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Packet Captures

4-byte_AS_numbers_Mixed_Scenario.cap 414 bytes

Submitted Apr 30, 2010 by pierky

Router "B" (AS 2) at 172.16.3.2 does not support 4-byte AS numbers, while router "A" (AS 10.1 / 655361) at 172.16.3.1 does.

Router "A" receives an UPDATE for the 40.0.0.0/8 subnet from an external router ("D") in the AS 40.1 / 2621441 (not shown), and it forwards it to "B" (pkt n. 2): AS_PATH contains "23456 23456" (the first stands for AS 10.1, the second for the originating AS 40.1), but NEW_AS_PATH contains the real 4-byte AS numbers.

At pkt n. 3 "B" receives the same subnet directly from "D" and sends it to "A", including the original NEW_AS_PATH attribute previously appended by "D".

BGP HDLC IP TCP

Packets: 4 Duration: 60s Downloads: 6800

4-byte_AS_numbers_Full_Support.cap 1.2 KB

Submitted Apr 30, 2010 by pierky

Router at 172.16.1.2 (hostname "D", AS 40.1 / 2621441) clears a previous established peering with 172.16.1.1 (hostname "A", AS 10.1 / 655361); They both support 32-bit ASN.

While opening the new session, they negotiate the "Four-octet AS Number Capability" (pkts n. 2 and 3).

Then, both "A" and "D" send some UPDATEs containing 4-octect encoded AS_PATH attributes (pkts n. 6 and 9). Please note: WireShark may show wrong paths unless you force 4-byte encoding in the Preferences / Protocols / BGP options.

BGP HDLC IP TCP

Packets: 9 Duration: 56s Downloads: 6265

BGP_redist.cap 378 bytes

Submitted Oct 28, 2009 by colinbsd

The OSPF metric is preserved and propagated within the MPLS cloud by the MP-BGP MED attribute.

BGP HDLC IP MPLS TCP

Packets: 2 Duration: n/a Downloads: 7218

OSPF_Down-Bit.cap 8.9 KB

Submitted Oct 27, 2009 by colinbsd

LSA Update with down bit set. Router R5 56.0.0.5 PE is receiving an update from the MPLS VPN, which is advertised to CE 56.0.0.6 ospf routing table. In order for for the packet(LSA) not to be re-advertised back into the MPLS cloud through another PE(2) router, PE sets the Down-bit to 1. filter: ospf.v2.options.dn == 1

CDP HDLC IP OSPF SLARP

Packets: 98 Duration: 203s Downloads: 6495

ISIS_p2p_adjacency.cap 21.7 KB

Submitted Sep 14, 2009

Routers 1 and 2 form a L1/L2 adjacency over a point-to-point serial link. Note that both levels of adjacency are managed with a point-to-point (P2P) hello.

HDLC ISIS

Packets: 26 Duration: 113s Downloads: 5694

HDLC.cap 3.4 KB

Submitted Sep 14, 2009

ICMP across an HDLC serial link.

CDP HDLC ICMP IP SLARP

Packets: 38 Duration: 111s Downloads: 4339