---------- Forwarded message ---------- From: "Brian Dennis" To: "Anthony Sequeira" , "Cisco certification" Date: Wed, 7 Dec 2005 01:14:32 -0500 Subject: RE: Verifying Route Tags This isn't pretty but here goes: R1 and R4 are connected via Ethernet (155.1.146.0/24) and R4 is redistributing OSPF into RIP. R4 is setting the tag for these routes to 4110. I used 4110 because its R4's OSPF routes (4 for R4 and 110 for OSPF's administrative distance) but any number would work. Rack1R4#sho run | be router rip router rip version 2 redistribute ospf 1 metric 5 route-map OSPF->RIP network 155.1.0.0 no auto-summary ! route-map OSPF->RIP permit 10 set tag 4110 We'll match the RIP updates from R4 on R1 with an ACL and use the hidden "dump" option on the debug ip packet command along with the ACL so that we can view the whole RIP packet. Rack1R1# Rack1R1#conf t Enter configuration commands, one per line. End with CNTL/Z. Rack1R1(config)#access-list 100 permit udp host 155.1.146.4 any eq rip Rack1R1(config)#^Z Rack1R1#deb ip pack 100 dump IP packet debugging is on (dump) for access list 100 Rack1R1# *Mar 1 10:45:50.661: IP: s=155.1.146.4 (FastEthernet0/0), d=224.0.0.9, len 372, rcvd 2 03C036C0: 0100 5E000009 ..^... 03C036D0: 0030947E E5820800 45C00174 00000000 .0.~e...E@.t.... 03C036E0: 0111AAAA 9B019204 E0000009 02080208 ..**....`....... 03C036F0: 0160A3B0 02020000 0002100E 96010000 .`#0............ 03C03700: FFFF0000 00000000 00000005 00020000 ................ 03C03710: 96010200 FFFFFF00 00000000 00000003 ................ 03C03720: 00020000 96010400 FFFFFF00 00000000 ................ 03C03730: 00000001 00020000 96010500 FFFFFF00 ................ 03C03740: 00000000 00000002 0002100E 96010808 ................ 03C03750: FFFFFFFF 00000000 00000005 00020000 ................ 03C03760: 9B010000 FFFFFF00 00000000 00000001 ................ 03C03770: 0002100E 9B010500 FFFFFF00 00000000 ................ 03C03780: 00000005 0002100E 9B010700 FFFFFF00 ................ 03C03790: 00000000 00000005 0002100E 9B010800 ................ Rack1R1# Let's take this line and break it down: 03C03770: 0002100E 9B010500 FFFFFF00 00000000 ................ 02 means its address family is IP. 100E is the tag in hex (4110 in decimal). 9B is 155. 01 is 1. 05 is 5 and finally 00 is 0. FFFFFF00 is 255.255.255.0 for the subnet mask of the route so this is network 155.1.5.0/24 with a tag of 4110. So okay there may be a better way but this way is really cool. Also remember that the calculator is your friend when looking at packet dumps ;-) HTH, Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security) bdennis@internetworkexpert.com Internetwork Expert, Inc. http://www.InternetworkExpert.com Toll Free: 877-224-8987 Direct: 775-745-6404 (Outside the US and Canada) ---