22 for PE2 /32 prefix </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P2 advertise L23 for PE3 /32 prefix </FONT></P> <P><FONT face="Courier New, Courier, Monospace"></FONT></P> <P><FONT face="Courier New, Courier, Monospace">LDP session P1-PE1 :</FONT></P> <P><FONT face="Courier New, Courier, Monospace">P1 advertise L12 for PE2 /32 prefix </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P1 advertise L13 for PE3 /32 prefix </FONT></P> <P><FONT face="Courier New, Courier, Monospace">we configure a RSVP-TE tunnel (Tunel100 ) from P1 to P3 , </FONT></P> <P><FONT face="Courier New, Courier, Monospace">as a result of the signalling P3 advertise "implicit null"</FONT></P> <P><FONT face="Courier New, Courier, Monospace">to P2 , P2 advertise L2t to P1 . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">AT P1 under tunnel100 we config autoroute-announce . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">tunnel100 is considered the next-hop to P3 and any </FONT></P> <P><FONT face="Courier New, Courier, Monospace">downstream nodes (PE2 and PE3) </FONT></P> <P><FONT face="Courier New, Courier, Monospace"></FONT></P> <P><FONT face="Courier New, Courier, Monospace">We initiate directed LDP session between P1 and P3 , we control P3 </FONT></P> <P><FONT face="Courier New, Courier, Monospace">config such that P3 will only advertise label for PE2 over this </FONT></P> <P><FONT face="Courier New, Courier, Monospace">directed LDP session . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">LDP session P1-P3 :</FONT></P> <P><FONT face="Courier New, Courier, Monospace">P3 advertise L3d for prefix PE2 /32 (L3d could be same value </FONT></P> <P><FONT face="Courier New, Courier, Monospace">as L32 ) .</FONT></P> <P><FONT face="Courier New, Courier, Monospace">For traffic from VPn1 connected on PE1 to VPN2 connected to PE2 : </FONT></P> <P><FONT face="Courier New, Courier, Monospace">PE1 will send labeled backet with depth 2 </FONT></P> <P><FONT face="Courier New, Courier, Monospace">(Top Label = L12 ,bottom Label= L2vpn . L2vpn recieved through</FONT></P> <P><FONT face="Courier New, Courier, Monospace">Mp-iBGP PE1/PE2 ) </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P1 will swap L12 with L3d and forward the traffic over the tunnel.</FONT></P> <P><FONT face="Courier New, Courier, Monospace">The label packet forwarded to P2 now have 3 label </FONT></P> <P><FONT face="Courier New, Courier, Monospace">(Top Label = L2t ,2nd label=L3d ,last label=Lv2pn) </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P2 will pop the top label and forwarded the label packet to P3 </FONT></P> <P><FONT face="Courier New, Courier, Monospace">with just </FONT><FONT face="Courier New, Courier, Monospace">2 label (Top label=L3d ,last label=Lv2pn ) .</FONT></P> <P><FONT face="Courier New, Courier, Monospace">P3 will pop the top label (L3d) and forward the packet with top </FONT></P> <P><FONT face="Courier New, Courier, Monospace">label Lv2Pn to PE2. </FONT></P> <P><FONT face="Courier New, Courier, Monospace">From the above it is working fine . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">For traffic from VPn1 connected on PE1 to VPN3 connected to PE3 : </FONT></P> <P><FONT face="Courier New, Courier, Monospace">PE1 will send labeled backet with depth 2 </FONT></P> <P><FONT face="Courier New, Courier, Monospace">(Top Label = L13 ,bottom Label= L3vpn . L3vpn recieved through</FONT></P> <P><FONT face="Courier New, Courier, Monospace">Mp-iBGP PE1/PE3 ) </FONT></P> <P><FONT face="Courier New, Courier, Monospace">What P1 will do :</FONT></P> <P><FONT face="Courier New, Courier, Monospace">Case1 : P1 will notice that L13 is associated with action "untag" </FONT></P> <P><FONT face="Courier New, Courier, Monospace">but L13 is not the bottom of stack so it drop the packet .</FONT></P> <P><FONT face="Courier New, Courier, Monospace">Or </FONT></P> <P><FONT face="Courier New, Courier, Monospace">Case2 : P1 next-hop to P3 and downstream nodes (PE1 and PE2) </FONT></P> <P><FONT face="Courier New, Courier, Monospace">is through tunnel100 . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P1 pop L13 and push L2t and forward to P2 ,now the </FONT></P> <P><FONT face="Courier New, Courier, Monospace">label packet with stack of depth 2 (top= L2t ,bottom=L3vpn)</FONT></P> <P><FONT face="Courier New, Courier, Monospace">P2 pop the top label and forward to P3 . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P3 will recieve a labeled packet with depth 1 and label=L3vpn.</FONT></P> <P><FONT face="Courier New, Courier, Monospace">P3 will drop the packet as l3vpn is unknown . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">Or </FONT></P> <P><FONT face="Courier New, Courier, Monospace">case3 : P1 will notice that despite tunnel100 is the next-hop to </FONT></P> <P><FONT face="Courier New, Courier, Monospace">PE3 still P1 did not recieved a label for PE3 from P3 . so </FONT></P> <P><FONT face="Courier New, Courier, Monospace">recieved packet with top label=L13 but the stack depth is > 1 can not</FONT></P> <P><FONT face="Courier New, Courier, Monospace">be forwarded over tunnel100 and it need to be forwarded over other </FONT></P> <P><FONT face="Courier New, Courier, Monospace">interface where a label for PE3 is recieved . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P1 will swap L13 with L22 ( Top label=L22, bottom label=L3vpn)</FONT></P> <P><FONT face="Courier New, Courier, Monospace">and forward to P2 . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P2 swap L22 with L32 and forward to P3 . </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P3 pop L32 and forward the label packet (with single label=L3vpn) </FONT></P> <P><FONT face="Courier New, Courier, Monospace">to PE3 . </FONT></P> <P><FONT face="Courier New, Courier, Monospace"></FONT> </P> <P><FONT face="Courier New, Courier, Monospace">So what is the expected behaviour of P1 ? </FONT></P> <P><FONT face="Courier New, Courier, Monospace"></FONT> </P> <P><FONT face="Courier New, Courier, Monospace">From the above it is clear that i want to control which traffic from </FONT></P> <P><FONT face="Courier New, Courier, Monospace">P1 </FONT><FONT face="Courier New, Courier, Monospace">(to downstrean nodes of P3 ) will use the tunnel by controlling </FONT></P> <P><FONT face="Courier New, Courier, Monospace">what label(s) </FONT><FONT face="Courier New, Courier, Monospace">the tail-end (P3) will advertise through the LDP session</FONT></P> <P><FONT face="Courier New, Courier, Monospace">to the head-end (P1) ,</FONT><FONT face="Courier New, Courier, Monospace">if their is other method to achieve the same pls</FONT></P> <P><FONT face="Courier New, Courier, Monospace"> advise .</FONT></P> <P><FONT face="Courier New, Courier, Monospace">Specific to which box is in use , it is cisco box but just glancing on</FONT></P> <P><FONT face="Courier New, Courier, Monospace">JNP </FONT><FONT face="Courier New, Courier, Monospace">documentation it seems (not sure) that their is way to achieve </FONT></P> <P><FONT face="Courier New, Courier, Monospace">this with JNP . </FONT><FONT face="Courier New, Courier, Monospace">JNP allow to assign distance to route learned through </FONT></P> <P><FONT face="Courier New, Courier, Monospace">LDP to be higher than route </FONT><FONT face="Courier New, Courier, Monospace">learned through IGP </FONT></P> <P><FONT face="Courier New, Courier, Monospace">(In other word , if labelled route is recieved for prefix is </FONT></P> <P><FONT face="Courier New, Courier, Monospace">cosnidered first before any un-labelled route ) .so if we ping from P1 </FONT></P> <P><FONT face="Courier New, Courier, Monospace">to PE3 ,P1 will generate a label packet </FONT><FONT face="Courier New, Courier, Monospace">with single label L23 in case </FONT></P> <P><FONT face="Courier New, Courier, Monospace">of JNP while i guess cisco will generate a label packet</FONT></P> <P><FONT face="Courier New, Courier, Monospace">with top label L3t .Could You Pls comment on this point .</FONT></P> <P>Brgds </P></FONT></DIV></div><br clear=all><hr>Help STOP SPAM with <a href="http://g.msn.com/8HMREN/2016">the new MSN 8 </a> and get 2 months FREE*</html> ------- The MPLS-OPS Mailing List Subscribe/Unsubscribe: http://www.mplsrc.com/mplsops.shtml Archive: http://www.mplsrc.com/mpls-ops_archive.shtml __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com ------- The MPLS-OPS Mailing List Subscribe/Unsubscribe: http://www.mplsrc.com/mplsops.shtml Archive: http://www.mplsrc.com/mpls-ops_archive.shtml
|
|